diff --git a/.changeset/report-cli-vscode-presence.md b/.changeset/report-cli-vscode-presence.md
new file mode 100644
index 0000000000..c5229c240f
--- /dev/null
+++ b/.changeset/report-cli-vscode-presence.md
@@ -0,0 +1,6 @@
+---
+"@kilocode/cli": minor
+"kilo-code": minor
+---
+
+Report active CLI and VS Code app and session presence.
diff --git a/packages/kilo-console/src/client.test.ts b/packages/kilo-console/src/client.test.ts
index 4c94e5e909..4a964733d8 100644
--- a/packages/kilo-console/src/client.test.ts
+++ b/packages/kilo-console/src/client.test.ts
@@ -1,17 +1,21 @@
 import { expect, test } from "bun:test"
 
-function setup() {
-  const calls: Array<{ url: string; method: string; body: unknown }> = []
-  const win = {
-    fetch: async (input: RequestInfo | URL, init?: RequestInit) => {
-      const req = input instanceof Request ? input : new Request(input, init)
-      calls.push({ url: req.url, method: req.method, body: await req.json() })
-      return new Response(JSON.stringify({ permission: { edit: { "*": "allow" } } }), {
-        headers: { "content-type": "application/json" },
-      })
-    },
-  }
+// client.ts binds window.fetch once at import time, so every test must share the
+// same window whose fetch writes into a swappable calls array.
+let calls: Array<{ url: string; method: string; body: unknown }> = []
 
+const win = {
+  fetch: async (input: RequestInfo | URL, init?: RequestInit) => {
+    const req = input instanceof Request ? input : new Request(input, init)
+    calls.push({ url: req.url, method: req.method, body: await req.json() })
+    return new Response(JSON.stringify({ permission: { edit: { "*": "allow" } } }), {
+      headers: { "content-type": "application/json" },
+    })
+  },
+}
+
+function setup() {
+  calls = []
   Object.defineProperty(globalThis, "window", { value: win, configurable: true })
   return calls
 }
@@ -46,3 +50,24 @@ test("config writes include the selected directory", async () => {
     unset: [["indexing", "model"]],
   })
 })
+
+test("viewed snapshots post the presence payload against the selected directory", async () => {
+  const calls = setup()
+  const client = await import("./client")
+  const query = { url: "http://kilo:secret@127.0.0.1:4097", dir: "/tmp/project" }
+  const viewer = { id: "11111111-1111-4111-8111-111111111111", active: false }
+
+  await client.viewProjectSessions(query, viewer, ["ses_selected", "ses_terminal"], [])
+
+  expect(calls).toHaveLength(1)
+
+  const viewed = calls[0]
+  expect(viewed.method).toBe("POST")
+  expect(new URL(viewed.url).pathname).toBe("/session/viewed")
+  expect(new URL(viewed.url).searchParams.get("directory")).toBe("/tmp/project")
+  expect(viewed.body).toEqual({
+    viewer: { id: "11111111-1111-4111-8111-111111111111", active: false },
+    attached: ["ses_selected", "ses_terminal"],
+    visible: [],
+  })
+})
diff --git a/packages/kilo-console/src/client.ts b/packages/kilo-console/src/client.ts
index b1e74cadc1..9a3781c10a 100644
--- a/packages/kilo-console/src/client.ts
+++ b/packages/kilo-console/src/client.ts
@@ -628,9 +628,14 @@ export async function removeProjectPty(input: Query, pty: string) {
   return demand("Remove terminal", result)
 }
 
-export async function viewProjectSessions(input: ProjectQuery, focused: string[], open: string[]) {
+export async function viewProjectSessions(
+  input: ProjectQuery,
+  viewer: { id: string; active: boolean },
+  attached: string[],
+  visible: string[],
+) {
   const sdk = client(input)
-  const result = await sdk.session.viewed({ directory: input.dir, focused, open })
+  const result = await sdk.session.viewed({ directory: input.dir, viewer, attached, visible })
   return demand("Viewed sessions", result)
 }
 
diff --git a/packages/kilo-console/src/routes/projects/ProjectConsoleRoute.tsx b/packages/kilo-console/src/routes/projects/ProjectConsoleRoute.tsx
index 5363f208db..f76a2db973 100644
--- a/packages/kilo-console/src/routes/projects/ProjectConsoleRoute.tsx
+++ b/packages/kilo-console/src/routes/projects/ProjectConsoleRoute.tsx
@@ -49,6 +49,7 @@ import {
   normalizeConsoleDiffStyle,
   normalizeContextSidebarWidth,
 } from "../config/state/console"
+import { sender } from "./project-console-presence-sender"
 import { GhosttyTerminal } from "./terminal/GhosttyTerminal"
 
 const ui = new Set(["3017", "3018"])
@@ -147,6 +148,7 @@ function terminalKey(url: string, item: ProjectTerminalItem) {
 export function ProjectConsoleRoute() {
   const loc = useLocation()
   const params = useParams()
+  const viewerId = crypto.randomUUID()
   const search = createMemo(() => new URLSearchParams(loc.search))
   const fallback = () => base(search())
   const [url, setUrl] = createSignal(fallback())
@@ -660,19 +662,37 @@ export function ProjectConsoleRoute() {
     if (item) clearUnread(item)
   })
 
-  createEffect(() => {
+  let lastInput: { url: string; dir: string } | undefined
+  const queue = sender((err) => console.warn(`Viewed sessions: ${errMsg(err)}`))
+
+  function sendSnapshot(force = false) {
     const base = query()
     const data = snap()
     if (!base || !data) return
-    const focused = activeSessionID()
-    const open = terminals().flatMap((item) => {
+    const selected = activeSessionID()
+    const ids = new Set<string>()
+    if (selected) ids.add(selected)
+    for (const item of terminals()) {
       const id = sessionID(item)
-      return id ? [id] : []
-    })
-    void viewProjectSessions({ url: base.url, dir: data.project.worktree }, focused ? [focused] : [], open).catch(
-      () => {},
+      if (id) ids.add(id)
+    }
+    const input = { url: base.url, dir: data.project.worktree }
+    const key = input.url + "|" + input.dir + "|" + [...ids].sort().join(",")
+    lastInput = input
+    queue.push(
+      {
+        key,
+        run: async () => {
+          await viewProjectSessions(input, { id: viewerId, active: false }, [...ids], [])
+        },
+      },
+      force,
     )
-  })
+  }
+
+  createEffect(() => sendSnapshot())
+
+  const checkin = window.setInterval(() => sendSnapshot(true), 60_000)
 
   createEffect(() => {
     const base = query()
@@ -704,6 +724,19 @@ export function ProjectConsoleRoute() {
   onCleanup(() => {
     if (events.timer) window.clearTimeout(events.timer)
     if (resize.timer) window.clearTimeout(resize.timer)
+    window.clearInterval(checkin)
+    if (lastInput) {
+      const input = lastInput
+      queue.push(
+        {
+          key: input.url + "|" + input.dir + "|",
+          run: async () => {
+            await viewProjectSessions(input, { id: viewerId, active: false }, [], [])
+          },
+        },
+        true,
+      )
+    }
   })
 
   createEffect(() => {
diff --git a/packages/kilo-console/src/routes/projects/project-console-presence-sender.test.ts b/packages/kilo-console/src/routes/projects/project-console-presence-sender.test.ts
new file mode 100644
index 0000000000..c0fe5f855b
--- /dev/null
+++ b/packages/kilo-console/src/routes/projects/project-console-presence-sender.test.ts
@@ -0,0 +1,90 @@
+import { describe, expect, test } from "bun:test"
+import { sender } from "./project-console-presence-sender"
+
+function deferred() {
+  const state: { resolve?: () => void } = {}
+  const promise = new Promise<void>((resolve) => {
+    state.resolve = resolve
+  })
+  return { promise, resolve: () => state.resolve?.() }
+}
+
+async function drain() {
+  await Promise.resolve()
+  await Promise.resolve()
+}
+
+describe("project console presence sender", () => {
+  test("sends snapshots in order", async () => {
+    const first = deferred()
+    const calls: string[] = []
+    const queue = sender(() => {})
+
+    queue.push({ key: "first", run: () => (calls.push("first"), first.promise) })
+    queue.push({ key: "second", run: async () => void calls.push("second") })
+
+    expect(calls).toEqual(["first"])
+    first.resolve()
+    await drain()
+    expect(calls).toEqual(["first", "second"])
+  })
+
+  test("deduplicates the last successful snapshot unless forced", async () => {
+    const calls: string[] = []
+    const queue = sender(() => {})
+    const item = { key: "same", run: async () => void calls.push("same") }
+
+    queue.push(item)
+    await drain()
+    queue.push(item)
+    await drain()
+    expect(calls).toEqual(["same"])
+
+    queue.push(item, true)
+    await drain()
+    expect(calls).toEqual(["same", "same"])
+  })
+
+  test("does not queue a reactive duplicate of an in-flight snapshot", async () => {
+    const wait = deferred()
+    const calls: string[] = []
+    const queue = sender(() => {})
+    const item = { key: "same", run: () => (calls.push("same"), wait.promise) }
+
+    queue.push(item)
+    queue.push(item)
+    wait.resolve()
+    await drain()
+
+    expect(calls).toEqual(["same"])
+  })
+
+  test("retains a forced renewal while the same snapshot is in flight", async () => {
+    const wait = deferred()
+    const calls: string[] = []
+    const queue = sender(() => {})
+    const item = { key: "same", run: () => (calls.push("same"), calls.length === 1 ? wait.promise : Promise.resolve()) }
+
+    queue.push(item)
+    queue.push(item, true)
+    expect(calls).toEqual(["same"])
+
+    wait.resolve()
+    await drain()
+    expect(calls).toEqual(["same", "same"])
+  })
+
+  test("replaces an obsolete pending snapshot with the latest state", async () => {
+    const first = deferred()
+    const calls: string[] = []
+    const queue = sender(() => {})
+
+    queue.push({ key: "first", run: () => (calls.push("first"), first.promise) })
+    queue.push({ key: "second", run: async () => void calls.push("second") })
+    queue.push({ key: "third", run: async () => void calls.push("third") })
+
+    first.resolve()
+    await drain()
+    expect(calls).toEqual(["first", "third"])
+  })
+})
diff --git a/packages/kilo-console/src/routes/projects/project-console-presence-sender.ts b/packages/kilo-console/src/routes/projects/project-console-presence-sender.ts
new file mode 100644
index 0000000000..e2363a4dbe
--- /dev/null
+++ b/packages/kilo-console/src/routes/projects/project-console-presence-sender.ts
@@ -0,0 +1,34 @@
+type Snapshot = {
+  key: string
+  run: () => Promise<void>
+}
+
+export function sender(report: (err: unknown) => void) {
+  let current: Snapshot | undefined
+  let next: Snapshot | undefined
+  let last: string | undefined
+
+  async function drain() {
+    const item = next
+    if (!item) return
+    next = undefined
+    current = item
+    try {
+      await item.run()
+      last = item.key
+    } catch (err) {
+      report(err)
+    }
+    current = undefined
+    if (next) void drain()
+  }
+
+  return {
+    push(item: Snapshot, force = false) {
+      if (!force && item.key === last && !current) return
+      if (!force && item.key === current?.key && !next) return
+      next = item
+      if (!current) void drain()
+    },
+  }
+}
diff --git a/packages/kilo-console/src/routes/projects/project-console-presence.test.ts b/packages/kilo-console/src/routes/projects/project-console-presence.test.ts
new file mode 100644
index 0000000000..ccaef85a31
--- /dev/null
+++ b/packages/kilo-console/src/routes/projects/project-console-presence.test.ts
@@ -0,0 +1,69 @@
+/**
+ * Contract test for the presence snapshot logic in ProjectConsoleRoute.tsx.
+ *
+ * The route is a large Solid component that cannot be mounted in a unit test,
+ * so these source assertions pin the load-bearing presence behaviour instead:
+ * the console is a dashboard viewer (always inactive, never reports visible
+ * sessions), the attached union covers the selected session plus every terminal
+ * session, the sender serializes snapshots and forced check-ins, and cleanup
+ * reuses the exact url+dir the last regular snapshot used to queue a final empty
+ * snapshot.
+ */
+
+import { describe, expect, test } from "bun:test"
+import fs from "node:fs"
+import path from "node:path"
+
+const ROUTE_FILE = path.resolve(import.meta.dir, "./ProjectConsoleRoute.tsx")
+
+/** Collapse whitespace so multi-line expressions match regardless of formatting. */
+function flat(source: string) {
+  return source.replace(/\s+/g, " ").replace(/\( /g, "(").replace(/ \)/g, ")").replace(/,\)/g, ")")
+}
+
+describe("project console presence contract", () => {
+  test("snapshots always report an inactive viewer with no visible sessions", () => {
+    const content = fs.readFileSync(ROUTE_FILE, "utf-8")
+    expect(content).toContain("const viewerId = crypto.randomUUID()")
+    expect(flat(content)).toContain(
+      "run: async () => { await viewProjectSessions(input, { id: viewerId, active: false }, [...ids], []) }",
+    )
+    expect(content).not.toContain("active: true")
+  })
+
+  test("attached union includes the selected session and every terminal session", () => {
+    const content = fs.readFileSync(ROUTE_FILE, "utf-8")
+    expect(content).toContain("const selected = activeSessionID()")
+    expect(content).toContain("const ids = new Set<string>()")
+    expect(content).toContain("if (selected) ids.add(selected)")
+    expect(flat(content)).toContain(
+      "for (const item of terminals()) { const id = sessionID(item) if (id) ids.add(id) }",
+    )
+  })
+
+  test("snapshots record the url+dir they were sent with", () => {
+    const content = fs.readFileSync(ROUTE_FILE, "utf-8")
+    expect(content).toContain("let lastInput: { url: string; dir: string } | undefined")
+    expect(content).toContain("const input = { url: base.url, dir: data.project.worktree }")
+    expect(content).toContain("lastInput = input")
+  })
+
+  test("routes reactive snapshots and forced check-ins through the serialized sender", () => {
+    const content = fs.readFileSync(ROUTE_FILE, "utf-8")
+    expect(content).toContain('import { sender } from "./project-console-presence-sender"')
+    expect(content).toContain("const queue = sender")
+    expect(content).toContain("function sendSnapshot(force = false)")
+    expect(content).toContain("queue.push(")
+    expect(content).toContain("createEffect(() => sendSnapshot())")
+    expect(content).toContain("const checkin = window.setInterval(() => sendSnapshot(true), 60_000)")
+    expect(content).toContain("window.clearInterval(checkin)")
+  })
+
+  test("cleanup queues a final empty snapshot using the last snapshot's url+dir", () => {
+    const content = flat(fs.readFileSync(ROUTE_FILE, "utf-8"))
+    expect(content).toContain(
+      'window.clearInterval(checkin) if (lastInput) { const input = lastInput queue.push({ key: input.url + "|" + input.dir + "|", run: async () => { await viewProjectSessions(input, { id: viewerId, active: false }, [], []) }, }, true) }',
+    )
+    expect(content).not.toContain("dir: base.dir")
+  })
+})
diff --git a/packages/kilo-vscode/src/KiloProvider.ts b/packages/kilo-vscode/src/KiloProvider.ts
index 56f6beb127..7f8a2f0650 100644
--- a/packages/kilo-vscode/src/KiloProvider.ts
+++ b/packages/kilo-vscode/src/KiloProvider.ts
@@ -502,8 +502,21 @@ export class KiloProvider implements vscode.WebviewViewProvider, TelemetryProper
   }
   private focusSession(id?: string): void {
     this.streams.focus(id)
-    if (id) this.connectionService.registerFocused(this.instanceId, id)
-    else this.connectionService.unregisterFocused(this.instanceId)
+    this.registerPresence()
+  }
+
+  /**
+   * Report presence for this provider: the focused session is visible, and
+   * open local tab sessions (plus the focused one) stay attached even while
+   * the view is hidden.
+   */
+  private registerPresence(): void {
+    if (this.opts.disableViewedRegistration) return
+    const focused = this.streams.focused
+    this.connectionService.registerVisible(this.instanceId, focused ? [focused] : [])
+    const attached = new Set(this.openSessionIds)
+    if (focused) attached.add(focused)
+    this.connectionService.registerAttached(this.instanceId, [...attached])
   }
 
   public setStreamVisibility(active: boolean): void {
@@ -735,9 +748,12 @@ export class KiloProvider implements vscode.WebviewViewProvider, TelemetryProper
 
     this.setupWebviewMessageHandler(panel.webview)
     this.viewStateDisposable?.dispose()
-    this.viewStateDisposable = this.visibleTaskStreams.bindPanel(panel, () =>
-      this.focusSession(panel.active ? this.currentSession?.id : undefined),
-    )
+    this.viewStateDisposable = this.visibleTaskStreams.bindPanel(panel, () => {
+      if (this.opts.disableViewedRegistration) return
+      const id = this.contextSessionID
+      this.streams.focus(panel.visible ? id : undefined)
+      this.connectionService.registerVisible(this.instanceId, panel.visible && id ? [id] : [])
+    })
     this.initializeConnection()
   }
 
@@ -832,7 +848,7 @@ export class KiloProvider implements vscode.WebviewViewProvider, TelemetryProper
     for (const [key, session] of this.draftSessions) {
       if (next.has(session.sid) || session.expires <= now) this.draftSessions.delete(key)
     }
-    this.connectionService.registerOpen(this.instanceId, ids)
+    this.registerPresence()
     this.recoverPendingPrompts()
   }
 
@@ -4401,8 +4417,9 @@ export class KiloProvider implements vscode.WebviewViewProvider, TelemetryProper
    */
   dispose(): void {
     this.unsubscribeRemote?.()
-    this.focusSession()
-    this.connectionService.registerOpen(this.instanceId, [])
+    this.streams.focus(undefined)
+    this.connectionService.unregisterVisible(this.instanceId)
+    this.connectionService.unregisterAttached(this.instanceId)
     this.statsPoller?.stop()
     this.statsGitOps?.dispose()
     this.unsubscribeEvent?.()
diff --git a/packages/kilo-vscode/src/agent-manager/AgentManagerProvider.ts b/packages/kilo-vscode/src/agent-manager/AgentManagerProvider.ts
index a40840eea6..97351e1cdf 100644
--- a/packages/kilo-vscode/src/agent-manager/AgentManagerProvider.ts
+++ b/packages/kilo-vscode/src/agent-manager/AgentManagerProvider.ts
@@ -27,6 +27,7 @@ import { startVscodeRunTask } from "./run/task"
 import { RunController } from "./run/controller"
 import { handleRunMessage } from "./run/message"
 import { forkSession } from "./fork-session"
+import { AgentManagerVisiblePresence } from "./am-visible-presence"
 import { continueInWorktree } from "./continue-in-worktree"
 import { WorktreeDiffController } from "./worktree-diff-controller"
 import { WorktreeImporter } from "./worktree-importer"
@@ -83,10 +84,13 @@ export class AgentManagerProvider implements Disposable {
   private closing: Promise<void> | undefined
   private onVisibilityChange: ((visible: boolean) => void) | undefined
 
-  /** Session ID most recently loaded via a `loadMessages` message from the webview.
-   *  Updated synchronously — unlike the session provider's currentSession which depends on
-   *  an async `session.get` round-trip and can be stale during rapid tab switches. */
+  /** Session ID most recently loaded via `loadMessages`; updated synchronously. */
   private activeSessionId: string | undefined
+  private visiblePresence = new AgentManagerVisiblePresence(
+    (ids) => this.connectionService.registerVisible("agent-manager", ids),
+    () => this.panel?.visible ?? false,
+    (ids) => this.connectionService.registerAttached("agent-manager", ids),
+  )
   constructor(
     private readonly host: Host,
     private readonly connectionService: KiloConnectionService,
@@ -257,6 +261,7 @@ export class AgentManagerProvider implements Disposable {
     this.onVisibilityChange?.(ctx.visible)
     ctx.onDidChangeVisibility((visible) => {
       this.statsPoller.setVisible(visible)
+      this.visiblePresence.flush()
     })
 
     ctx.sessions.onFollowupAdopted((session, directory) => {
@@ -276,8 +281,7 @@ export class AgentManagerProvider implements Disposable {
         this.prBridge.poller.stop()
         this.diffs.stop()
         this.activeSessionId = undefined
-        this.connectionService.unregisterFocused("agent-manager")
-        this.connectionService.registerOpen("agent-manager", [])
+        this.visiblePresence.clear()
         this.panel = undefined
         this.onVisibilityChange?.(false)
       }
@@ -509,7 +513,6 @@ export class AgentManagerProvider implements Disposable {
 
     if (m.type === "loadMessages") {
       this.activeSessionId = m.sessionID
-      this.connectionService.registerFocused("agent-manager", m.sessionID)
       this.terminalManager.syncOnSessionSwitch(m.sessionID)
       this.prBridge.poller.setActiveWorktreeId(this.state?.getSession(m.sessionID)?.worktreeId ?? undefined)
       return msg
@@ -517,7 +520,7 @@ export class AgentManagerProvider implements Disposable {
 
     if (m.type === "clearSession") {
       this.activeSessionId = undefined
-      this.connectionService.unregisterFocused("agent-manager")
+      this.visiblePresence.setDisplayed(null)
       void Promise.resolve().then(() => {
         if (!this.panel || !this.state) return
         for (const id of this.state.worktreeSessionIds()) {
@@ -535,8 +538,8 @@ export class AgentManagerProvider implements Disposable {
       return msg
     }
 
-    if (m.type === "agentManager.openSessions") {
-      this.connectionService.registerOpen("agent-manager", m.sessionIDs)
+    if (m.type === "agentManager.openSessions" || m.type === "agentManager.visibleSession") {
+      this.visiblePresence.handle(m)
       return null
     }
   }
@@ -1475,10 +1478,6 @@ export class AgentManagerProvider implements Disposable {
     return null
   }
 
-  // ---------------------------------------------------------------------------
-  // Keybindings
-  // ---------------------------------------------------------------------------
-
   private sendKeybindings(): void {
     const keybindings = this.host.extensionKeybindings()
     const bindings = buildKeybindingMap(keybindings, process.platform === "darwin")
@@ -1982,8 +1981,7 @@ export class AgentManagerProvider implements Disposable {
     this.unsubTool?.()
     this.unsubStatus?.()
     this.unsubFont?.()
-    this.connectionService.unregisterFocused("agent-manager")
-    this.connectionService.registerOpen("agent-manager", [])
+    this.visiblePresence.clear()
     this.diffs.stop()
     this.naming.dispose()
     this.statsPoller.stop()
diff --git a/packages/kilo-vscode/src/agent-manager/am-visible-presence.test.ts b/packages/kilo-vscode/src/agent-manager/am-visible-presence.test.ts
new file mode 100644
index 0000000000..9f96bead35
--- /dev/null
+++ b/packages/kilo-vscode/src/agent-manager/am-visible-presence.test.ts
@@ -0,0 +1,132 @@
+import { describe, expect, test } from "bun:test"
+import { AgentManagerVisiblePresence } from "./am-visible-presence"
+
+function setup(initialVisible = true) {
+  const calls: string[][] = []
+  const attached: string[][] = []
+  let visible = initialVisible
+  const presence = new AgentManagerVisiblePresence(
+    (ids) => calls.push(ids),
+    () => visible,
+    (ids) => attached.push(ids),
+  )
+  return {
+    calls,
+    attached,
+    presence,
+    setVisible(value: boolean) {
+      visible = value
+    },
+  }
+}
+
+describe("AgentManagerVisiblePresence", () => {
+  test("registers the displayed id while the panel is visible", () => {
+    const { calls, presence } = setup(true)
+
+    presence.setDisplayed("ses_1")
+
+    expect(calls.at(-1)).toEqual(["ses_1"])
+  })
+
+  test("flush registers empty when the panel is hidden", () => {
+    const { calls, presence, setVisible } = setup(true)
+    presence.setDisplayed("ses_1")
+
+    setVisible(false)
+    presence.flush()
+
+    expect(calls.at(-1)).toEqual([])
+  })
+
+  test("flush clears attached when the panel is hidden", () => {
+    const { attached, presence, setVisible } = setup(true)
+    presence.handle({ type: "agentManager.openSessions", sessionIDs: ["ses_1", "ses_2"] })
+
+    setVisible(false)
+    presence.flush()
+
+    expect(attached.at(-1)).toEqual([])
+  })
+
+  test("flush re-registers attached when the panel becomes visible again", () => {
+    const { attached, presence, setVisible } = setup(true)
+    presence.handle({ type: "agentManager.openSessions", sessionIDs: ["ses_1", "ses_2"] })
+
+    setVisible(false)
+    presence.flush()
+    setVisible(true)
+    presence.flush()
+
+    expect(attached.at(-1)).toEqual(["ses_1", "ses_2"])
+  })
+
+  test("setDisplayed(null) registers empty even while visible", () => {
+    const { calls, presence } = setup(true)
+    presence.setDisplayed("ses_1")
+
+    presence.setDisplayed(null)
+
+    expect(calls.at(-1)).toEqual([])
+  })
+
+  test("flush after visibility returns re-registers the retained id", () => {
+    const { calls, presence, setVisible } = setup(false)
+    presence.setDisplayed("ses_1")
+    expect(calls.at(-1)).toEqual([])
+
+    setVisible(true)
+    presence.flush()
+
+    expect(calls.at(-1)).toEqual(["ses_1"])
+  })
+
+  test("setDisplayed(null) prevents a stale id from re-registering on a later flush", () => {
+    const { calls, presence, setVisible } = setup(true)
+    presence.setDisplayed("ses_1")
+
+    setVisible(false)
+    presence.setDisplayed(null)
+    setVisible(true)
+    presence.flush()
+
+    expect(calls.at(-1)).toEqual([])
+  })
+
+  test("handle routes openSessions to attached and visibleSession to visible", () => {
+    const { calls, attached, presence } = setup(true)
+
+    presence.handle({ type: "agentManager.openSessions", sessionIDs: ["ses_1", "ses_2"] })
+    presence.handle({ type: "agentManager.visibleSession", sessionID: "ses_1" })
+
+    expect(attached.at(-1)).toEqual(["ses_1", "ses_2"])
+    expect(calls.at(-1)).toEqual(["ses_1"])
+  })
+
+  test("handle while hidden stores state but registers empty", () => {
+    const { calls, attached, presence, setVisible } = setup(false)
+
+    presence.handle({ type: "agentManager.openSessions", sessionIDs: ["ses_1"] })
+    presence.handle({ type: "agentManager.visibleSession", sessionID: "ses_1" })
+
+    expect(calls.at(-1)).toEqual([])
+    expect(attached.at(-1)).toEqual([])
+
+    setVisible(true)
+    presence.flush()
+
+    expect(calls.at(-1)).toEqual(["ses_1"])
+    expect(attached.at(-1)).toEqual(["ses_1"])
+  })
+
+  test("clear empties both the visible and attached registrations", () => {
+    const { calls, attached, presence } = setup(true)
+    presence.setDisplayed("ses_1")
+    presence.handle({ type: "agentManager.openSessions", sessionIDs: ["ses_1"] })
+
+    presence.clear()
+
+    expect(calls.at(-1)).toEqual([])
+    expect(attached.at(-1)).toEqual([])
+  })
+})
diff --git a/packages/kilo-vscode/src/agent-manager/am-visible-presence.ts b/packages/kilo-vscode/src/agent-manager/am-visible-presence.ts
new file mode 100644
index 0000000000..935ab174ce
--- /dev/null
+++ b/packages/kilo-vscode/src/agent-manager/am-visible-presence.ts
@@ -0,0 +1,51 @@
+/** Vscode-free presence state for the Agent Manager.
+ *
+ * Owns the displayed session id and the open-tab session set. Both are gated
+ * on panel visibility: when the panel is hidden (retainContextWhenHidden
+ * keeps the webview alive), flush() clears both registrations so the retained
+ * webview's reactive updates cannot keep stale sessions attached or visible.
+ * When the panel returns, flush() re-registers from stored state. */
+
+type Register = (ids: string[]) => void
+
+type PresenceMessage =
+  | { type: "agentManager.openSessions"; sessionIDs: string[] }
+  | { type: "agentManager.visibleSession"; sessionID: string | null }
+
+export class AgentManagerVisiblePresence {
+  private id: string | null = null
+  private open: string[] = []
+  constructor(
+    private readonly register: Register,
+    private readonly panelVisible: () => boolean,
+    private readonly registerAttached: Register,
+  ) {}
+
+  setDisplayed(id: string | null): void {
+    this.id = id
+    this.flush()
+  }
+
+  flush(): void {
+    if (this.panelVisible()) {
+      this.register(this.id ? [this.id] : [])
+      this.registerAttached(this.open)
+    } else {
+      this.register([])
+      this.registerAttached([])
+    }
+  }
+
+  handle(m: PresenceMessage): void {
+    if (m.type === "agentManager.openSessions") this.open = m.sessionIDs
+    else this.id = m.sessionID
+    this.flush()
+  }
+
+  clear(): void {
+    this.id = null
+    this.open = []
+    this.register([])
+    this.registerAttached([])
+  }
+}
diff --git a/packages/kilo-vscode/src/agent-manager/types.ts b/packages/kilo-vscode/src/agent-manager/types.ts
index 0476f4a290..528abb6491 100644
--- a/packages/kilo-vscode/src/agent-manager/types.ts
+++ b/packages/kilo-vscode/src/agent-manager/types.ts
@@ -564,6 +564,11 @@ interface OpenSessionsIn {
   sessionIDs: string[]
 }
 
+interface VisibleSessionIn {
+  type: "agentManager.visibleSession"
+  sessionID: string | null
+}
+
 interface OpenFileIn {
   type: "agentManager.openFile"
   sessionId: string
@@ -809,6 +814,7 @@ export type AgentManagerInMessage =
   | RefreshPRIn
   | OpenPRIn
   | OpenSessionsIn
+  | VisibleSessionIn
   | OpenFileIn
   | GenericOpenFileIn
   | PreviewImageIn
diff --git a/packages/kilo-vscode/src/agent-manager/vscode-host.ts b/packages/kilo-vscode/src/agent-manager/vscode-host.ts
index 24d9640877..9a2a3ef315 100644
--- a/packages/kilo-vscode/src/agent-manager/vscode-host.ts
+++ b/packages/kilo-vscode/src/agent-manager/vscode-host.ts
@@ -96,6 +96,7 @@ export class VscodeHost implements Host {
       snapshotInitialization: SNAPSHOT_INITIALIZATION,
       slimEditMetadata: true,
       worktreeDirectories: () => opts.worktreeDirectories?.() ?? [],
+      disableViewedRegistration: true,
     })
     if (this.diffVirtual) {
       provider.setDiffVirtualProvider(this.diffVirtual)
diff --git a/packages/kilo-vscode/src/kilo-provider/options.ts b/packages/kilo-vscode/src/kilo-provider/options.ts
index 32f5d3793c..f32caa4736 100644
--- a/packages/kilo-vscode/src/kilo-provider/options.ts
+++ b/packages/kilo-vscode/src/kilo-provider/options.ts
@@ -5,4 +5,6 @@ export type KiloProviderOptions = {
   slimEditMetadata?: boolean
   tabTitle?: (title: string) => void
   worktreeDirectories?: () => string[]
+  /** Composite hosts (Agent Manager) own viewed/presence registration themselves. */
+  disableViewedRegistration?: boolean
 }
diff --git a/packages/kilo-vscode/src/services/cli-backend/connection-service.test.ts b/packages/kilo-vscode/src/services/cli-backend/connection-service.test.ts
index afb1a3d2ec..17420f7bc6 100644
--- a/packages/kilo-vscode/src/services/cli-backend/connection-service.test.ts
+++ b/packages/kilo-vscode/src/services/cli-backend/connection-service.test.ts
@@ -40,9 +40,9 @@ describe("KiloConnectionService clients", () => {
 })
 
 describe("KiloConnectionService viewed sessions", () => {
-  test("keeps Agent Manager sessions when sidebar focus changes during a flush", async () => {
+  test("keeps Agent Manager sessions when sidebar visibility changes during a flush", async () => {
     const service = new KiloConnectionService({} as any)
-    const calls: Array<{ focused: string[]; open?: string[] }> = []
+    const calls: Array<{ viewer: { id: string; active: boolean }; attached: string[]; visible: string[] }> = []
     let release!: () => void
     const gate = new Promise<void>((resolve) => {
       release = resolve
@@ -50,10 +50,9 @@ describe("KiloConnectionService viewed sessions", () => {
     let active = 0
     let max = 0
 
-    ;(service as any).remoteService = { getState: () => ({ enabled: true }) }
     ;(service as any).client = {
       session: {
-        viewed: async (input: { focused: string[]; open?: string[] }) => {
+        viewed: async (input: { viewer: { id: string; active: boolean }; attached: string[]; visible: string[] }) => {
           calls.push(input)
           active += 1
           max = Math.max(max, active)
@@ -63,23 +62,91 @@ describe("KiloConnectionService viewed sessions", () => {
       },
     }
 
-    service.registerFocused("agent-manager", "am-1")
-    service.registerOpen("agent-manager", ["am-1", "am-2"])
+    service.registerVisible("agent-manager", ["am-1"])
+    service.registerAttached("agent-manager", ["am-1", "am-2"])
     await Bun.sleep(175)
-    expect(calls).toEqual([{ focused: ["am-1"], open: ["am-2"] }])
+    expect(calls).toHaveLength(1)
+    expect([...calls[0].visible].sort()).toEqual(["am-1"])
+    expect([...calls[0].attached].sort()).toEqual(["am-1", "am-2"])
 
-    service.registerFocused("sidebar", "side-1")
+    service.registerVisible("sidebar", ["side-1"])
     await Bun.sleep(175)
     expect(calls).toHaveLength(1)
 
     release()
     await Bun.sleep(10)
     expect(max).toBe(1)
-    expect(calls[1]).toEqual({ focused: ["am-1", "side-1"], open: ["am-2"] })
+    expect([...calls[1].visible].sort()).toEqual(["am-1", "side-1"])
+    expect([...calls[1].attached].sort()).toEqual(["am-1", "am-2", "side-1"])
 
-    service.unregisterFocused("sidebar")
+    service.registerVisible("sidebar", [])
     await Bun.sleep(175)
-    expect(calls[2]).toEqual({ focused: ["am-1"], open: ["am-2"] })
+    expect([...calls[2].visible].sort()).toEqual(["am-1"])
+    expect([...calls[2].attached].sort()).toEqual(["am-1", "am-2"])
+  })
+
+  test("window focus gates viewer.active but not attachment", async () => {
+    const window = vscode.window as unknown as {
+      state: { focused: boolean }
+      onDidChangeWindowState: (listener: (ws: { focused: boolean }) => void) => { dispose(): void }
+    }
+    const original = window.onDidChangeWindowState
+    let listener: ((ws: { focused: boolean }) => void) | undefined
+    window.onDidChangeWindowState = (cb) => {
+      listener = cb
+      return { dispose: () => {} }
+    }
+
+    try {
+      const service = new KiloConnectionService({} as any)
+      const calls: Array<{ viewer: { id: string; active: boolean }; attached: string[]; visible: string[] }> = []
+      ;(service as any).client = {
+        session: {
+          viewed: async (input: (typeof calls)[number]) => {
+            calls.push(input)
+          },
+        },
+      }
+
+      service.registerVisible("sidebar", ["ses-1"])
+      service.registerAttached("sidebar", ["ses-1", "ses-2"])
+      await Bun.sleep(175)
+      expect(calls).toHaveLength(1)
+      expect(calls[0].viewer.active).toBe(true)
+
+      listener!({ focused: false })
+      await Bun.sleep(175)
+      expect(calls).toHaveLength(2)
+      expect(calls[1].viewer.active).toBe(false)
+      expect([...calls[1].visible].sort()).toEqual(["ses-1"])
+      expect([...calls[1].attached].sort()).toEqual(["ses-1", "ses-2"])
+    } finally {
+      window.onDidChangeWindowState = original
+    }
+  })
+
+  test("sends snapshots while remote control is disabled", async () => {
+    const service = new KiloConnectionService({} as any)
+    const calls: Array<{ viewer: { id: string; active: boolean }; attached: string[]; visible: string[] }> = []
+    ;(service as any).client = {
+      session: {
+        viewed: async (input: (typeof calls)[number]) => {
+          calls.push(input)
+        },
+      },
+    }
+    service.setRemoteService({
+      getState: () => ({ enabled: false, connected: false }),
+      onChange: () => () => {},
+    } as any)
+
+    service.registerVisible("sidebar", ["ses-1"])
+    service.registerAttached("agent-manager", ["ses-2"])
+    await Bun.sleep(175)
+
+    expect(calls).toHaveLength(1)
+    expect([...calls[0].visible].sort()).toEqual(["ses-1"])
+    expect([...calls[0].attached].sort()).toEqual(["ses-1", "ses-2"])
   })
 })
 
diff --git a/packages/kilo-vscode/src/services/cli-backend/connection-service.ts b/packages/kilo-vscode/src/services/cli-backend/connection-service.ts
index f5d97798b3..7a7e120965 100644
--- a/packages/kilo-vscode/src/services/cli-backend/connection-service.ts
+++ b/packages/kilo-vscode/src/services/cli-backend/connection-service.ts
@@ -57,6 +57,12 @@ function isNotFound(err: unknown) {
   return false
 }
 
+function sameSet(a: Set<string>, b: Set<string>): boolean {
+  if (a.size !== b.size) return false
+  for (const id of a) if (!b.has(id)) return false
+  return true
+}
+
 // Poll /global/health every 10 seconds.
 // This provides a second detection channel for server death independent of the SSE heartbeat.
 const HEALTH_POLL_INTERVAL_MS = 10_000
@@ -111,10 +117,14 @@ export class KiloConnectionService {
    */
   private readonly messageSessionIdsByMessageId: Map<string, string> = new Map()
 
-  /** Provider key → single focused session ID. */
-  private readonly focused: Map<string, string> = new Map()
-  /** Provider key → all open (background) session IDs. */
-  private readonly opened: Map<string, string[]> = new Map()
+  private readonly viewerId = crypto.randomUUID()
+  private active = true
+  private windowStateDisposable: vscode.Disposable | null = null
+  private checkinTimer: ReturnType<typeof setInterval> | null = null
+  /** Provider key → attached (retained for remote control) session IDs. */
+  private readonly attached: Map<string, Set<string>> = new Map()
+  /** Provider key → visibly rendered session IDs. */
+  private readonly visible: Map<string, Set<string>> = new Map()
   private debounceTimer: ReturnType<typeof setTimeout> | null = null
   private viewedSending = false
   private viewedDirty = false
@@ -129,6 +139,11 @@ export class KiloConnectionService {
       } satisfies Pick<vscode.Memento, "get" | "update">)
     this.sandboxPreference = new SandboxPreference(state)
     this.serverManager = new ServerManager(context, (code) => this.handleServerExit(code))
+    this.active = vscode.window.state.focused
+    this.windowStateDisposable = vscode.window.onDidChangeWindowState((ws) => {
+      this.active = ws.focused
+      this.flushViewed()
+    })
   }
 
   /**
@@ -293,14 +308,15 @@ export class KiloConnectionService {
     for (const [mid, sid] of this.messageSessionIdsByMessageId) {
       if (sid === sessionId) this.messageSessionIdsByMessageId.delete(mid)
     }
-    for (const [key, sid] of this.focused) {
-      if (sid === sessionId) this.focused.delete(key)
+    for (const [key, ids] of this.attached) {
+      if (!ids.has(sessionId)) continue
+      ids.delete(sessionId)
+      if (ids.size === 0) this.attached.delete(key)
     }
-    for (const [key, ids] of this.opened) {
-      if (!ids.includes(sessionId)) continue
-      const next = ids.filter((id) => id !== sessionId)
-      if (next.length === 0) this.opened.delete(key)
-      else this.opened.set(key, next)
+    for (const [key, ids] of this.visible) {
+      if (!ids.has(sessionId)) continue
+      ids.delete(sessionId)
+      if (ids.size === 0) this.visible.delete(key)
     }
     this.flushViewed()
   }
@@ -584,38 +600,49 @@ export class KiloConnectionService {
   }
 
   /**
-   * Register the session a provider is actively viewing (focused).
-   * After any change the aggregated set is sent to the server (debounced).
+   * Register the sessions a provider retains for remote control (attached).
+   * Sent to the server (debounced) regardless of remote-control enablement.
    */
-  registerFocused(key: string, sessionID: string): void {
-    if (this.focused.get(key) === sessionID) return
-    this.focused.set(key, sessionID)
+  registerAttached(key: string, ids: string[]): void {
+    const next = new Set(ids)
+    const prev = this.attached.get(key)
+    if (prev && sameSet(prev, next)) return
+    this.attached.set(key, next)
     this.flushViewed()
   }
 
   /**
-   * Unregister a provider's focused session (e.g. on dispose, hidden, or clearSession).
+   * Unregister a provider's attached sessions (e.g. on dispose or clear).
    */
-  unregisterFocused(key: string): void {
-    if (!this.focused.has(key)) return
-    this.focused.delete(key)
+  unregisterAttached(key: string): void {
+    if (!this.attached.has(key)) return
+    this.attached.delete(key)
     this.flushViewed()
   }
 
   /**
-   * Register the open (background tab) session IDs for a provider.
-   * Sessions that appear in both focused and open are reported as focused only.
+   * Register the sessions a provider visibly renders (visible).
+   * Visible sessions are also reported as attached.
    */
-  registerOpen(key: string, ids: string[]): void {
-    const prev = this.opened.get(key)
-    if (prev && prev.length === ids.length && prev.every((v, i) => v === ids[i])) return
-    this.opened.set(key, ids)
+  registerVisible(key: string, ids: string[]): void {
+    const next = new Set(ids)
+    const prev = this.visible.get(key)
+    if (prev && sameSet(prev, next)) return
+    this.visible.set(key, next)
     this.flushViewed()
   }
 
-  /** Debounced: send the aggregated focused + open session IDs to the server. */
+  /**
+   * Unregister a provider's visible sessions (e.g. on hide, clear, or dispose).
+   */
+  unregisterVisible(key: string): void {
+    if (!this.visible.has(key)) return
+    this.visible.delete(key)
+    this.flushViewed()
+  }
+
+  /** Debounced: send the aggregated attached + visible snapshot to the server. Works even when remote control is disabled. */
   flushViewed(): void {
-    if (!this.isRemoteEnabled()) return
     if (this.debounceTimer) clearTimeout(this.debounceTimer)
     this.debounceTimer = setTimeout(() => {
       this.debounceTimer = null
@@ -624,28 +651,21 @@ export class KiloConnectionService {
   }
 
   private sendViewed(): void {
-    if (!this.isRemoteEnabled()) {
-      this.viewedDirty = false
-      return
-    }
     if (this.viewedSending) {
       this.viewedDirty = true
       return
     }
     if (!this.client) return
 
-    const focus = new Set(this.focused.values())
-    const open = new Set<string>()
-    for (const ids of this.opened.values()) {
-      for (const id of ids) {
-        if (!focus.has(id)) open.add(id)
-      }
-    }
+    const visible = new Set<string>()
+    for (const ids of this.visible.values()) for (const id of ids) visible.add(id)
+    const attached = new Set<string>(visible)
+    for (const ids of this.attached.values()) for (const id of ids) attached.add(id)
 
     this.viewedSending = true
     this.viewedDirty = false
     void this.client.session
-      .viewed({ focused: [...focus], open: [...open] })
+      .viewed({ viewer: { id: this.viewerId, active: this.active }, attached: [...attached], visible: [...visible] })
       .catch((err) => console.warn("[Kilo New] ConnectionService: viewed flush failed:", err))
       .finally(() => {
         this.viewedSending = false
@@ -674,12 +694,23 @@ export class KiloConnectionService {
     this.permissionDirectories.clear()
     this.questionDirectories.clear()
     this.questionRevision += 1
-    this.focused.clear()
-    this.opened.clear()
+    if (this.client?.session?.viewed) {
+      void this.client.session
+        .viewed({ viewer: { id: this.viewerId, active: false }, attached: [], visible: [] })
+        .catch(() => {})
+    }
+    this.attached.clear()
+    this.visible.clear()
     if (this.debounceTimer) {
       clearTimeout(this.debounceTimer)
       this.debounceTimer = null
     }
+    if (this.checkinTimer) {
+      clearInterval(this.checkinTimer)
+      this.checkinTimer = null
+    }
+    this.windowStateDisposable?.dispose()
+    this.windowStateDisposable = null
     this.viewedDirty = false
     this.unsubRemote?.()
     this.unsubRemote = null
@@ -747,6 +778,7 @@ export class KiloConnectionService {
 
   private resetConnection(): void {
     this.stopHealthPoll()
+    this.stopCheckin()
     const sse = this.sseClient
     this.sseClient = null
     sse?.disconnect()
@@ -837,6 +869,7 @@ export class KiloConnectionService {
         resolveConnected?.()
         resolveConnected = null
         rejectConnected = null
+        this.flushViewed()
         return
       }
 
@@ -851,10 +884,24 @@ export class KiloConnectionService {
 
     await connectedPromise
 
+    this.startCheckin()
     // Start the independent health poll once we are confirmed connected.
     this.startHealthPoll(config.baseUrl, config.password)
   }
 
+  private startCheckin(): void {
+    this.stopCheckin()
+    this.checkinTimer = setInterval(() => this.flushViewed(), 60_000)
+    this.checkinTimer.unref?.()
+  }
+
+  private stopCheckin(): void {
+    if (this.checkinTimer) {
+      clearInterval(this.checkinTimer)
+      this.checkinTimer = null
+    }
+  }
+
   private handlePermissionEvent(event: SSEPayload, directory?: string): void {
     if (event.type === "permission.asked" && directory) {
       this.recordPermissionDirectory(event.properties.id, directory)
diff --git a/packages/kilo-vscode/tests/setup/vscode-mock.ts b/packages/kilo-vscode/tests/setup/vscode-mock.ts
index d85485821f..a5914f7bff 100644
--- a/packages/kilo-vscode/tests/setup/vscode-mock.ts
+++ b/packages/kilo-vscode/tests/setup/vscode-mock.ts
@@ -80,6 +80,8 @@ const mockVscode = {
   },
   window: {
     activeTextEditor: undefined,
+    state: { focused: true },
+    onDidChangeWindowState: () => ({ dispose: noop }),
     activeNotebookEditor: undefined,
     visibleTextEditors: [],
     visibleNotebookEditors: [],
diff --git a/packages/kilo-vscode/tests/unit/agent-manager-arch.test.ts b/packages/kilo-vscode/tests/unit/agent-manager-arch.test.ts
index 574b345bfd..efce41c2ba 100644
--- a/packages/kilo-vscode/tests/unit/agent-manager-arch.test.ts
+++ b/packages/kilo-vscode/tests/unit/agent-manager-arch.test.ts
@@ -216,8 +216,12 @@ describe("Agent Manager Provider Messages", () => {
 
   it("clears remote session registrations when the panel closes", () => {
     const body = getMethodBody("attachPanel")
-    expect(body).toContain('this.connectionService.unregisterFocused("agent-manager")')
-    expect(body).toContain('this.connectionService.registerOpen("agent-manager", [])')
+    // Presence must be cleared via visiblePresence.clear() — a direct
+    // registerVisible("agent-manager", []) would leave a stale displayed id
+    // that re-registers on the next flush after the panel reopens.
+    expect(body).toContain("this.visiblePresence.clear()")
+    expect(body).not.toContain('this.connectionService.registerVisible("agent-manager"')
+    expect(body).not.toContain('this.connectionService.registerAttached("agent-manager"')
     expect(body).toContain("this.activeSessionId = undefined")
   })
 
diff --git a/packages/kilo-vscode/tests/unit/agent-manager-remote-sessions.test.ts b/packages/kilo-vscode/tests/unit/agent-manager-remote-sessions.test.ts
new file mode 100644
index 0000000000..c31c333663
--- /dev/null
+++ b/packages/kilo-vscode/tests/unit/agent-manager-remote-sessions.test.ts
@@ -0,0 +1,28 @@
+import { expect, test } from "bun:test"
+import fs from "node:fs"
+import path from "node:path"
+import { visible } from "../../webview-ui/agent-manager/remote-sessions"
+
+const APP = path.resolve(import.meta.dir, "../../webview-ui/agent-manager/AgentManagerApp.tsx")
+
+function flat(source: string) {
+  return source.replace(/\s+/g, " ")
+}
+
+test("reports a real session only while its chat surface is displayed", () => {
+  expect(visible("ses_1", false)).toBe("ses_1")
+  expect(visible("ses_1", true)).toBeNull()
+})
+
+test("does not report synthetic pending or cloud preview IDs", () => {
+  expect(visible("pending:1", false)).toBeNull()
+  expect(visible("cloud:1", false)).toBeNull()
+})
+
+test("blocks visible presence while setup or an empty pane covers chat", () => {
+  const source = flat(fs.readFileSync(APP, "utf-8"))
+  expect(source).toContain(
+    "visible( session.currentSessionID(), !!terms.activeId() || reviewActive() || history() || !!overlay() || contextEmpty(), )",
+  )
+  expect(source).toContain("<Show when={overlay()}>")
+})
diff --git a/packages/kilo-vscode/tests/unit/kilo-provider-load-messages.test.ts b/packages/kilo-vscode/tests/unit/kilo-provider-load-messages.test.ts
index db6fbb75f5..e3f39c994e 100644
--- a/packages/kilo-vscode/tests/unit/kilo-provider-load-messages.test.ts
+++ b/packages/kilo-vscode/tests/unit/kilo-provider-load-messages.test.ts
@@ -199,9 +199,10 @@ function createConnection(client: ReturnType<typeof createClient>) {
     recordMessageSessionId: () => undefined,
     notifyNotificationDismissed: () => undefined,
     pruneSession: () => undefined,
-    registerFocused: () => undefined,
-    unregisterFocused: () => undefined,
-    registerOpen: () => undefined,
+    registerVisible: () => undefined,
+    unregisterVisible: () => undefined,
+    registerAttached: () => undefined,
+    unregisterAttached: () => undefined,
   }
 }
 
diff --git a/packages/kilo-vscode/tests/unit/presence-registration-contract.test.ts b/packages/kilo-vscode/tests/unit/presence-registration-contract.test.ts
new file mode 100644
index 0000000000..e97cf52c43
--- /dev/null
+++ b/packages/kilo-vscode/tests/unit/presence-registration-contract.test.ts
@@ -0,0 +1,180 @@
+/**
+ * Source contract tests for session-presence registration.
+ *
+ * Static analysis — reads KiloProvider.ts, AgentManagerProvider.ts,
+ * vscode-host.ts, and connection-service.ts and verifies the locked
+ * viewed/presence behavior from the presence plan:
+ *
+ * - Editor panels register visible keyed on `panel.visible` and the
+ *   synchronous `contextSessionID`; attachment persists while hidden.
+ * - Embedded Agent Manager providers skip generic viewed registration
+ *   (`disableViewedRegistration`) so sessions are not double-reported.
+ * - The connection service resends the full snapshot on backend reconnect.
+ * - Agent Manager visible presence is routed through
+ *   AgentManagerVisiblePresence so cleanup cannot leave a stale displayed id.
+ *
+ * Protects against accidental removal during Kilo development.
+ */
+
+import { describe, it, expect } from "bun:test"
+import fs from "node:fs"
+import path from "node:path"
+
+const ROOT = path.resolve(import.meta.dir, "../..")
+const KILOPROVIDER_FILE = path.join(ROOT, "src/KiloProvider.ts")
+const AGENT_MANAGER_PROVIDER_FILE = path.join(ROOT, "src/agent-manager/AgentManagerProvider.ts")
+const VSCODE_HOST_FILE = path.join(ROOT, "src/agent-manager/vscode-host.ts")
+const CONNECTION_SERVICE_FILE = path.join(ROOT, "src/services/cli-backend/connection-service.ts")
+
+function readFile(filePath: string): string {
+  return fs.readFileSync(filePath, "utf-8")
+}
+
+describe("KiloProvider editor-panel visible registration contract", () => {
+  const source = readFile(KILOPROVIDER_FILE)
+  // The bindPanel callback installed in resolveWebviewPanel.
+  const match = source.match(
+    /this\.viewStateDisposable = this\.visibleTaskStreams\.bindPanel\(panel, \(\) => \{([\s\S]*?)\n {4}\}\)/,
+  )
+
+  it("binds a view-state callback on the panel", () => {
+    expect(match).not.toBeNull()
+  })
+
+  it("registers visible keyed on panel.visible and the synchronous contextSessionID", () => {
+    // `panel.active` would drop visible-but-inactive split editors, and
+    // `this.currentSession?.id` is populated asynchronously — rapid A→B
+    // navigation must report B without awaiting B's metadata fetch.
+    const body = match![1]
+    expect(body).toContain("this.contextSessionID")
+    expect(body).toContain("panel.visible")
+    expect(body).toContain("this.connectionService.registerVisible(this.instanceId,")
+    expect(body).not.toContain("panel.active")
+    expect(body).not.toContain("this.currentSession")
+  })
+
+  it("does not clear attachment when the panel is hidden", () => {
+    // Hidden editor tabs stay reachable for remote control: the panel
+    // view-state callback must never touch the attached registration
+    // (directly or via focusSession) — attachment is cleared only by the
+    // dispose/clear/delete paths.
+    const body = match![1]
+    expect(body).toContain("this.streams.focus(panel.visible ? id : undefined)")
+    expect(body).not.toContain("registerAttached")
+    expect(body).not.toContain("focusSession")
+  })
+})
+
+describe("KiloProvider disableViewedRegistration contract", () => {
+  const kiloProvider = readFile(KILOPROVIDER_FILE)
+  const vscodeHost = readFile(VSCODE_HOST_FILE)
+
+  it("registerPresence skips viewed registration when the option is set", () => {
+    const match = kiloProvider.match(/private registerPresence\(\): void \{([\s\S]*?)\n {2}\}/)
+    expect(match).not.toBeNull()
+    const body = match![1]
+    const guard = body.indexOf("if (this.opts.disableViewedRegistration) return")
+    const visible = body.indexOf("this.connectionService.registerVisible(this.instanceId,")
+    const attached = body.indexOf("this.connectionService.registerAttached(this.instanceId,")
+    expect(guard).toBeGreaterThanOrEqual(0)
+    expect(visible).toBeGreaterThan(guard)
+    expect(attached).toBeGreaterThan(guard)
+  })
+
+  it("focusSession and trackOpenSessions report through registerPresence", () => {
+    // Both the focused session (visible) and the open local tabs (attached)
+    // funnel into one snapshot so neither write can clobber the other.
+    const focus = kiloProvider.match(/private focusSession\(id\?: string\): void \{([\s\S]*?)\n {2}\}/)
+    expect(focus).not.toBeNull()
+    expect(focus![1]).toContain("this.registerPresence()")
+    const track = kiloProvider.match(/private trackOpenSessions\(ids: string\[\]\): void \{([\s\S]*?)\n {2}\}/)
+    expect(track).not.toBeNull()
+    expect(track![1]).toContain("this.registerPresence()")
+  })
+
+  it("registerPresence attaches the open local tabs plus the focused session", () => {
+    const match = kiloProvider.match(/private registerPresence\(\): void \{([\s\S]*?)\n {2}\}/)
+    expect(match).not.toBeNull()
+    const body = match![1]
+    expect(body).toContain("const attached = new Set(this.openSessionIds)")
+    expect(body).toContain("if (focused) attached.add(focused)")
+  })
+
+  it("the editor-panel view-state callback honors the same option", () => {
+    const match = kiloProvider.match(
+      /this\.viewStateDisposable = this\.visibleTaskStreams\.bindPanel\(panel, \(\) => \{([\s\S]*?)\n {4}\}\)/,
+    )
+    expect(match).not.toBeNull()
+    const guard = match![1].indexOf("if (this.opts.disableViewedRegistration) return")
+    const visible = match![1].indexOf("registerVisible")
+    expect(guard).toBeGreaterThanOrEqual(0)
+    expect(visible).toBeGreaterThan(guard)
+  })
+
+  it("embedded Agent Manager providers disable generic viewed registration", () => {
+    // Each Agent Manager panel hosts a full KiloProvider; the "agent-manager"
+    // keys own presence there, so the embedded provider must not
+    // double-register under its own instanceId.
+    expect(vscodeHost).toContain("disableViewedRegistration: true")
+  })
+})
+
+describe("KiloConnectionService connection snapshot contract", () => {
+  const source = readFile(CONNECTION_SERVICE_FILE)
+
+  it("sends the accumulated snapshot on initial connection and reconnect", () => {
+    const start = source.indexOf('if (sseState === "connected")')
+    const end = source.indexOf('if (!didConnect && sseState === "disconnected")', start)
+    expect(start).toBeGreaterThan(-1)
+    expect(end).toBeGreaterThan(start)
+    const body = source.slice(start, end)
+    expect(body).toContain("this.flushViewed()")
+    expect(body).not.toContain("if (isReconnect)")
+  })
+})
+
+describe("AgentManagerProvider visible-presence contract", () => {
+  const source = readFile(AGENT_MANAGER_PROVIDER_FILE)
+
+  it("routes all agent-manager visible registration through AgentManagerVisiblePresence", () => {
+    // Exactly one direct registerVisible("agent-manager", ...) call site — the
+    // presence callback. Cleanup paths that bypassed it (registering [] without
+    // clearing the displayed id) let a stale id re-register on the next flush.
+    const sites = source.match(/registerVisible\("agent-manager"/g) ?? []
+    expect(sites).toHaveLength(1)
+    expect(source).toMatch(
+      /new AgentManagerVisiblePresence\(\s*\(ids\) => this\.connectionService\.registerVisible\("agent-manager", ids\)/,
+    )
+  })
+
+  it("async shutdown clears both the visible and attached registrations", () => {
+    // clear() resets the displayed id and empties the attached set, so a
+    // stale id cannot re-register on a later flush.
+    const match = source.match(/private async disposeAsync\(\): Promise<void> \{([\s\S]*?)\n {2}\}/)
+    expect(match).not.toBeNull()
+    expect(match![1]).toContain("this.visiblePresence.clear()")
+  })
+
+  it("routes the webview presence messages to visiblePresence.handle", () => {
+    // The webview reports the open tab set (→ attached) and the actually
+    // displayed real session id (null for terminal/review/pending/empty
+    // tabs, → visible); both flow through the presence helper.
+    expect(source).toMatch(
+      /if \(m\.type === "agentManager\.openSessions" \|\| m\.type === "agentManager\.visibleSession"\) \{\s*this\.visiblePresence\.handle\(m\)/,
+    )
+  })
+
+  it("does not let background message loads override webview visibility", () => {
+    const match = source.match(/if \(m\.type === "loadMessages"\) \{([\s\S]*?)\n {4}\}/)
+    expect(match).not.toBeNull()
+    expect(match![1]).not.toContain("visiblePresence.setDisplayed")
+  })
+
+  it("recomputes visible presence when panel visibility changes", () => {
+    // A hidden Agent Manager panel must drop its session from visible (while
+    // keeping it attached); reappearing must re-register the retained id.
+    const match = source.match(/ctx\.onDidChangeVisibility\(\(visible\) => \{([\s\S]*?)\n {4}\}\)/)
+    expect(match).not.toBeNull()
+    expect(match![1]).toContain("this.visiblePresence.flush()")
+  })
+})
diff --git a/packages/kilo-vscode/tests/unit/prompt-send-contract.test.ts b/packages/kilo-vscode/tests/unit/prompt-send-contract.test.ts
index 53fbad2134..3d46126d76 100644
--- a/packages/kilo-vscode/tests/unit/prompt-send-contract.test.ts
+++ b/packages/kilo-vscode/tests/unit/prompt-send-contract.test.ts
@@ -194,9 +194,9 @@ describe("KiloProvider pruneDeletedSession contract", () => {
   })
 
   it("unfocuses the streams when the deleted id matches the focused session", () => {
-    // Without this, connectionService.focused still reports the deleted id to
-    // the backend (viewed.focused), and focusSession() never calls
-    // unregisterFocused for this instance.
+    // Without this, connectionService still reports the deleted id to the
+    // backend as visible, and focusSession() never clears the visible
+    // registration for this instance.
     const match = source.match(/pruneDeletedSession\(sessionID: string\): void \{([\s\S]*?)\n  \}/)
     expect(match).not.toBeNull()
     expect(match![1]).toMatch(/if \(this\.streams\.focused === sessionID\) this\.focusSession\(undefined\)/)
@@ -542,15 +542,15 @@ describe("Cloud import parts cleanup contract", () => {
 describe("KiloConnectionService pruneSession contract", () => {
   const source = readFile(CONNECTION_SERVICE_FILE)
 
-  it("drops the deleted session from focused and opened Maps", () => {
+  it("drops the deleted session from attached and visible Maps", () => {
     // KiloProvider's pruneDeletedSession calls connectionService.pruneSession.
-    // Without clearing focused/opened entries whose value is the deleted id,
-    // the backend keeps receiving viewed.focused with the dead session id and
-    // any background tab opener stays registered for it.
+    // Without clearing attached/visible entries whose value is the deleted id,
+    // the backend keeps receiving the dead session id and any background tab
+    // opener stays registered for it.
     const match = source.match(/pruneSession\(sessionId: string\): void \{([\s\S]*?)\n  \}/)
     expect(match).not.toBeNull()
-    expect(match![1]).toMatch(/this\.focused\.delete\(key\)/)
-    expect(match![1]).toMatch(/this\.opened\.(?:set|delete)/)
+    expect(match![1]).toMatch(/this\.attached\.(?:set|delete)/)
+    expect(match![1]).toMatch(/this\.visible\.(?:set|delete)/)
     expect(match![1]).toMatch(/this\.flushViewed\(\)/)
   })
 })
diff --git a/packages/kilo-vscode/webview-ui/agent-manager/AgentManagerApp.tsx b/packages/kilo-vscode/webview-ui/agent-manager/AgentManagerApp.tsx
index 467cb4fe3e..51efb0d51d 100644
--- a/packages/kilo-vscode/webview-ui/agent-manager/AgentManagerApp.tsx
+++ b/packages/kilo-vscode/webview-ui/agent-manager/AgentManagerApp.tsx
@@ -111,7 +111,7 @@ import {
 } from "../src/utils/draft-store"
 import { reorderTabs, applyTabOrder, firstOrderedTitle } from "./tab-order"
 import { createTabOrderSync } from "./tab-order-sync"
-import { reportRemoteSessions } from "./remote-sessions"
+import { reportRemoteSessions, reportVisibleSession, visible } from "./remote-sessions"
 import { ConstrainDragYAxis } from "../src/components/chat/TabDnd"
 import { isTerminalTabId, createTerminalState, createTerminalHandlers, createTerminalMessageHandler } from "./terminal"
 import { focusCurrentTab, renderTab, renderTerminalLayer, renderNewTabButton } from "./tab-rendering"
@@ -768,6 +768,21 @@ const AgentManagerContent: Component = () => {
     return false
   })
 
+  const overlay = createMemo((): SetupState | null => {
+    const state = setup()
+    const sel = selection()
+    if (state.active && (!state.worktreeId || sel === state.worktreeId)) return state
+    if (typeof sel !== "string" || sel === LOCAL) return null
+    const busy = busyWorktrees().get(sel)
+    if (busy?.reason !== "setting-up") return null
+    const tree = worktrees().find((item) => item.id === sel)
+    return {
+      active: true,
+      message: busy.message ?? "",
+      branch: busy.branch ?? tree?.branch,
+    }
+  })
+
   createEffect(() => {
     const sel = selection()
     if (sel === null) {
@@ -796,7 +811,13 @@ const AgentManagerContent: Component = () => {
     if (reviewActive()) return REVIEW_TAB_ID
     return session.currentSessionID() ?? activePendingId()
   })
-
+  const visibleSession = createMemo(() =>
+    visible(
+      session.currentSessionID(),
+      !!terms.activeId() || reviewActive() || history() || !!overlay() || contextEmpty(),
+    ),
+  )
+  reportVisibleSession(vscode, visibleSession)
   const worktreeLabel = (wt: WorktreeState): string => {
     if (wt.label) return wt.label
     return firstOrderedTitle(sessionsForWorktree(wt.id), worktreeTabOrder()[wt.id], wt.branch)
@@ -2914,54 +2935,29 @@ const AgentManagerContent: Component = () => {
           </div>
         </Show>
 
-        {(() => {
-          // Show setup overlay: either the transient ready/error state for the selected worktree,
-          // or if the selected worktree is still being set up (from busyWorktrees map)
-          const overlayState = (): SetupState | null => {
-            const s = setup()
-            const sel = selection()
-            // Transient ready/error overlay for the selected worktree (or worktree-less setup)
-            if (s.active && (!s.worktreeId || sel === s.worktreeId)) return s
-            // Persistent setup-in-progress for the currently selected worktree
-            if (typeof sel === "string" && sel !== LOCAL) {
-              const busy = busyWorktrees().get(sel)
-              if (busy?.reason === "setting-up") {
-                const wt = worktrees().find((w) => w.id === sel)
-                return {
-                  active: true,
-                  message: busy.message ?? "",
-                  branch: busy.branch ?? wt?.branch,
-                } satisfies SetupState
-              }
-            }
-            return null
-          }
-          return (
-            <Show when={overlayState()}>
-              {(state) => (
-                <div class="am-setup-overlay">
-                  <div class="am-setup-card">
-                    <Icon name="branch" size="large" />
-                    <div class="am-setup-title">
-                      {state().error ? t("agentManager.setup.failed") : t("agentManager.setup.settingUp")}
-                    </div>
-                    <Show when={state().branch}>
-                      <div class="am-setup-branch">{state().branch}</div>
-                    </Show>
-                    <div class="am-setup-status">
-                      <Show when={!state().error} fallback={<Icon name="circle-x" size="small" />}>
-                        <Spinner class="am-setup-spinner" />
-                      </Show>
-                      <span>
-                        {state().errorCode ? t(`agentManager.setup.error.${state().errorCode}`) : state().message}
-                      </span>
-                    </div>
-                  </div>
+        <Show when={overlay()}>
+          {(state) => (
+            <div class="am-setup-overlay">
+              <div class="am-setup-card">
+                <Icon name="branch" size="large" />
+                <div class="am-setup-title">
+                  {state().error ? t("agentManager.setup.failed") : t("agentManager.setup.settingUp")}
                 </div>
-              )}
-            </Show>
-          )
-        })()}
+                <Show when={state().branch}>
+                  <div class="am-setup-branch">{state().branch}</div>
+                </Show>
+                <div class="am-setup-status">
+                  <Show when={!state().error} fallback={<Icon name="circle-x" size="small" />}>
+                    <Spinner class="am-setup-spinner" />
+                  </Show>
+                  <span>
+                    {state().errorCode ? t(`agentManager.setup.error.${state().errorCode}`) : state().message}
+                  </span>
+                </div>
+              </div>
+            </div>
+          )}
+        </Show>
         <Show when={history()}>
           <HistoryView
             onSelectSession={(id) => {
diff --git a/packages/kilo-vscode/webview-ui/agent-manager/remote-sessions.ts b/packages/kilo-vscode/webview-ui/agent-manager/remote-sessions.ts
index cfe5d5cf2c..8dbae4d666 100644
--- a/packages/kilo-vscode/webview-ui/agent-manager/remote-sessions.ts
+++ b/packages/kilo-vscode/webview-ui/agent-manager/remote-sessions.ts
@@ -5,8 +5,17 @@ type Bridge = {
   postMessage(message: { type: "agentManager.openSessions"; sessionIDs: string[] }): void
 }
 
+type VisibleBridge = {
+  postMessage(message: { type: "agentManager.visibleSession"; sessionID: string | null }): void
+}
+
 type Managed = { id: string; worktreeId: string | null }
 
+export function visible(id: string | undefined, blocked: boolean): string | null {
+  if (blocked || !id?.startsWith("ses")) return null
+  return id
+}
+
 export function reportRemoteSessions(
   vscode: Bridge,
   local: Accessor<string[]>,
@@ -20,3 +29,12 @@ export function reportRemoteSessions(
     })
   })
 }
+
+// Report the actually displayed real session id, or null when a terminal,
+// review, pending, or empty tab is shown. Drives only visible presence;
+// retained attached tabs are unaffected.
+export function reportVisibleSession(vscode: VisibleBridge, visible: Accessor<string | null>): void {
+  createEffect(() => {
+    vscode.postMessage({ type: "agentManager.visibleSession", sessionID: visible() })
+  })
+}
diff --git a/packages/kilo-vscode/webview-ui/src/types/messages/webview-messages.ts b/packages/kilo-vscode/webview-ui/src/types/messages/webview-messages.ts
index 326f271bd3..0dfb373ff4 100644
--- a/packages/kilo-vscode/webview-ui/src/types/messages/webview-messages.ts
+++ b/packages/kilo-vscode/webview-ui/src/types/messages/webview-messages.ts
@@ -980,6 +980,11 @@ export interface SidebarOpenSessionsMessage {
   sessionIDs: string[]
 }
 
+export interface AgentManagerVisibleSessionMessage {
+  type: "agentManager.visibleSession"
+  sessionID: string | null
+}
+
 export interface RequestAutoApproveStateMessage {
   type: "requestAutoApproveState"
 }
@@ -1366,6 +1371,7 @@ export type WebviewMessage =
   | SetDefaultBaseBranchRequest
   | AgentManagerOpenSessionsMessage
   | SidebarOpenSessionsMessage
+  | AgentManagerVisibleSessionMessage
   | RequestAutoApproveStateMessage
   | ToggleAutoApproveMessage
   | RequestSandboxStatusMessage
diff --git a/packages/opencode/src/kilo-sessions/kilo-sessions.ts b/packages/opencode/src/kilo-sessions/kilo-sessions.ts
index 277b1eaaec..016e5b9bc1 100644
--- a/packages/opencode/src/kilo-sessions/kilo-sessions.ts
+++ b/packages/opencode/src/kilo-sessions/kilo-sessions.ts
@@ -38,6 +38,12 @@ async function provide<R>(input: { directory: string; fn: () => R }): Promise<R>
   return provide(input)
 }
 
+function same(a: Set<string>, b: Set<string>): boolean {
+  if (a.size !== b.size) return false
+  for (const id of a) if (!b.has(id)) return false
+  return true
+}
+
 export namespace KiloSessions {
   export const Event = {
     RemoteStatusChanged: BusEvent.define(
@@ -203,8 +209,7 @@ export namespace KiloSessions {
   let remote: { conn: RemoteWS.Connection; sender: RemoteSender.Sender } | undefined
   let enabling: Promise<void> | undefined
   let remoteSeq = 0
-  const focused = new Set<string>()
-  const opened = new Set<string>()
+  const attached = new Set<string>()
   const statusSyncs = new Map<string, { running: boolean; dirty: boolean }>()
   const STATUS_TIMEOUT_MS = 3_000
 
@@ -416,8 +421,7 @@ export namespace KiloSessions {
         const statusMap = await AppRuntime.runPromise(SessionStatus.Service.use((svc) => svc.list()))
         const statuses: Record<string, SessionStatus.Info> = Object.fromEntries(statusMap)
         const ids = new Set(Object.keys(statuses))
-        for (const id of focused) ids.add(id)
-        for (const id of opened) ids.add(id)
+        for (const id of attached) ids.add(id)
         const results = await AppRuntime.runPromise(
           Session.Service.use((svc) =>
             Effect.all(
@@ -438,11 +442,7 @@ export namespace KiloSessions {
           ),
         )
         const sessions = results.filter((r): r is NonNullable<typeof r> => !!r)
-        return {
-          sessions,
-          focused: focused.size > 0 ? [...focused] : undefined,
-          open: opened.size > 0 ? [...opened] : undefined,
-        }
+        return { sessions }
       }
 
       const conn = RemoteWS.connect({
@@ -515,15 +515,11 @@ export namespace KiloSessions {
       connected: remote?.conn.connected ?? false,
     }
   }
-  export function setViewedSessions(input: { focused: readonly string[]; open?: readonly string[] }) {
-    focused.clear()
-    opened.clear()
-    for (const id of input.focused) {
-      focused.add(id)
-    }
-    for (const id of input.open ?? []) {
-      opened.add(id)
-    }
+  export function setAttachedSessions(ids: readonly string[]) {
+    const next = new Set(ids)
+    if (same(next, attached)) return
+    attached.clear()
+    for (const id of next) attached.add(id)
     if (remote) void remote.conn.heartbeat().catch((err) => log.warn("heartbeat failed", { error: String(err) }))
   }
 
diff --git a/packages/opencode/src/kilo-sessions/remote-protocol.ts b/packages/opencode/src/kilo-sessions/remote-protocol.ts
index 6077e86844..d7280b9882 100644
--- a/packages/opencode/src/kilo-sessions/remote-protocol.ts
+++ b/packages/opencode/src/kilo-sessions/remote-protocol.ts
@@ -18,8 +18,6 @@ export namespace RemoteProtocol {
   export const Heartbeat = z.object({
     type: z.literal("heartbeat"),
     sessions: z.array(SessionInfo),
-    focused: z.array(z.string()).optional(),
-    open: z.array(z.string()).optional(),
     protocolVersion: z.string().optional(), // lets relay detect CLI capabilities without probing commands
   })
   export type Heartbeat = z.infer<typeof Heartbeat>
diff --git a/packages/opencode/src/kilo-sessions/remote-ws.ts b/packages/opencode/src/kilo-sessions/remote-ws.ts
index 32c6b6688e..d755ea27f0 100644
--- a/packages/opencode/src/kilo-sessions/remote-ws.ts
+++ b/packages/opencode/src/kilo-sessions/remote-ws.ts
@@ -7,7 +7,7 @@ export namespace RemoteWS {
   export type Options = {
     url: string
     getToken: () => Promise<string | undefined>
-    getSessions: () => Promise<{ sessions: SessionInfo[]; focused?: string[]; open?: string[] }>
+    getSessions: () => Promise<{ sessions: SessionInfo[] }>
     log: {
       info: (...args: any[]) => void
       error: (...args: any[]) => void
diff --git a/packages/opencode/src/kilocode/claw/client.ts b/packages/opencode/src/kilocode/claw/client.ts
index 06f63e8e33..14a9586208 100644
--- a/packages/opencode/src/kilocode/claw/client.ts
+++ b/packages/opencode/src/kilocode/claw/client.ts
@@ -18,6 +18,7 @@ import type {
   ChatToken,
   ContentBlock,
   ConversationActivityEvent,
+  ConversationLeftEvent,
   ConversationListItem,
   ConversationRenamedEvent,
   ConversationStatusEvent,
@@ -29,7 +30,7 @@ import type {
   TypingMember,
 } from "./types"
 import { KiloChatClient } from "./kilo-chat-client"
-import { EventServiceClient } from "./event-service-client"
+import { EventServiceClient } from "@/kilocode/event-service/client"
 import * as Log from "@opencode-ai/core/util/log"
 
 const log = Log.create({ service: "claw-chat" })
@@ -282,7 +283,7 @@ export async function connect(input: ConnectInput): Promise<ClawChatClient> {
     emit(conversationsListeners, conversations)
   })
 
-  events.on("conversation.left", (ctx, e) => {
+  events.on("conversation.left", (ctx, e: ConversationLeftEvent) => {
     if (ctx !== sandboxCtx) return
     conversations = conversations.filter((c) => c.conversationId !== e.conversationId)
     emit(conversationsListeners, conversations)
diff --git a/packages/opencode/src/kilocode/cli/cmd/tui/app.tsx b/packages/opencode/src/kilocode/cli/cmd/tui/app.tsx
index 46b45902e2..fefa7985a9 100644
--- a/packages/opencode/src/kilocode/cli/cmd/tui/app.tsx
+++ b/packages/opencode/src/kilocode/cli/cmd/tui/app.tsx
@@ -5,8 +5,8 @@
  * via thin integration points so the upstream diff stays minimal.
  */
 
-import { createEffect, on } from "solid-js"
-import { useKeyboard } from "@opentui/solid"
+import { createEffect, createMemo, on, onCleanup } from "solid-js"
+import { useKeyboard, useRenderer } from "@opentui/solid"
 import { TextAttributes } from "@opentui/core"
 import * as Clipboard from "@tui/util/clipboard"
 import { useBindings } from "@tui/keymap"
@@ -77,37 +77,72 @@ export function useSessionEffects(deps: {
   sync: ReturnType<typeof useSync>
 }) {
   const pty = process.env.KILO_PTY_ID
-  const state = { prev: "" }
+  const viewerId = crypto.randomUUID()
+  const renderer = useRenderer()
+  const session = createMemo(() => (deps.route.data.type === "session" ? deps.route.data.sessionID : undefined))
+  let active = true
+  const meta = { prev: "" }
+
+  function send() {
+    const id = session()
+    const ids = id ? [id] : []
+    deps.sdk.client.session.viewed({ viewer: { id: viewerId, active }, attached: ids, visible: ids }).catch(() => {})
+  }
+
+  createEffect(() => send())
+
+  const onFocus = () => {
+    active = true
+    send()
+  }
+  const onBlur = () => {
+    active = false
+    send()
+  }
+  renderer.on("focus", onFocus)
+  renderer.on("blur", onBlur)
+
+  // The server prepends `server.connected` to every SSE (re)connect; a restarted
+  // backend has an empty viewer map, so resend the snapshot immediately instead
+  // of waiting for the 60s check-in.
+  const offConnected = deps.sdk.event.on("event", (event) => {
+    if (event.payload.type === "server.connected") send()
+  })
+
+  const timer = setInterval(send, 60_000)
 
-  // Notify server which session the user is viewing
   createEffect(() => {
-    const sessionID = deps.route.data.type === "session" ? deps.route.data.sessionID : undefined
-    deps.sdk.client.session.viewed({ focused: sessionID ? [sessionID] : [] }).catch(() => {})
-
+    const sessionID = session()
     if (!pty) return
-    const session = sessionID ? deps.sync.session.get(sessionID) : undefined
-    const key = [sessionID ?? "", session?.title ?? ""].join("\n")
-    if (key === state.prev) return
-    state.prev = key
-
+    const s = sessionID ? deps.sync.session.get(sessionID) : undefined
+    const key = [sessionID ?? "", s?.title ?? ""].join("\n")
+    if (key === meta.prev) return
+    meta.prev = key
     deps.sdk.client.pty
       .update({
         ptyID: pty,
         sessionID: sessionID ?? null,
-        ...(session?.title ? { title: session.title } : {}),
+        ...(s?.title ? { title: s.title } : {}),
       })
       .catch(() => {})
   })
 
-  // Evict per-session data from store when navigating away
   createEffect(
-    on(
-      () => (deps.route.data.type === "session" ? deps.route.data.sessionID : undefined),
-      (current, prev) => {
-        if (prev && prev !== current) deps.sync.session.evict(prev)
-      },
-    ),
+    on(session, (current, prev) => {
+      if (prev && prev !== current) deps.sync.session.evict(prev)
+    }),
   )
+
+  onCleanup(() => {
+    renderer.off("focus", onFocus)
+    renderer.off("blur", onBlur)
+    offConnected()
+    clearInterval(timer)
+    active = false
+    deps.sdk.client.session
+      .viewed({ viewer: { id: viewerId, active: false }, attached: [], visible: [] })
+      .catch(() => {})
+  })
 }
 
 // ---------------------------------------------------------------------------
diff --git a/packages/opencode/src/kilocode/claw/event-service-client.ts b/packages/opencode/src/kilocode/event-service/client.ts
similarity index 84%
rename from packages/opencode/src/kilocode/claw/event-service-client.ts
rename to packages/opencode/src/kilocode/event-service/client.ts
index 5bf2b9d8fe..717b75f215 100644
--- a/packages/opencode/src/kilocode/claw/event-service-client.ts
+++ b/packages/opencode/src/kilocode/event-service/client.ts
@@ -1,9 +1,6 @@
-// kilocode_change - new file
-
 /**
- * Event Service WebSocket client for the TUI.
+ * Generic Event Service WebSocket client.
  *
- * Minimal inline port of `@kilocode/event-service` (cloud monorepo).
  * Connects via a two-step ticket flow:
  *   1. POST `/connect-ticket` with `Authorization: Bearer <JWT>` to mint a
  *      single-use ticket (30 s TTL).
@@ -11,10 +8,15 @@
  *      `kilo.events.v1`.
  *
  * Uses the global `WebSocket` constructor (Bun, Node 22+, browsers).
+ *
+ * Disconnect invalidation: every `connect()` and `disconnect()` bumps a
+ * generation counter. `connectOnce()` captures the generation at entry and,
+ * after the ticket mint resolves, refuses to construct a socket if the
+ * generation changed or the client was disposed. `disconnect()` also aborts
+ * an in-flight ticket request and the pending handshake, so a ticket response
+ * arriving after disposal can never create a socket.
  */
 
-import type { KiloChatEventMap, KiloChatEventName } from "./types"
-
 const WS_SUBPROTOCOL = "kilo.events.v1"
 const HANDSHAKE_TIMEOUT_MS = 10_000
 const PING_INTERVAL_MS = 15_000
@@ -44,12 +46,9 @@ export class HandshakeTimeoutError extends Error {
   }
 }
 
-// Close codes that signal the server rejected us for auth/policy reasons
-// and reconnecting with the same token is pointless. Everything else
-// (including 1006 "abnormal closure" from flaky networks) is transient.
 function isAuthCloseCode(code: number): boolean {
-  if (code === 1008) return true // Policy Violation
-  if (code === 4401 || code === 4403) return true // Custom auth rejection
+  if (code === 1008) return true
+  if (code === 4401 || code === 4403) return true
   return false
 }
 
@@ -59,13 +58,10 @@ export type EventServiceConfig = {
   url: string
   getToken: () => Promise<string>
   onUnauthorized?: () => void
+  onServerError?: (error: unknown) => void
+  handshakeTimeoutMs?: number
 }
 
-/**
- * The event-service base URL is configured as a WebSocket URL (`wss://…` /
- * `ws://…`) but the connect-ticket endpoint is a plain HTTP request. Strip
- * the trailing slash and swap the protocol so `fetch()` accepts the URL.
- */
 function toHttpBase(wsBase: string): string {
   const trimmed = wsBase.replace(/\/$/, "")
   if (trimmed.startsWith("wss://")) return "https://" + trimmed.slice(6)
@@ -77,16 +73,20 @@ export class EventServiceClient {
   private readonly url: string
   private readonly getToken: () => Promise<string>
   private readonly onUnauthorized: (() => void) | undefined
+  private readonly onServerError: ((error: unknown) => void) | undefined
+  private readonly handshakeTimeoutMs: number
 
   private ws: WebSocket | null = null
   private connected = false
   private destroyed = false
+  private generation = 0
   private reconnectAttempts = 0
   private hasConnectedBefore = false
   private reconnectTimer: ReturnType<typeof setTimeout> | null = null
   private pingTimer: ReturnType<typeof setInterval> | null = null
   private handshakeTimer: ReturnType<typeof setTimeout> | null = null
   private abortHandshake: ((err: Error) => void) | null = null
+  private tickets = new Set<AbortController>()
 
   private eventHandlers = new Map<string, Set<EventHandler>>()
   private activeContexts = new Set<string>()
@@ -96,9 +96,12 @@ export class EventServiceClient {
     this.url = config.url
     this.getToken = config.getToken
     this.onUnauthorized = config.onUnauthorized
+    this.onServerError = config.onServerError
+    this.handshakeTimeoutMs = config.handshakeTimeoutMs ?? HANDSHAKE_TIMEOUT_MS
   }
 
   async connect(): Promise<void> {
+    const gen = ++this.generation
     this.destroyed = false
     this.reconnectAttempts = 0
     if (this.reconnectTimer !== null) {
@@ -108,13 +111,17 @@ export class EventServiceClient {
     try {
       await this.connectOnce()
     } catch (err) {
+      if (this.destroyed || this.generation !== gen) return
       if (this.handleAuthFailure(err)) return
       if (!this.destroyed) this.scheduleReconnect()
     }
   }
 
   disconnect(): void {
+    this.generation++
     this.destroyed = true
+    for (const ctrl of this.tickets) ctrl.abort()
+    this.tickets.clear()
     if (this.reconnectTimer !== null) {
       clearTimeout(this.reconnectTimer)
       this.reconnectTimer = null
@@ -149,9 +156,9 @@ export class EventServiceClient {
     }
   }
 
-  on<N extends KiloChatEventName>(event: N, handler: (ctx: string, payload: KiloChatEventMap[N]) => void): () => void {
+  on<T = unknown>(event: string, handler: (context: string, payload: T) => void): () => void {
     const set = this.eventHandlers.get(event) ?? new Set<EventHandler>()
-    const wrapped: EventHandler = (ctx, payload) => handler(ctx, payload as KiloChatEventMap[N])
+    const wrapped: EventHandler = (ctx, payload) => handler(ctx, payload as T)
     set.add(wrapped)
     this.eventHandlers.set(event, set)
     return () => {
@@ -181,6 +188,7 @@ export class EventServiceClient {
   }
 
   private async connectOnce(): Promise<void> {
+    const gen = this.generation
     if (this.ws) {
       const old = this.ws
       this.ws = null
@@ -188,7 +196,9 @@ export class EventServiceClient {
     }
 
     const token = await this.getToken()
+    if (this.destroyed || this.generation !== gen) return
     const ticket = await this.fetchTicket(token)
+    if (this.destroyed || this.generation !== gen) return
 
     return new Promise<void>((resolve, reject) => {
       const ws = new WebSocket(`${this.url}/connect?ticket=${encodeURIComponent(ticket)}`, [WS_SUBPROTOCOL])
@@ -215,9 +225,10 @@ export class EventServiceClient {
         this.handshakeTimer = null
         if (this.ws === ws) ws.close(1000, "handshake-timeout")
         settleReject(new HandshakeTimeoutError())
-      }, HANDSHAKE_TIMEOUT_MS)
+      }, this.handshakeTimeoutMs)
 
       ws.addEventListener("open", () => {
+        if (this.ws !== ws) return
         const isReconnect = this.hasConnectedBefore
         this.connected = true
         this.hasConnectedBefore = true
@@ -231,6 +242,7 @@ export class EventServiceClient {
       })
 
       ws.addEventListener("message", (event: MessageEvent) => {
+        if (this.ws !== ws) return
         this.handleMessage(String(event.data))
       })
 
@@ -240,10 +252,6 @@ export class EventServiceClient {
         this.connected = false
         this.stopPing()
         this.clearHandshakeTimer()
-        // A handshake failure always fires `close` after `error`, so we
-        // settle here with a classification based on the close code:
-        // explicit auth/policy codes → fatal; anything else → transient
-        // and the caller (`connect`) will schedule a reconnect.
         if (!wasConnected) {
           if (isAuthCloseCode(event.code)) {
             settleReject(new WebSocketAuthError())
@@ -257,23 +265,13 @@ export class EventServiceClient {
         if (!this.destroyed) this.scheduleReconnect()
       })
 
-      ws.addEventListener("error", () => {
-        // Swallowed: the `close` event fires right after and carries the
-        // close code we need to distinguish auth failures from network
-        // blips. Settling here loses that context.
-      })
+      ws.addEventListener("error", () => {})
     })
   }
 
-  /**
-   * Mint a single-use connection ticket. The event-service issues a 30 s ticket
-   * scoped to the bearer JWT; the WebSocket upgrade then consumes it.
-   *
-   * `this.url` is the WebSocket base (`wss://…` or `ws://…`); `fetch()` only
-   * accepts `http(s)`, so we rewrite the protocol before the HTTP call.
-   */
   private async fetchTicket(token: string): Promise<string> {
     const ctrl = new AbortController()
+    this.tickets.add(ctrl)
     const timer = setTimeout(() => ctrl.abort(), TICKET_FETCH_TIMEOUT_MS)
     try {
       const res = await fetch(toHttpBase(this.url) + "/connect-ticket", {
@@ -300,6 +298,7 @@ export class EventServiceClient {
       throw new WebSocketConnectError(`Event-service ticket request failed: ${(err as Error)?.message ?? err}`, 0)
     } finally {
       clearTimeout(timer)
+      this.tickets.delete(ctrl)
     }
   }
 
@@ -335,6 +334,7 @@ export class EventServiceClient {
     }
     if (m.type === "error") {
       console.warn("[Kilo] event-service server error", m)
+      this.onServerError?.(m)
     }
   }
 
@@ -370,7 +370,10 @@ export class EventServiceClient {
     this.reconnectAttempts++
     this.reconnectTimer = setTimeout(() => {
       this.reconnectTimer = null
+      if (this.destroyed) return
+      const gen = this.generation
       this.connectOnce().catch((err) => {
+        if (this.destroyed || this.generation !== gen) return
         if (this.handleAuthFailure(err)) return
         if (!this.destroyed) this.scheduleReconnect()
       })
diff --git a/packages/opencode/src/kilocode/presence/context.ts b/packages/opencode/src/kilocode/presence/context.ts
new file mode 100644
index 0000000000..1c8e209c2f
--- /dev/null
+++ b/packages/opencode/src/kilocode/presence/context.ts
@@ -0,0 +1,34 @@
+// Presence context strings mirror the (private) cloud Event Service context
+// scheme. The cloud package is private, so the literals are duplicated here and
+// guarded by contract tests; a full drift guard lands later.
+
+export const CONTEXT_PREFIX = "/presence/"
+export const CLI_SESSION_PREFIX = "/presence/cli-session/"
+
+export type Platform = "cli" | "vscode"
+
+export function platformContext(platform: Platform): string {
+  return `${CONTEXT_PREFIX}${platform}`
+}
+
+export function cliSessionContext(sessionId: string): string {
+  return `${CLI_SESSION_PREFIX}${sessionId}`
+}
+
+// Event Service enforces a 256-char context limit.
+export const MAX_CONTEXT_LENGTH = 256
+// CLI_SESSION_PREFIX is 22 chars, so a session id must be <= 234 to keep the
+// full context within the 256-char limit.
+export const MAX_SESSION_ID_LENGTH = MAX_CONTEXT_LENGTH - CLI_SESSION_PREFIX.length
+
+// Event Service socket limit is 200 contexts.
+export const MAX_CONTEXTS = 200
+// Reserve one slot for the platform context; visible session contexts cap at 199.
+export const MAX_VISIBLE_SESSIONS = MAX_CONTEXTS - 1
+
+// Per-viewer rejection thresholds: the service rejects oversized snapshots.
+export const MAX_ATTACHED_PER_VIEWER = 1000
+export const MAX_VISIBLE_PER_VIEWER = 199
+
+// Viewer lease TTL: a viewer expires exactly 120s after its last update.
+export const VIEWER_TTL_MS = 120_000
diff --git a/packages/opencode/src/kilocode/presence/policy.ts b/packages/opencode/src/kilocode/presence/policy.ts
new file mode 100644
index 0000000000..f426ccc274
--- /dev/null
+++ b/packages/opencode/src/kilocode/presence/policy.ts
@@ -0,0 +1,151 @@
+import {
+  MAX_ATTACHED_PER_VIEWER,
+  MAX_SESSION_ID_LENGTH,
+  MAX_VISIBLE_PER_VIEWER,
+  MAX_VISIBLE_SESSIONS,
+  VIEWER_TTL_MS,
+  cliSessionContext,
+  platformContext,
+  type Platform,
+} from "./context"
+
+export type ViewerSnapshot = {
+  viewer: { id: string; active: boolean }
+  attached: readonly string[]
+  visible: readonly string[]
+}
+
+export type ViewerState = {
+  id: string
+  active: boolean
+  attached: string[]
+  visible: string[]
+  lastSeen: number
+}
+
+export type ValidationError =
+  | { kind: "missing_viewer" }
+  | { kind: "bad_viewer_id" }
+  | { kind: "attached_too_many" }
+  | { kind: "visible_too_many" }
+  | { kind: "bad_session_id"; id: string }
+
+const UUID_RE = /^[0-9a-f]{8}-[0-9a-f]{4}-[1-8][0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i
+
+function validSessionId(sid: unknown): boolean {
+  return typeof sid === "string" && sid.startsWith("ses") && sid.length <= MAX_SESSION_ID_LENGTH
+}
+
+// Deduplicate preserving first-seen order.
+export function dedupe(ids: readonly string[]): string[] {
+  const seen = new Set<string>()
+  const out: string[] = []
+  for (const id of ids) {
+    if (seen.has(id)) continue
+    seen.add(id)
+    out.push(id)
+  }
+  return out
+}
+
+type ValidationResult =
+  | { ok: true; viewer: { id: string; active: boolean }; attached: string[]; visible: string[] }
+  | { ok: false; error: ValidationError }
+
+export function validateSnapshot(input: {
+  viewer?: { id?: unknown; active?: unknown }
+  attached?: unknown
+  visible?: unknown
+}): ValidationResult {
+  const v = input.viewer
+  if (!v || typeof v !== "object") return { ok: false, error: { kind: "missing_viewer" } }
+  const id = v.id
+  if (typeof id !== "string" || !UUID_RE.test(id)) return { ok: false, error: { kind: "bad_viewer_id" } }
+
+  const rawAttached: readonly unknown[] = Array.isArray(input.attached) ? input.attached : []
+  const rawVisible: readonly unknown[] = Array.isArray(input.visible) ? input.visible : []
+
+  // Reject on raw input size first to bound dedupe work.
+  if (rawAttached.length > MAX_ATTACHED_PER_VIEWER) return { ok: false, error: { kind: "attached_too_many" } }
+  if (rawVisible.length > MAX_VISIBLE_PER_VIEWER) return { ok: false, error: { kind: "visible_too_many" } }
+
+  for (const sid of rawAttached) {
+    if (!validSessionId(sid)) {
+      return { ok: false, error: { kind: "bad_session_id", id: typeof sid === "string" ? sid : String(sid) } }
+    }
+  }
+  for (const sid of rawVisible) {
+    if (!validSessionId(sid)) {
+      return { ok: false, error: { kind: "bad_session_id", id: typeof sid === "string" ? sid : String(sid) } }
+    }
+  }
+
+  return {
+    ok: true,
+    viewer: { id, active: v.active === true },
+    attached: dedupe(rawAttached as readonly string[]),
+    visible: dedupe(rawVisible as readonly string[]),
+  }
+}
+
+// Union of every viewer's attached ids (retained regardless of active).
+export function attachedUnion(viewers: readonly ViewerState[]): string[] {
+  const all: string[] = []
+  for (const v of viewers) all.push(...v.attached)
+  return dedupe(all)
+}
+
+// Union of ACTIVE viewers' visible ids, deduped and lexicographically capped at
+// MAX_VISIBLE_SESSIONS. Returns the retained ids and how many were omitted.
+export function visibleUnion(viewers: readonly ViewerState[]): { ids: string[]; omitted: number } {
+  const all: string[] = []
+  for (const v of viewers) {
+    if (!v.active) continue
+    all.push(...v.visible)
+  }
+  const union = dedupe(all)
+  union.sort()
+  const retained = union.slice(0, MAX_VISIBLE_SESSIONS)
+  return { ids: retained, omitted: union.length - retained.length }
+}
+
+// Viewer ids expired at `now` (now >= lastSeen + VIEWER_TTL_MS).
+export function expiredViewerIds(viewers: readonly ViewerState[], now: number): string[] {
+  const out: string[] = []
+  for (const v of viewers) {
+    if (now >= v.lastSeen + VIEWER_TTL_MS) out.push(v.id)
+  }
+  return out
+}
+
+// Earliest upcoming expiry deadline strictly greater than `now`, or undefined.
+export function nextExpiryDeadline(viewers: readonly ViewerState[], now: number): number | undefined {
+  let min: number | undefined
+  for (const v of viewers) {
+    const deadline = v.lastSeen + VIEWER_TTL_MS
+    if (deadline <= now) continue
+    if (min === undefined || deadline < min) min = deadline
+  }
+  return min
+}
+
+// Reconcile desired Event Service contexts: removals first, then additions.
+export function reconcileContexts(
+  prev: ReadonlySet<string>,
+  next: ReadonlySet<string>,
+): { remove: string[]; add: string[] } {
+  const remove: string[] = []
+  const add: string[] = []
+  for (const c of prev) if (!next.has(c)) remove.push(c)
+  for (const c of next) if (!prev.has(c)) add.push(c)
+  return { remove, add }
+}
+
+// Desired Event Service context set for a platform and the capped visible ids.
+// The platform context is published only when at least one viewer is active.
+export function desiredContexts(platform: Platform, active: boolean, visibleIds: readonly string[]): Set<string> {
+  const out = new Set<string>()
+  if (active) out.add(platformContext(platform))
+  for (const id of visibleIds) out.add(cliSessionContext(id))
+  return out
+}
diff --git a/packages/opencode/src/kilocode/presence/service.ts b/packages/opencode/src/kilocode/presence/service.ts
new file mode 100644
index 0000000000..fbbfbc5c56
--- /dev/null
+++ b/packages/opencode/src/kilocode/presence/service.ts
@@ -0,0 +1,224 @@
+import { Auth } from "@/auth"
+import { EventServiceClient } from "@/kilocode/event-service/client"
+import { KILO_EVENT_SERVICE_URL } from "@kilocode/kilo-gateway"
+import * as Log from "@opencode-ai/core/util/log"
+import { Context, Effect, Layer } from "effect"
+import type { Platform } from "./context"
+import {
+  attachedUnion,
+  desiredContexts,
+  dedupe,
+  expiredViewerIds,
+  nextExpiryDeadline,
+  reconcileContexts,
+  validateSnapshot,
+  visibleUnion,
+  type ViewerSnapshot,
+  type ViewerState,
+} from "./policy"
+
+const log = Log.create({ service: "kilo-viewers" })
+
+function inferPlatform(): Platform | undefined {
+  const p = process.env.KILO_PLATFORM
+  if (p === "vscode") return "vscode"
+  if (p === "cli") return "cli"
+  if (p === undefined || p === "") return "cli"
+  return undefined
+}
+
+function extract(auth: Auth.Info | undefined): { token: string | undefined; identity: string | undefined } {
+  const envKey = process.env.KILO_API_KEY?.trim()
+  if (auth?.type === "api" && auth.key.length > 0) return { token: auth.key, identity: "api" }
+  if (auth?.type === "oauth" && auth.access.length > 0)
+    return { token: auth.access, identity: `oauth:${auth.accountId ?? "no-acct"}` }
+  if (auth?.type === "wellknown" && auth.token.length > 0) return { token: auth.token, identity: "wellknown" }
+  if (envKey) return { token: envKey, identity: "env" }
+  return { token: undefined, identity: undefined }
+}
+
+function sameArr(a: readonly string[], b: readonly string[]): boolean {
+  if (a.length !== b.length) return false
+  const set = new Set(a)
+  for (const id of b) if (!set.has(id)) return false
+  return true
+}
+
+export namespace KiloViewers {
+  export interface Interface {
+    readonly update: (snapshot: ViewerSnapshot) => Effect.Effect<void>
+    readonly invalidateAuth: () => Effect.Effect<void>
+  }
+
+  export class Service extends Context.Service<Service, Interface>()("@kilocode/KiloViewers") {}
+
+  export const layer = Layer.effect(
+    Service,
+    Effect.gen(function* () {
+      const auth = yield* Auth.Service
+      const KiloSessions = (yield* Effect.promise(() => import("@/kilo-sessions/kilo-sessions"))).KiloSessions
+
+      const platform = inferPlatform()
+      const killSwitch = process.env.KILO_DISABLE_PRESENCE === "1"
+      // Same endpoint the server envelope hands KiloClaw; KILO_EVENT_SERVICE_URL
+      // is a presence-specific override on top of the gateway's EVENT_SERVICE_URL.
+      const url = process.env.KILO_EVENT_SERVICE_URL || KILO_EVENT_SERVICE_URL
+
+      const s = {
+        viewers: new Map<string, ViewerState>(),
+        prevAttached: [] as string[],
+        prevContexts: new Set<string>(),
+        identity: undefined as string | undefined,
+        token: undefined as string | undefined,
+        client: undefined as EventServiceClient | undefined,
+        timer: null as ReturnType<typeof setTimeout> | null,
+      }
+
+      function presenceEnabled(): boolean {
+        return !killSwitch && !!url && !!platform && !!s.token
+      }
+
+      function disconnectClient() {
+        if (s.client) {
+          s.client.disconnect()
+          s.client = undefined
+        }
+        s.prevContexts = new Set()
+      }
+
+      function rebuild() {
+        log.warn("rebuilding presence connection")
+        disconnectClient()
+        apply(Date.now())
+      }
+
+      function onServerError(err: unknown) {
+        const e = err as Record<string, unknown>
+        const code = typeof e.code === "string" ? e.code : typeof e.error === "string" ? e.error : ""
+        if (code === "too_many_contexts") rebuild()
+      }
+
+      function pruneExpired(now: number) {
+        const expired = expiredViewerIds([...s.viewers.values()], now)
+        for (const id of expired) s.viewers.delete(id)
+      }
+
+      function pushAttached() {
+        const union = attachedUnion([...s.viewers.values()])
+        if (!sameArr(union, s.prevAttached)) {
+          s.prevAttached = union
+          KiloSessions.setAttachedSessions(union)
+        }
+      }
+
+      function reconcilePresence() {
+        if (!presenceEnabled()) {
+          if (s.client) disconnectClient()
+          return
+        }
+        const active = [...s.viewers.values()].some((v) => v.active)
+        const { ids, omitted } = visibleUnion([...s.viewers.values()])
+        if (omitted > 0) log.warn("omitted visible session contexts", { omitted })
+        const desired = desiredContexts(platform as Platform, active, ids)
+        if (!s.client) {
+          // Don't hold an idle socket open: connect only once there is a context
+          // to assert (inactive-only viewers keep attachment but publish nothing).
+          if (desired.size === 0) return
+          if (!s.token) return
+          s.client = new EventServiceClient({
+            url: url as string,
+            getToken: () => Promise.resolve(s.token!),
+            onUnauthorized: () => disconnectClient(),
+            onServerError,
+          })
+          s.client.subscribe([...desired])
+          s.prevContexts = desired
+          void s.client.connect().catch((err) => log.warn("presence connect failed", { error: String(err) }))
+          return
+        }
+        if (desired.size === 0) {
+          disconnectClient()
+          return
+        }
+        const { remove, add } = reconcileContexts(s.prevContexts, desired)
+        if (remove.length) s.client.unsubscribe(remove)
+        if (add.length) s.client.subscribe(add)
+        s.prevContexts = desired
+      }
+
+      function apply(now: number) {
+        pruneExpired(now)
+        pushAttached()
+        reconcilePresence()
+        rescheduleExpiry(now)
+      }
+
+      function rescheduleExpiry(now: number) {
+        if (s.timer) {
+          clearTimeout(s.timer)
+          s.timer = null
+        }
+        const deadline = nextExpiryDeadline([...s.viewers.values()], now)
+        if (deadline === undefined) return
+        const delay = Math.max(deadline - now, 0)
+        s.timer = setTimeout(() => {
+          s.timer = null
+          apply(Date.now())
+        }, delay)
+      }
+
+      const readAuth = auth.get("kilo").pipe(Effect.orElseSucceed((): Auth.Info | undefined => undefined))
+
+      const update = Effect.fn("KiloViewers.update")(function* (snapshot: ViewerSnapshot) {
+        const info = yield* readAuth
+        const { token, identity } = extract(info)
+        if (identity !== s.identity) {
+          disconnectClient()
+          s.identity = identity
+        }
+        s.token = token
+
+        const result = validateSnapshot(snapshot)
+        if (!result.ok) {
+          log.warn("rejected viewer snapshot", { error: result.error.kind })
+          return
+        }
+        s.viewers.set(result.viewer.id, {
+          id: result.viewer.id,
+          active: result.viewer.active,
+          attached: dedupe(result.attached),
+          visible: dedupe(result.visible),
+          lastSeen: Date.now(),
+        })
+        apply(Date.now())
+      })
+
+      const invalidateAuth = Effect.fn("KiloViewers.invalidateAuth")(function* () {
+        disconnectClient()
+        s.identity = undefined
+        s.token = undefined
+        const info = yield* readAuth
+        const { token, identity } = extract(info)
+        s.token = token
+        s.identity = identity
+        apply(Date.now())
+      })
+
+      yield* Effect.addFinalizer(() =>
+        Effect.sync(() => {
+          if (s.timer) {
+            clearTimeout(s.timer)
+            s.timer = null
+          }
+          disconnectClient()
+          s.viewers.clear()
+          KiloSessions.setAttachedSessions([])
+        }),
+      )
+
+      return Service.of({ update, invalidateAuth })
+    }),
+  )
+
+  export const defaultLayer = layer.pipe(Layer.provide(Auth.defaultLayer))
+}
diff --git a/packages/opencode/src/kilocode/server/httpapi/server.ts b/packages/opencode/src/kilocode/server/httpapi/server.ts
index 765c9cb640..1e23654ad1 100644
--- a/packages/opencode/src/kilocode/server/httpapi/server.ts
+++ b/packages/opencode/src/kilocode/server/httpapi/server.ts
@@ -8,6 +8,7 @@ import { fenceLayer } from "@/server/routes/instance/httpapi/middleware/fence"
 import * as AnacondaDesktop from "@/kilocode/anaconda-desktop/service"
 import { BackgroundJob } from "@/background/job"
 
+import { KiloViewers } from "@/kilocode/presence/service" // kilocode_change
 import { agentBuilderHandlers } from "./handlers/agent-builder"
 import { anacondaDesktopHandlers } from "./handlers/anaconda-desktop"
 import { backgroundProcessHandlers } from "./handlers/background-process"
@@ -64,6 +65,7 @@ export function provideListener(opts?: CorsOptions) {
     corsVaryFix,
     fenceLayer,
     cors,
+    KiloViewers.defaultLayer, // kilocode_change
     FetchHttpClient.layer,
     HttpServer.layerServices,
     Layer.succeed(CorsConfig)(opts),
diff --git a/packages/opencode/src/kilocode/server/provider-auth-lifecycle.ts b/packages/opencode/src/kilocode/server/provider-auth-lifecycle.ts
index d3961975e9..be109981b6 100644
--- a/packages/opencode/src/kilocode/server/provider-auth-lifecycle.ts
+++ b/packages/opencode/src/kilocode/server/provider-auth-lifecycle.ts
@@ -1,5 +1,6 @@
 import { InstanceStore } from "@/project/instance-store"
 import { ModelCache } from "@/provider/model-cache"
+import { KiloViewers } from "@/kilocode/presence/service" // kilocode_change
 import { Effect } from "effect"
 
 export const disposeAllInstancesAfterProviderAuthCallback = Effect.fn(
@@ -9,6 +10,13 @@ export const disposeAllInstancesAfterProviderAuthCallback = Effect.fn(
   yield* store.disposeAll()
 })
 
+// kilocode_change start - drop the old presence socket; callers invoke this for the "kilo" provider only
+export const invalidatePresence = Effect.fn("KiloServer.invalidatePresence")(function* () {
+  const viewers = yield* KiloViewers.Service
+  yield* viewers.invalidateAuth()
+})
+// kilocode_change end
+
 export const invalidateAfterProviderAuthChange = Effect.fn("KiloServer.invalidateAfterProviderAuthChange")(function* (
   providerID: string,
 ) {
diff --git a/packages/opencode/src/server/routes/instance/httpapi/groups/session.ts b/packages/opencode/src/server/routes/instance/httpapi/groups/session.ts
index ba0c742a97..02837849be 100644
--- a/packages/opencode/src/server/routes/instance/httpapi/groups/session.ts
+++ b/packages/opencode/src/server/routes/instance/httpapi/groups/session.ts
@@ -75,9 +75,16 @@ export const PermissionResponsePayload = Schema.Struct({
   response: PermissionV1.Reply,
 })
 // kilocode_change start
+const PresenceSessionId = Schema.String.check(Schema.isStartsWith("ses"), Schema.isMaxLength(234)).pipe(
+  Schema.brand("SessionID"),
+)
 export const ViewedPayload = Schema.Struct({
-  focused: Schema.optional(Schema.Array(Schema.String)),
-  open: Schema.optional(Schema.Array(Schema.String)),
+  viewer: Schema.Struct({
+    id: Schema.String.check(Schema.isUUID()),
+    active: Schema.Boolean,
+  }),
+  attached: Schema.Array(PresenceSessionId).check(Schema.isMaxLength(1000)),
+  visible: Schema.Array(PresenceSessionId).check(Schema.isMaxLength(199)),
 })
 // kilocode_change end
 
@@ -454,6 +461,7 @@ export const SessionApi = HttpApi.make("session")
           query: WorkspaceRoutingQuery,
           payload: ViewedPayload,
           success: described(Schema.Boolean, "Viewed sessions updated"),
+          error: HttpApiError.BadRequest,
         }).annotateMerge(
           OpenApi.annotations({
             identifier: "session.viewed",
diff --git a/packages/opencode/src/server/routes/instance/httpapi/handlers/control.ts b/packages/opencode/src/server/routes/instance/httpapi/handlers/control.ts
index 1146910c3e..cee0ec265f 100644
--- a/packages/opencode/src/server/routes/instance/httpapi/handlers/control.ts
+++ b/packages/opencode/src/server/routes/instance/httpapi/handlers/control.ts
@@ -1,5 +1,8 @@
 import { Auth } from "@/auth"
-import { invalidateAfterProviderAuthChange } from "@/kilocode/server/provider-auth-lifecycle" // kilocode_change
+import {
+  invalidateAfterProviderAuthChange,
+  invalidatePresence,
+} from "@/kilocode/server/provider-auth-lifecycle" // kilocode_change
 import * as Log from "@opencode-ai/core/util/log"
 import { Effect } from "effect"
 import { HttpApiBuilder } from "effect/unstable/httpapi"
@@ -16,6 +19,9 @@ export const controlHandlers = HttpApiBuilder.group(RootHttpApi, "control", (han
       payload: Auth.Info
     }) {
       yield* auth.set(ctx.params.providerID, ctx.payload).pipe(Effect.orDie)
+      // kilocode_change start - drop old presence socket before instance disposal on Kilo auth changes
+      if (ctx.params.providerID === "kilo") yield* invalidatePresence()
+      // kilocode_change end
       yield* invalidateAfterProviderAuthChange(ctx.params.providerID) // kilocode_change
       return true
     })
@@ -24,6 +30,9 @@ export const controlHandlers = HttpApiBuilder.group(RootHttpApi, "control", (han
       params: { providerID: ProviderV2.ID }
     }) {
       yield* auth.remove(ctx.params.providerID).pipe(Effect.orDie)
+      // kilocode_change start - drop old presence socket before instance disposal on Kilo auth changes
+      if (ctx.params.providerID === "kilo") yield* invalidatePresence()
+      // kilocode_change end
       yield* invalidateAfterProviderAuthChange(ctx.params.providerID) // kilocode_change
       return true
     })
diff --git a/packages/opencode/src/server/routes/instance/httpapi/handlers/provider.ts b/packages/opencode/src/server/routes/instance/httpapi/handlers/provider.ts
index e31dd095f9..28b639624e 100644
--- a/packages/opencode/src/server/routes/instance/httpapi/handlers/provider.ts
+++ b/packages/opencode/src/server/routes/instance/httpapi/handlers/provider.ts
@@ -5,7 +5,10 @@ import { Provider } from "@/provider/provider"
 
 import { mapValues, pickBy } from "remeda" // kilocode_change
 import { ModelCache } from "@/provider/model-cache" // kilocode_change
-import { disposeAllInstancesAfterProviderAuthCallback } from "@/kilocode/server/provider-auth-lifecycle" // kilocode_change
+import {
+  disposeAllInstancesAfterProviderAuthCallback,
+  invalidatePresence,
+} from "@/kilocode/server/provider-auth-lifecycle" // kilocode_change
 import { providerMetadata } from "@/kilocode/provider/metadata" // kilocode_change
 import { filterPromptTrainingModels } from "@/kilocode/provider/model-filter" // kilocode_change
 import { overlay as overlayAnacondaDesktop } from "@/kilocode/anaconda-desktop/provider" // kilocode_change
@@ -126,6 +129,9 @@ export const providerHandlers = HttpApiBuilder.group(InstanceHttpApi, "provider"
           code: ctx.payload.code,
         }),
       )
+      // kilocode_change start - drop old-user presence before instance disposal on Kilo OAuth callback
+      if (ctx.params.providerID === "kilo") yield* invalidatePresence()
+      // kilocode_change end
       yield* disposeAllInstancesAfterProviderAuthCallback() // kilocode_change
       return true
     })
diff --git a/packages/opencode/src/server/routes/instance/httpapi/handlers/session.ts b/packages/opencode/src/server/routes/instance/httpapi/handlers/session.ts
index 57c074e077..8f2c202921 100644
--- a/packages/opencode/src/server/routes/instance/httpapi/handlers/session.ts
+++ b/packages/opencode/src/server/routes/instance/httpapi/handlers/session.ts
@@ -2,6 +2,7 @@ import { Image } from "@/image/image" // kilocode_change - classify user image v
 import { KiloSessionHttpApi } from "@/kilocode/server/httpapi/session-fork" // kilocode_change
 import { BlockedError as AgentRequirementError } from "@/kilocode/agent-requirements" // kilocode_change
 import { PermissionV1 } from "@opencode-ai/core/v1/permission"
+import { KiloViewers } from "@/kilocode/presence/service" // kilocode_change
 import { Agent } from "@/agent/agent"
 import { SessionV1 } from "@opencode-ai/core/v1/session"
 import { EventV2Bridge } from "@/event-v2-bridge"
@@ -62,6 +63,7 @@ export const sessionHandlers = HttpApiBuilder.group(InstanceHttpApi, "session",
     const todoSvc = yield* Todo.Service
     const summary = yield* SessionSummary.Service
     const events = yield* EventV2Bridge.Service
+    const viewers = yield* KiloViewers.Service // kilocode_change
     const scope = yield* Scope.Scope
 
     const list = Effect.fn("SessionHttpApi.list")(function* (ctx: { query: typeof ListQuery.Type }) {
@@ -421,8 +423,7 @@ export const sessionHandlers = HttpApiBuilder.group(InstanceHttpApi, "session",
 
     // kilocode_change start
     const viewed = Effect.fn("SessionHttpApi.viewed")(function* (ctx: { payload: typeof ViewedPayload.Type }) {
-      const { KiloSessions } = yield* Effect.promise(() => import("@/kilo-sessions/kilo-sessions"))
-      KiloSessions.setViewedSessions({ focused: ctx.payload.focused ?? [], open: ctx.payload.open ?? [] })
+      yield* viewers.update(ctx.payload)
       return true
     })
     // kilocode_change end
diff --git a/packages/opencode/src/server/routes/instance/httpapi/server.ts b/packages/opencode/src/server/routes/instance/httpapi/server.ts
index 120f74a940..9e940d2bca 100644
--- a/packages/opencode/src/server/routes/instance/httpapi/server.ts
+++ b/packages/opencode/src/server/routes/instance/httpapi/server.ts
@@ -38,6 +38,7 @@ import { Provider } from "@/provider/provider"
 import { PtyTicket } from "@opencode-ai/core/pty/ticket"
 import { Question } from "@/question"
 import { Notebook } from "@/kilocode/notebook/service" // kilocode_change
+import { KiloViewers } from "@/kilocode/presence/service" // kilocode_change
 import { Session } from "@/session/session"
 import { SessionCompaction } from "@/session/compaction"
 import { LLM } from "@/session/llm"
@@ -251,6 +252,7 @@ export function createRoutes(
       PtyTicket.defaultLayer,
       Question.defaultLayer,
       Notebook.defaultLayer, // kilocode_change
+      KiloViewers.defaultLayer, // kilocode_change
       Ripgrep.defaultLayer,
       RuntimeFlags.defaultLayer,
       Session.defaultLayer,
diff --git a/packages/opencode/test/kilocode/event-service/client.test.ts b/packages/opencode/test/kilocode/event-service/client.test.ts
new file mode 100644
index 0000000000..cfaac9ae34
--- /dev/null
+++ b/packages/opencode/test/kilocode/event-service/client.test.ts
@@ -0,0 +1,345 @@
+import { afterEach, describe, expect, test } from "bun:test"
+import { EventServiceClient } from "@/kilocode/event-service/client"
+
+const OriginalWebSocket = globalThis.WebSocket
+const OriginalFetch = globalThis.fetch
+const OriginalSetTimeout = globalThis.setTimeout
+const OriginalClearTimeout = globalThis.clearTimeout
+
+type WsListener = (event: unknown) => void
+
+class FakeWebSocket {
+  static readonly OPEN = 1
+  readonly url: string
+  readonly protocols: string | string[] | undefined
+  readyState = 0
+  readonly sent: string[] = []
+  closedWith: { code?: number; reason?: string } | null = null
+  private readonly listeners = new Map<string, Set<WsListener>>()
+
+  constructor(url: string, protocols?: string | string[]) {
+    this.url = url
+    this.protocols = protocols
+    sockets.push(this)
+  }
+
+  addEventListener(type: string, listener: WsListener): void {
+    const set = this.listeners.get(type) ?? new Set<WsListener>()
+    set.add(listener)
+    this.listeners.set(type, set)
+  }
+
+  send(data: string): void {
+    this.sent.push(data)
+  }
+
+  close(code?: number, reason?: string): void {
+    if (this.readyState === 3) return
+    this.readyState = 3
+    this.closedWith = { code, reason }
+  }
+
+  emitOpen(): void {
+    this.readyState = 1
+    for (const l of this.listeners.get("open") ?? []) l({})
+  }
+
+  emitMessage(data: string): void {
+    for (const l of this.listeners.get("message") ?? []) l({ data })
+  }
+
+  emitClose(code: number, reason = ""): void {
+    if (this.readyState !== 3) this.readyState = 3
+    for (const l of this.listeners.get("close") ?? []) l({ code, reason })
+  }
+
+  emitError(): void {
+    for (const l of this.listeners.get("error") ?? []) l({})
+  }
+}
+
+const sockets: FakeWebSocket[] = []
+let client: EventServiceClient | undefined
+
+function useFakeWebSocket(): void {
+  Object.defineProperty(globalThis, "WebSocket", { value: FakeWebSocket, configurable: true, writable: true })
+}
+
+function ticketBody(ticket = "t"): Response {
+  return new Response(JSON.stringify({ ticket }), { status: 200, headers: { "content-type": "application/json" } })
+}
+
+function statusBody(status: number): Response {
+  return new Response("", { status })
+}
+
+function installFetch(handler: (url: string, init?: RequestInit) => Response | Promise<Response>): void {
+  globalThis.fetch = ((input: RequestInfo | URL, init?: RequestInit) => {
+    const url = typeof input === "string" ? input : new Request(input).url
+    return Promise.resolve(handler(url, init))
+  }) as unknown as typeof globalThis.fetch
+}
+
+function installTimers() {
+  const callbacks = new Map<number, () => void>()
+  const scheduled: { delay: number }[] = []
+  let nextId = 1
+  globalThis.setTimeout = ((cb: () => void, delay?: number) => {
+    const id = nextId++
+    callbacks.set(id, cb)
+    scheduled.push({ delay: delay ?? 0 })
+    return id
+  }) as unknown as typeof setTimeout
+  globalThis.clearTimeout = ((id?: unknown) => {
+    if (typeof id === "number") callbacks.delete(id)
+  }) as unknown as typeof clearTimeout
+  return {
+    flush() {
+      const cbs = [...callbacks.values()]
+      callbacks.clear()
+      for (const cb of cbs) cb()
+    },
+    size() {
+      return callbacks.size
+    },
+    scheduled,
+  }
+}
+
+async function drain(n = 30): Promise<void> {
+  for (let i = 0; i < n; i++) await Promise.resolve()
+}
+
+afterEach(() => {
+  client?.disconnect()
+  client = undefined
+  sockets.length = 0
+  Object.defineProperty(globalThis, "WebSocket", { value: OriginalWebSocket, configurable: true, writable: true })
+  globalThis.fetch = OriginalFetch
+  globalThis.setTimeout = OriginalSetTimeout
+  globalThis.clearTimeout = OriginalClearTimeout
+})
+
+describe("EventServiceClient transport", () => {
+  test("401 ticket response is fatal and fires onUnauthorized", async () => {
+    useFakeWebSocket()
+    installFetch(() => statusBody(401))
+    let unauthorized = false
+    client = new EventServiceClient({
+      url: "wss://events.test",
+      getToken: async () => "tok",
+      onUnauthorized: () => (unauthorized = true),
+    })
+    await client.connect()
+    expect(unauthorized).toBe(true)
+    expect(client.isConnected()).toBe(false)
+    expect(sockets.length).toBe(0)
+  })
+
+  test("403 ticket response is fatal and fires onUnauthorized", async () => {
+    useFakeWebSocket()
+    installFetch(() => statusBody(403))
+    let unauthorized = false
+    client = new EventServiceClient({
+      url: "wss://events.test",
+      getToken: async () => "tok",
+      onUnauthorized: () => (unauthorized = true),
+    })
+    await client.connect()
+    expect(unauthorized).toBe(true)
+    expect(sockets.length).toBe(0)
+  })
+
+  test("handshake timeout closes the socket with handshake-timeout and is transient", async () => {
+    useFakeWebSocket()
+    installFetch(() => ticketBody())
+    const timers = installTimers()
+    client = new EventServiceClient({
+      url: "wss://events.test",
+      getToken: async () => "tok",
+      handshakeTimeoutMs: 40,
+    })
+    void client.connect()
+    await drain()
+    expect(sockets.length).toBe(1)
+    expect(timers.scheduled.some((s) => s.delay === 40)).toBe(true)
+    timers.flush()
+    expect(sockets[0].closedWith?.code).toBe(1000)
+    expect(sockets[0].closedWith?.reason).toBe("handshake-timeout")
+    await drain()
+    expect(timers.size()).toBe(1)
+  })
+
+  test("transient close code schedules a reconnect that opens a new socket", async () => {
+    useFakeWebSocket()
+    installFetch(() => ticketBody())
+    const timers = installTimers()
+    client = new EventServiceClient({
+      url: "wss://events.test",
+      getToken: async () => "tok",
+      handshakeTimeoutMs: 5000,
+    })
+    const p = client.connect()
+    await drain()
+    expect(sockets.length).toBe(1)
+    sockets[0].emitOpen()
+    await p
+    expect(client.isConnected()).toBe(true)
+    sockets[0].emitClose(1006)
+    expect(timers.size()).toBe(1)
+    timers.flush()
+    await drain()
+    expect(sockets.length).toBe(2)
+    sockets[1].emitOpen()
+    await drain()
+    expect(client.isConnected()).toBe(true)
+  })
+
+  test("reconnect replays active contexts and fires onReconnect", async () => {
+    useFakeWebSocket()
+    installFetch(() => ticketBody())
+    const timers = installTimers()
+    client = new EventServiceClient({
+      url: "wss://events.test",
+      getToken: async () => "tok",
+      handshakeTimeoutMs: 5000,
+    })
+    let reconnectFired = false
+    client.onReconnect(() => (reconnectFired = true))
+    const p = client.connect()
+    await drain()
+    sockets[0].emitOpen()
+    await p
+    expect(reconnectFired).toBe(false)
+    client.subscribe(["ctx-1"])
+    expect(sockets[0].sent).toContain(JSON.stringify({ type: "context.subscribe", contexts: ["ctx-1"] }))
+    sockets[0].emitClose(1006)
+    timers.flush()
+    await drain()
+    expect(sockets.length).toBe(2)
+    sockets[1].emitOpen()
+    await drain()
+    expect(reconnectFired).toBe(true)
+    expect(JSON.parse(sockets[1].sent[0])).toEqual({ type: "context.subscribe", contexts: ["ctx-1"] })
+  })
+
+  test("unsubscribe sends while connected and disconnect closes the socket", async () => {
+    useFakeWebSocket()
+    installFetch(() => ticketBody())
+    client = new EventServiceClient({ url: "wss://events.test", getToken: async () => "tok" })
+    const p = client.connect()
+    await drain()
+    sockets[0].emitOpen()
+    await p
+    client.subscribe(["ctx-1"])
+    client.unsubscribe(["ctx-1"])
+    expect(sockets[0].sent).toContain(JSON.stringify({ type: "context.unsubscribe", contexts: ["ctx-1"] }))
+    client.disconnect()
+    expect(client.isConnected()).toBe(false)
+    expect(sockets[0].closedWith).not.toBeNull()
+  })
+
+  test("disposal during token lookup does not start a ticket request", async () => {
+    useFakeWebSocket()
+    let resolveToken!: (token: string) => void
+    const token = new Promise<string>((resolve) => (resolveToken = resolve))
+    let requests = 0
+    installFetch(() => {
+      requests++
+      return ticketBody()
+    })
+    client = new EventServiceClient({ url: "wss://events.test", getToken: () => token })
+
+    const pending = client.connect()
+    await drain()
+    client.disconnect()
+    resolveToken("tok")
+    await pending
+
+    expect(requests).toBe(0)
+    expect(sockets.length).toBe(0)
+  })
+
+  test("disconnect aborts ticket requests from concurrent connect attempts", async () => {
+    useFakeWebSocket()
+    installTimers()
+    const signals: AbortSignal[] = []
+    installFetch(
+      (_url, init) =>
+        new Promise<Response>((_resolve, reject) => {
+          const signal = init?.signal
+          if (!signal) return
+          signals.push(signal)
+          signal.addEventListener("abort", () => reject(new DOMException("Aborted", "AbortError")))
+        }),
+    )
+    client = new EventServiceClient({ url: "wss://events.test", getToken: async () => "tok" })
+
+    void client.connect()
+    await drain()
+    void client.connect()
+    await drain()
+    expect(signals).toHaveLength(2)
+
+    client.disconnect()
+    await drain()
+    expect(signals.every((signal) => signal.aborted)).toBe(true)
+  })
+
+  test("disposal during ticket minting never creates a socket", async () => {
+    useFakeWebSocket()
+    let resolveFetch!: (r: Response) => void
+    const fetchPromise = new Promise<Response>((r) => (resolveFetch = r))
+    installFetch(() => fetchPromise)
+    client = new EventServiceClient({ url: "wss://events.test", getToken: async () => "tok" })
+    const p = client.connect()
+    await drain()
+    expect(sockets.length).toBe(0)
+    client.disconnect()
+    resolveFetch(ticketBody())
+    await p
+    expect(sockets.length).toBe(0)
+    expect(client.isConnected()).toBe(false)
+  })
+
+  test("disposal suppresses a late unauthorized ticket response", async () => {
+    useFakeWebSocket()
+    let resolveFetch!: (r: Response) => void
+    const fetchPromise = new Promise<Response>((r) => (resolveFetch = r))
+    installFetch(() => fetchPromise)
+    let unauthorized = false
+    client = new EventServiceClient({
+      url: "wss://events.test",
+      getToken: async () => "tok",
+      onUnauthorized: () => (unauthorized = true),
+    })
+    const p = client.connect()
+    await drain()
+    client.disconnect()
+    resolveFetch(statusBody(401))
+    await p
+    expect(unauthorized).toBe(false)
+  })
+
+  test("disposal during handshake closes the socket and ignores a late open", async () => {
+    useFakeWebSocket()
+    installFetch(() => ticketBody())
+    client = new EventServiceClient({
+      url: "wss://events.test",
+      getToken: async () => "tok",
+      handshakeTimeoutMs: 5000,
+    })
+    const p = client.connect()
+    await drain()
+    expect(sockets.length).toBe(1)
+    expect(sockets[0].readyState).toBe(0)
+    client.disconnect()
+    await drain()
+    sockets[0].emitOpen()
+    await drain()
+    expect(client.isConnected()).toBe(false)
+    expect(sockets[0].closedWith).not.toBeNull()
+    expect(sockets.length).toBe(1)
+    await p
+  })
+})
diff --git a/packages/opencode/test/kilocode/presence/policy.test.ts b/packages/opencode/test/kilocode/presence/policy.test.ts
new file mode 100644
index 0000000000..b9d3a6cc2f
--- /dev/null
+++ b/packages/opencode/test/kilocode/presence/policy.test.ts
@@ -0,0 +1,211 @@
+import { describe, expect, test } from "bun:test"
+import {
+  CLI_SESSION_PREFIX,
+  MAX_CONTEXT_LENGTH,
+  MAX_SESSION_ID_LENGTH,
+  cliSessionContext,
+  platformContext,
+} from "../../../src/kilocode/presence/context"
+import {
+  attachedUnion,
+  dedupe,
+  desiredContexts,
+  expiredViewerIds,
+  nextExpiryDeadline,
+  reconcileContexts,
+  validateSnapshot,
+  visibleUnion,
+  type ViewerState,
+} from "../../../src/kilocode/presence/policy"
+
+const UUID = "00000000-0000-4000-8000-000000000000"
+
+describe("presence context builders", () => {
+  test("platformContext maps a platform to its presence context", () => {
+    expect(platformContext("cli")).toBe("/presence/cli")
+    expect(platformContext("vscode")).toBe("/presence/vscode")
+  })
+
+  test("cliSessionContext prefixes the session id", () => {
+    expect(cliSessionContext("ses_123")).toBe("/presence/cli-session/ses_123")
+  })
+
+  test("CLI_SESSION_PREFIX is 22 chars and the budget derivation holds", () => {
+    expect(CLI_SESSION_PREFIX.length).toBe(22)
+    expect(MAX_CONTEXT_LENGTH - CLI_SESSION_PREFIX.length).toBe(MAX_SESSION_ID_LENGTH)
+    expect(MAX_SESSION_ID_LENGTH).toBe(234)
+  })
+
+  test("session id budget lands exactly on the 256-char context limit", () => {
+    expect(cliSessionContext("x".repeat(234)).length).toBe(256)
+    expect(cliSessionContext("x".repeat(235)).length).toBe(257)
+  })
+})
+
+describe("dedupe", () => {
+  test("preserves first-seen order and drops duplicates", () => {
+    expect(dedupe(["a", "b", "a", "c", "b"])).toEqual(["a", "b", "c"])
+    expect(dedupe([])).toEqual([])
+    expect(dedupe(["x", "x"])).toEqual(["x"])
+  })
+})
+
+describe("validateSnapshot", () => {
+  test("accepts a well-formed snapshot and dedupes arrays", () => {
+    const r = validateSnapshot({
+      viewer: { id: UUID, active: true },
+      attached: ["ses_s1", "ses_s1", "ses_s2"],
+      visible: ["ses_v1", "ses_v1"],
+    })
+    expect(r).toEqual({ ok: true, viewer: { id: UUID, active: true }, attached: ["ses_s1", "ses_s2"], visible: ["ses_v1"] })
+  })
+
+  test("missing viewer yields missing_viewer", () => {
+    expect(validateSnapshot({})).toEqual({ ok: false, error: { kind: "missing_viewer" } })
+    expect(validateSnapshot({ viewer: undefined })).toEqual({ ok: false, error: { kind: "missing_viewer" } })
+  })
+
+  test("non-UUID viewer id yields bad_viewer_id", () => {
+    expect(validateSnapshot({ viewer: { id: "not-a-uuid" } })).toEqual({ ok: false, error: { kind: "bad_viewer_id" } })
+    expect(validateSnapshot({ viewer: { id: "" } })).toEqual({ ok: false, error: { kind: "bad_viewer_id" } })
+  })
+
+  test("UUID with an invalid variant nibble yields bad_viewer_id", () => {
+    expect(validateSnapshot({ viewer: { id: "11111111-1111-1111-1111-111111111111" } })).toEqual({
+      ok: false,
+      error: { kind: "bad_viewer_id" },
+    })
+  })
+
+  test("session id missing the ses prefix yields bad_session_id", () => {
+    expect(validateSnapshot({ viewer: { id: UUID }, attached: ["no-prefix"] })).toEqual({
+      ok: false,
+      error: { kind: "bad_session_id", id: "no-prefix" },
+    })
+  })
+
+  test("attached over the per-viewer cap yields attached_too_many", () => {
+    const attached = Array.from({ length: 1001 }, (_, i) => `ses_${i}`)
+    expect(validateSnapshot({ viewer: { id: UUID }, attached })).toEqual({
+      ok: false,
+      error: { kind: "attached_too_many" },
+    })
+  })
+
+  test("visible over the per-viewer cap yields visible_too_many", () => {
+    const visible = Array.from({ length: 200 }, (_, i) => `ses_${i}`)
+    expect(validateSnapshot({ viewer: { id: UUID }, visible })).toEqual({
+      ok: false,
+      error: { kind: "visible_too_many" },
+    })
+  })
+
+  test("oversized session id yields bad_session_id with the offending id", () => {
+    const long = "ses_" + "x".repeat(231)
+    expect(validateSnapshot({ viewer: { id: UUID }, attached: [long] })).toEqual({
+      ok: false,
+      error: { kind: "bad_session_id", id: long },
+    })
+  })
+
+  test("active is coerced strictly to a boolean", () => {
+    const t = validateSnapshot({ viewer: { id: UUID, active: true }, attached: [], visible: [] })
+    expect(t.ok && t.viewer.active).toBe(true)
+    const str = validateSnapshot({ viewer: { id: UUID, active: "true" }, attached: [], visible: [] })
+    expect(str.ok && str.viewer.active).toBe(false)
+  })
+
+  test("non-array attached and visible coerce to empty arrays", () => {
+    expect(validateSnapshot({ viewer: { id: UUID }, attached: null, visible: 42 })).toEqual({
+      ok: true,
+      viewer: { id: UUID, active: false },
+      attached: [],
+      visible: [],
+    })
+  })
+})
+
+describe("attachedUnion", () => {
+  test("unions attached across viewers including inactive ones", () => {
+    const viewers: ViewerState[] = [
+      { id: "u1", active: true, attached: ["a", "b"], visible: [], lastSeen: 0 },
+      { id: "u2", active: false, attached: ["b", "c"], visible: [], lastSeen: 0 },
+    ]
+    expect(attachedUnion(viewers)).toEqual(["a", "b", "c"])
+  })
+})
+
+describe("visibleUnion", () => {
+  test("only active viewers contribute, deduped and capped at 199", () => {
+    const ids = Array.from({ length: 201 }, (_, i) => `s${String(i).padStart(4, "0")}`)
+    const viewers: ViewerState[] = [
+      { id: "u1", active: true, attached: [], visible: ids, lastSeen: 0 },
+      { id: "u2", active: false, attached: [], visible: ["z_hidden"], lastSeen: 0 },
+    ]
+    const r = visibleUnion(viewers)
+    expect(r.ids.length).toBe(199)
+    expect(r.omitted).toBe(2)
+    expect(r.ids).not.toContain("z_hidden")
+    const sorted = [...ids].sort()
+    expect(r.ids).toEqual(sorted.slice(0, 199))
+  })
+})
+
+describe("expiredViewerIds", () => {
+  test("expires at exactly lastSeen + TTL and not one ms earlier", () => {
+    const now = 1_000_000
+    const viewers: ViewerState[] = [
+      { id: "expired", active: true, attached: [], visible: [], lastSeen: now - 120_000 },
+      { id: "alive", active: true, attached: [], visible: [], lastSeen: now - 119_999 },
+    ]
+    expect(expiredViewerIds(viewers, now)).toEqual(["expired"])
+  })
+})
+
+describe("nextExpiryDeadline", () => {
+  test("returns the earliest future deadline", () => {
+    const now = 1_000_000
+    const viewers: ViewerState[] = [
+      { id: "a", active: true, attached: [], visible: [], lastSeen: now - 50_000 },
+      { id: "b", active: true, attached: [], visible: [], lastSeen: now - 10_000 },
+    ]
+    expect(nextExpiryDeadline(viewers, now)).toBe(now + 70_000)
+  })
+
+  test("returns undefined when all viewers are expired", () => {
+    const now = 1_000_000
+    const viewers: ViewerState[] = [
+      { id: "a", active: true, attached: [], visible: [], lastSeen: now - 120_000 },
+    ]
+    expect(nextExpiryDeadline(viewers, now)).toBeUndefined()
+  })
+
+  test("returns undefined for no viewers", () => {
+    expect(nextExpiryDeadline([], 0)).toBeUndefined()
+  })
+})
+
+describe("reconcileContexts", () => {
+  test("removals are prev minus next, additions are next minus prev", () => {
+    const prev = new Set(["a", "b", "c"])
+    const next = new Set(["b", "c", "d"])
+    expect(reconcileContexts(prev, next)).toEqual({ remove: ["a"], add: ["d"] })
+  })
+})
+
+describe("desiredContexts", () => {
+  test("active includes platform context plus each visible session context", () => {
+    const ctx = desiredContexts("cli", true, ["s1", "s2"])
+    expect(ctx.size).toBe(3)
+    expect(ctx.has("/presence/cli")).toBe(true)
+    expect(ctx.has("/presence/cli-session/s1")).toBe(true)
+    expect(ctx.has("/presence/cli-session/s2")).toBe(true)
+  })
+
+  test("inactive omits platform context but keeps session contexts", () => {
+    const ctx = desiredContexts("vscode", false, ["s1"])
+    expect(ctx.size).toBe(1)
+    expect(ctx.has("/presence/vscode")).toBe(false)
+    expect(ctx.has("/presence/cli-session/s1")).toBe(true)
+  })
+})
diff --git a/packages/opencode/test/kilocode/presence/service-presence.test.ts b/packages/opencode/test/kilocode/presence/service-presence.test.ts
new file mode 100644
index 0000000000..2bd0ccfb83
--- /dev/null
+++ b/packages/opencode/test/kilocode/presence/service-presence.test.ts
@@ -0,0 +1,267 @@
+import { describe, expect, mock, setSystemTime, test } from "bun:test"
+import { Effect, Layer } from "effect"
+import { Auth } from "@/auth"
+
+// Each KiloViewers.layer construction reads these env vars (post-refactor), so
+// setting them here controls presence wiring per test.
+process.env.KILO_EVENT_SERVICE_URL = "wss://test-presence"
+process.env.KILO_PLATFORM = "cli"
+
+const attachedCalls: string[][] = []
+
+type Call = { type: "subscribe" | "unsubscribe" | "connect" | "disconnect"; contexts: string[] }
+
+// Ordering log shared across FakeClient instances, so ordering can be asserted
+// across a disconnect on one client and a connect on its replacement.
+const sequence: string[] = []
+let clientSeq = 0
+
+class FakeClient {
+  calls: Call[] = []
+  id = ++clientSeq
+  constructor() {}
+  async connect(): Promise<void> {
+    this.calls.push({ type: "connect", contexts: [] })
+    sequence.push(`connect:${this.id}`)
+  }
+  disconnect(): void {
+    this.calls.push({ type: "disconnect", contexts: [] })
+    sequence.push(`disconnect:${this.id}`)
+  }
+  subscribe(contexts: string[]): void {
+    this.calls.push({ type: "subscribe", contexts: [...contexts] })
+  }
+  unsubscribe(contexts: string[]): void {
+    this.calls.push({ type: "unsubscribe", contexts: [...contexts] })
+  }
+  onReconnect(): () => void {
+    return () => {}
+  }
+}
+
+const realSessions = await import("@/kilo-sessions/kilo-sessions")
+const realSetAttached = realSessions.KiloSessions.setAttachedSessions
+mock.module("@/kilo-sessions/kilo-sessions", () => ({
+  ...realSessions,
+  KiloSessions: {
+    ...realSessions.KiloSessions,
+    setAttachedSessions: (ids: readonly string[]) => {
+      attachedCalls.push([...ids])
+      realSetAttached(ids)
+    },
+  },
+}))
+
+let current = new FakeClient()
+mock.module("@/kilocode/event-service/client", () => ({
+  EventServiceClient: class {
+    constructor() {
+      // The service constructs one client per layer; expose it for assertions.
+      current = new FakeClient()
+    }
+    async connect() {
+      await current.connect()
+    }
+    disconnect() {
+      current.disconnect()
+    }
+    subscribe(c: string[]) {
+      current.subscribe(c)
+    }
+    unsubscribe(c: string[]) {
+      current.unsubscribe(c)
+    }
+    onReconnect() {
+      return current.onReconnect()
+    }
+  },
+}))
+
+const { KiloViewers } = await import("@/kilocode/presence/service")
+
+const authLayer = Layer.succeed(
+  Auth.Service,
+  Auth.Service.of({
+    get: () => Effect.succeed({ type: "api", key: "tok" } as unknown as Auth.Info),
+    all: () => Effect.succeed({} as never),
+    set: () => Effect.void,
+    remove: () => Effect.void,
+  }),
+)
+
+const layer = KiloViewers.layer.pipe(Layer.provide(authLayer))
+
+const uid = "11111111-1111-4111-8111-111111111111"
+
+function run(body: (viewers: {
+  update: (s: {
+    viewer: { id: string; active: boolean }
+    attached: readonly string[]
+    visible: readonly string[]
+  }) => Effect.Effect<void>
+  invalidateAuth: () => Effect.Effect<void>
+}) => Effect.Effect<void>, l: typeof layer = layer) {
+  return Effect.gen(function* () {
+    const v = yield* KiloViewers.Service
+    yield* body(v)
+  }).pipe(Effect.provide(l), Effect.runPromise)
+}
+
+function subscribeCalls(): string[][] {
+  return current.calls.filter((c) => c.type === "subscribe").map((c) => c.contexts)
+}
+
+function unsubscribeCalls(): string[][] {
+  return current.calls.filter((c) => c.type === "unsubscribe").map((c) => c.contexts)
+}
+
+describe("KiloViewers.Service presence contexts", () => {
+  test("active viewer subscribes platform plus its visible session context", async () => {
+    attachedCalls.length = 0
+    current = new FakeClient()
+    await run((v) =>
+      v.update({ viewer: { id: uid, active: true }, attached: ["ses_a"], visible: ["ses_a"] }),
+    )
+    const subs = subscribeCalls()
+    expect(subs.length).toBe(1)
+    expect(subs[0]).toContain("/presence/cli")
+    expect(subs[0]).toContain("/presence/cli-session/ses_a")
+    expect(attachedCalls).toEqual([["ses_a"], []])
+  })
+
+  test("inactive viewer opens no presence socket but keeps attachment", async () => {
+    attachedCalls.length = 0
+    current = new FakeClient()
+    await run((v) =>
+      v.update({ viewer: { id: uid, active: false }, attached: ["ses_a"], visible: ["ses_a"] }),
+    )
+    expect(subscribeCalls().length).toBe(0)
+    expect(current.calls.some((c) => c.type === "connect")).toBe(false)
+    expect(attachedCalls).toEqual([["ses_a"], []])
+  })
+
+  test("replacing the visible set unsubscribes old contexts before subscribing new ones", async () => {
+    attachedCalls.length = 0
+    current = new FakeClient()
+    const olds = Array.from({ length: 199 }, (_, i) => `ses_old_${i}`)
+    const next = Array.from({ length: 199 }, (_, i) => `ses_new_${i}`)
+    await run((v) =>
+      Effect.gen(function* () {
+        yield* v.update({ viewer: { id: uid, active: true }, attached: olds, visible: olds })
+        yield* v.update({ viewer: { id: uid, active: true }, attached: next, visible: next })
+      }),
+    )
+    const order = current.calls.filter((c) => c.type === "subscribe" || c.type === "unsubscribe")
+    const firstUnsubIdx = order.findIndex((c) => c.type === "unsubscribe")
+    const lastSubIdx = order.map((c) => c.type).lastIndexOf("subscribe")
+    expect(firstUnsubIdx).toBeGreaterThan(-1)
+    expect(lastSubIdx).toBeGreaterThan(firstUnsubIdx)
+    const unsub = unsubscribeCalls().at(-1)!
+    const sub = subscribeCalls().at(-1)!
+    expect(unsub.length).toBe(199)
+    expect(sub.length).toBe(199)
+    expect(sub.every((c) => c.startsWith("/presence/cli-session/ses_new_"))).toBe(true)
+    expect(unsub.every((c) => c.startsWith("/presence/cli-session/ses_old_"))).toBe(true)
+  })
+
+  test("kill switch blocks the presence socket but attached union still reaches KiloSessions", async () => {
+    attachedCalls.length = 0
+    current = new FakeClient()
+    const prev = process.env.KILO_DISABLE_PRESENCE
+    process.env.KILO_DISABLE_PRESENCE = "1"
+    try {
+      await run((v) =>
+        v.update({ viewer: { id: uid, active: true }, attached: ["ses_a"], visible: ["ses_a"] }),
+      )
+      expect(subscribeCalls().length).toBe(0)
+      expect(current.calls.some((c) => c.type === "connect")).toBe(false)
+      expect(attachedCalls).toEqual([["ses_a"], []])
+    } finally {
+      if (prev === undefined) delete process.env.KILO_DISABLE_PRESENCE
+      else process.env.KILO_DISABLE_PRESENCE = prev
+    }
+  })
+})
+
+const uidB = "22222222-2222-4222-8222-222222222222"
+
+describe("KiloViewers.Service viewer lifecycle", () => {
+  test("viewer expires at lastSeen + 120s", async () => {
+    attachedCalls.length = 0
+    current = new FakeClient()
+    const base = 1_700_000_000_000
+    try {
+      setSystemTime(base)
+      await run((v) =>
+        Effect.gen(function* () {
+          yield* v.update({ viewer: { id: uid, active: true }, attached: ["ses_a"], visible: ["ses_a"] })
+          setSystemTime(base + 119_999)
+          yield* v.update({ viewer: { id: uidB, active: true }, attached: ["ses_b"], visible: ["ses_b"] })
+          setSystemTime(base + 120_000)
+          yield* v.update({ viewer: { id: uidB, active: true }, attached: ["ses_b"], visible: ["ses_b"] })
+        }),
+      )
+      expect(attachedCalls.length).toBe(4)
+      // One tick before the TTL the first viewer is still present.
+      expect(attachedCalls[1]).toContain("ses_a")
+      expect(attachedCalls[1]).toContain("ses_b")
+      // At exactly lastSeen + TTL it is pruned (boundary inclusive).
+      expect(attachedCalls[2]).toEqual(["ses_b"])
+      expect(attachedCalls[3]).toEqual([])
+    } finally {
+      setSystemTime()
+    }
+  })
+
+  test("account switch disconnects the old client before connecting the new one", async () => {
+    attachedCalls.length = 0
+    sequence.length = 0
+    current = new FakeClient()
+    let authInfo = { type: "api", key: "tok1" } as unknown as Auth.Info
+    const mutableAuthLayer = Layer.succeed(
+      Auth.Service,
+      Auth.Service.of({
+        get: () => Effect.sync(() => authInfo),
+        all: () => Effect.succeed({} as never),
+        set: () => Effect.void,
+        remove: () => Effect.void,
+      }),
+    )
+    let first: FakeClient | undefined
+    let second: FakeClient | undefined
+    await run(
+      (v) =>
+        Effect.gen(function* () {
+          yield* v.update({ viewer: { id: uid, active: true }, attached: ["ses_a"], visible: ["ses_a"] })
+          first = current
+          authInfo = { type: "wellknown", key: "wk", token: "tok2" } as unknown as Auth.Info
+          yield* v.invalidateAuth()
+          second = current
+          yield* v.update({ viewer: { id: uid, active: true }, attached: ["ses_a"], visible: ["ses_a"] })
+        }),
+      KiloViewers.layer.pipe(Layer.provide(mutableAuthLayer)),
+    )
+    expect(first).toBeDefined()
+    expect(second).toBeDefined()
+    expect(second).not.toBe(first)
+    const oldConnect = sequence.indexOf(`connect:${first!.id}`)
+    const oldDisconnect = sequence.indexOf(`disconnect:${first!.id}`)
+    const newConnect = sequence.indexOf(`connect:${second!.id}`)
+    expect(oldConnect).toBeGreaterThan(-1)
+    expect(oldDisconnect).toBeGreaterThan(oldConnect)
+    expect(newConnect).toBeGreaterThan(oldDisconnect)
+  })
+
+  test("scope disposal runs the finalizer", async () => {
+    attachedCalls.length = 0
+    current = new FakeClient()
+    await run((v) =>
+      v.update({ viewer: { id: uid, active: true }, attached: ["ses_a"], visible: ["ses_a"] }),
+    )
+    const types = current.calls.map((c) => c.type)
+    expect(types).toContain("connect")
+    expect(types.at(-1)).toBe("disconnect")
+    expect(types.indexOf("disconnect")).toBeGreaterThan(types.indexOf("connect"))
+    expect(attachedCalls).toEqual([["ses_a"], []])
+  })
+})
diff --git a/packages/opencode/test/kilocode/presence/service.test.ts b/packages/opencode/test/kilocode/presence/service.test.ts
new file mode 100644
index 0000000000..02d580e33e
--- /dev/null
+++ b/packages/opencode/test/kilocode/presence/service.test.ts
@@ -0,0 +1,89 @@
+import { describe, expect, mock, test } from "bun:test"
+import { Effect, Layer } from "effect"
+import { Auth } from "@/auth"
+
+const attachedCalls: string[][] = []
+
+const realSessions = await import("@/kilo-sessions/kilo-sessions")
+const realSetAttached = realSessions.KiloSessions.setAttachedSessions
+mock.module("@/kilo-sessions/kilo-sessions", () => ({
+  ...realSessions,
+  KiloSessions: {
+    ...realSessions.KiloSessions,
+    setAttachedSessions: (ids: readonly string[]) => {
+      attachedCalls.push([...ids])
+      realSetAttached(ids)
+    },
+  },
+}))
+
+const { KiloViewers } = await import("@/kilocode/presence/service")
+
+const authLayer = Layer.succeed(
+  Auth.Service,
+  Auth.Service.of({
+    get: () => Effect.succeed(undefined),
+    all: () => Effect.succeed({} as never),
+    set: () => Effect.void,
+    remove: () => Effect.void,
+  }),
+)
+
+const layer = KiloViewers.layer.pipe(Layer.provide(authLayer))
+
+const uid = "11111111-1111-4111-8111-111111111111"
+
+function run(body: (viewers: {
+  update: (s: {
+    viewer: { id: string; active: boolean }
+    attached: readonly string[]
+    visible: readonly string[]
+  }) => Effect.Effect<void>
+  invalidateAuth: () => Effect.Effect<void>
+}) => Effect.Effect<void>) {
+  return Effect.gen(function* () {
+    const v = yield* KiloViewers.Service
+    yield* body(v)
+  }).pipe(Effect.provide(layer), Effect.runPromise)
+}
+
+describe("KiloViewers.Service", () => {
+  test("pushes the attached union to KiloSessions on change", async () => {
+    attachedCalls.length = 0
+    await run((v) => v.update({ viewer: { id: uid, active: true }, attached: ["ses_a"], visible: ["ses_a"] }))
+    expect(attachedCalls).toEqual([["ses_a"], []])
+  })
+
+  test("does not re-push an unchanged attached union", async () => {
+    attachedCalls.length = 0
+    await run((v) =>
+      Effect.gen(function* () {
+        yield* v.update({ viewer: { id: uid, active: true }, attached: ["ses_a"], visible: ["ses_a"] })
+        yield* v.update({ viewer: { id: uid, active: true }, attached: ["ses_a"], visible: ["ses_a"] })
+      }),
+    )
+    expect(attachedCalls).toEqual([["ses_a"], []])
+  })
+
+  test("unions attached sessions across viewers", async () => {
+    attachedCalls.length = 0
+    await run((v) =>
+      Effect.gen(function* () {
+        yield* v.update({ viewer: { id: uid, active: true }, attached: ["ses_a"], visible: ["ses_a"] })
+        yield* v.update({ viewer: { id: "22222222-2222-4222-8222-222222222222", active: false }, attached: ["ses_b"], visible: [] })
+      }),
+    )
+    expect(attachedCalls).toEqual([["ses_a"], ["ses_a", "ses_b"], []])
+  })
+
+  test("invalidateAuth does not throw and clears presence state", async () => {
+    attachedCalls.length = 0
+    await run((v) =>
+      Effect.gen(function* () {
+        yield* v.update({ viewer: { id: uid, active: true }, attached: ["ses_a"], visible: ["ses_a"] })
+        yield* v.invalidateAuth()
+      }),
+    )
+    expect(attachedCalls.length).toBeGreaterThanOrEqual(1)
+  })
+})
diff --git a/packages/opencode/test/kilocode/server/httpapi-exercise-scenarios.ts b/packages/opencode/test/kilocode/server/httpapi-exercise-scenarios.ts
index b772667d1d..8375ebf795 100644
--- a/packages/opencode/test/kilocode/server/httpapi-exercise-scenarios.ts
+++ b/packages/opencode/test/kilocode/server/httpapi-exercise-scenarios.ts
@@ -687,8 +687,56 @@ export const kiloScenarios: Scenario[] = [
     .status(401),
   http.protected
     .post("/session/viewed", "session.viewed")
-    .at((ctx) => ({ path: "/session/viewed", headers: ctx.headers(), body: { focused: [], open: [] } }))
+    .at((ctx) => ({
+      path: "/session/viewed",
+      headers: ctx.headers(),
+      body: {
+        viewer: { id: "11111111-1111-4111-8111-111111111111", active: true },
+        attached: [],
+        visible: [],
+      },
+    }))
     .json(200, (body) => check(body === true, "session viewed should return true")),
+  http.protected
+    .post("/session/viewed", "session.viewed")
+    .at((ctx) => ({ path: "/session/viewed", headers: ctx.headers(), body: { attached: [], visible: [] } }))
+    .status(400),
+  http.protected
+    .post("/session/viewed", "session.viewed")
+    .at((ctx) => ({
+      path: "/session/viewed",
+      headers: ctx.headers(),
+      body: {
+        viewer: { id: "not-a-uuid", active: true },
+        attached: [],
+        visible: [],
+      },
+    }))
+    .status(400),
+  http.protected
+    .post("/session/viewed", "session.viewed")
+    .at((ctx) => ({
+      path: "/session/viewed",
+      headers: ctx.headers(),
+      body: {
+        viewer: { id: "11111111-1111-4111-8111-111111111111", active: true },
+        attached: ["ses_" + "x".repeat(231)],
+        visible: [],
+      },
+    }))
+    .status(400),
+  http.protected
+    .post("/session/viewed", "session.viewed")
+    .at((ctx) => ({
+      path: "/session/viewed",
+      headers: ctx.headers(),
+      body: {
+        viewer: { id: "11111111-1111-4111-8111-111111111111", active: true },
+        attached: Array.from({ length: 1001 }, () => "ses_1"),
+        visible: [],
+      },
+    }))
+    .status(400),
   http.protected
     .post("/telemetry/capture", "telemetry.capture")
     .at((ctx) => ({
diff --git a/packages/opencode/test/kilocode/sessions/remote-protocol.test.ts b/packages/opencode/test/kilocode/sessions/remote-protocol.test.ts
index 833420debb..f2c8adfa5c 100644
--- a/packages/opencode/test/kilocode/sessions/remote-protocol.test.ts
+++ b/packages/opencode/test/kilocode/sessions/remote-protocol.test.ts
@@ -29,6 +29,16 @@ describe("RemoteProtocol", () => {
     }
   })
 
+  test("heartbeat serializes sessions only", () => {
+    const msg = { type: "heartbeat", sessions: [{ id: "ses_1", status: "idle", title: "t" }] }
+    const result = RemoteProtocol.Heartbeat.safeParse(msg)
+    expect(result.success).toBe(true)
+    if (result.success) {
+      expect(result.data).not.toHaveProperty("focused")
+      expect(result.data).not.toHaveProperty("open")
+    }
+  })
+
   test("valid event parses", () => {
     const msg = {
       type: "event",
diff --git a/packages/opencode/test/kilocode/tui-session-presence-contract.test.ts b/packages/opencode/test/kilocode/tui-session-presence-contract.test.ts
new file mode 100644
index 0000000000..0678f9696e
--- /dev/null
+++ b/packages/opencode/test/kilocode/tui-session-presence-contract.test.ts
@@ -0,0 +1,78 @@
+/**
+ * Contract test for the TUI presence snapshot in kilocode/cli/cmd/tui/app.tsx.
+ *
+ * `useSessionEffects` must run inside a SolidJS owner with the @opentui/solid
+ * renderer context, so mounting it in a unit test would require mocking the TUI
+ * framework internals. These source-contract assertions pin the load-bearing
+ * presence behaviour instead: the snapshot payload shape (route session as both
+ * attached and visible), focus/blur toggling only `viewer.active`, the 60s
+ * check-in, the backend-reconnect resend, and the cleanup path (listeners and
+ * timer removed, reconnect listener unsubscribed, final empty inactive snapshot).
+ */
+
+import { describe, expect, test } from "bun:test"
+import fs from "node:fs"
+import path from "node:path"
+
+const APP_FILE = path.resolve(import.meta.dir, "../../src/kilocode/cli/cmd/tui/app.tsx")
+
+/** The useSessionEffects function body, so assertions don't match unrelated code. */
+function effects() {
+  const content = fs.readFileSync(APP_FILE, "utf-8")
+  const start = content.indexOf("export function useSessionEffects")
+  const end = content.indexOf("export function getTerminalTitle")
+  expect(start).toBeGreaterThan(-1)
+  expect(end).toBeGreaterThan(start)
+  return content.slice(start, end)
+}
+
+/** The onCleanup block of useSessionEffects (it is the last statement of the hook). */
+function cleanup() {
+  const body = effects()
+  const start = body.indexOf("onCleanup(() => {")
+  expect(start).toBeGreaterThan(-1)
+  return body.slice(start)
+}
+
+/** Collapse whitespace so multi-line expressions match regardless of formatting. */
+function flat(source: string) {
+  return source.replace(/\s+/g, " ").replace(/\( /g, "(").replace(/ \)/g, ")").replace(/,\)/g, ")")
+}
+
+describe("TUI session presence contract", () => {
+  test("snapshot sends the route session as both attached and visible", () => {
+    const body = effects()
+    expect(body).toContain('deps.route.data.type === "session" ? deps.route.data.sessionID : undefined')
+    expect(body).toContain("const ids = id ? [id] : []")
+    expect(flat(body)).toContain(
+      "deps.sdk.client.session.viewed({ viewer: { id: viewerId, active }, attached: ids, visible: ids }).catch(() => {})",
+    )
+  })
+
+  test("focus sets active=true, blur sets active=false, both resend the snapshot", () => {
+    const body = flat(effects())
+    expect(body).toContain("const onFocus = () => { active = true send() }")
+    expect(body).toContain("const onBlur = () => { active = false send() }")
+    expect(body).toContain('renderer.on("focus", onFocus)')
+    expect(body).toContain('renderer.on("blur", onBlur)')
+  })
+
+  test("60s check-in interval exists and is cleared on cleanup", () => {
+    expect(effects()).toContain("const timer = setInterval(send, 60_000)")
+    expect(cleanup()).toContain("clearInterval(timer)")
+  })
+
+  test("server.connected resends the snapshot and is unsubscribed on cleanup", () => {
+    expect(flat(effects())).toContain(
+      'const offConnected = deps.sdk.event.on("event", (event) => { if (event.payload.type === "server.connected") send() })',
+    )
+    expect(cleanup()).toContain("offConnected()")
+  })
+
+  test("cleanup removes focus/blur listeners and sends a final inactive empty snapshot", () => {
+    const tail = cleanup()
+    expect(tail).toContain('renderer.off("focus", onFocus)')
+    expect(tail).toContain('renderer.off("blur", onBlur)')
+    expect(flat(tail)).toContain(".viewed({ viewer: { id: viewerId, active: false }, attached: [], visible: [] })")
+  })
+})
diff --git a/packages/opencode/test/server/httpapi-exercise/environment.ts b/packages/opencode/test/server/httpapi-exercise/environment.ts
index 313818f91d..4594f5f329 100644
--- a/packages/opencode/test/server/httpapi-exercise/environment.ts
+++ b/packages/opencode/test/server/httpapi-exercise/environment.ts
@@ -12,6 +12,7 @@ process.env.XDG_STATE_HOME = path.join(exerciseGlobalRoot, "state")
 process.env.XDG_CACHE_HOME = path.join(exerciseGlobalRoot, "cache")
 process.env.KILO_DISABLE_SHARE = "true"
 process.env.KILO_DISABLE_SESSION_INGEST = "true" // kilocode_change - isolate the exerciser from async Kilo session sync
+process.env.KILO_DISABLE_PRESENCE = "1" // kilocode_change - presence now has a default Event Service URL; never open real sockets from the exerciser
 export const exerciseConfigDirectory = path.join(exerciseGlobalRoot, "config", "opencode")
 export const exerciseDataDirectory = path.join(exerciseGlobalRoot, "data", "kilo") // kilocode_change
 
diff --git a/packages/sdk/js/src/v2/gen/sdk.gen.ts b/packages/sdk/js/src/v2/gen/sdk.gen.ts
index 2a06325263..086b49ae22 100644
--- a/packages/sdk/js/src/v2/gen/sdk.gen.ts
+++ b/packages/sdk/js/src/v2/gen/sdk.gen.ts
@@ -5066,8 +5066,12 @@ export class Session2 extends HeyApiClient {
     parameters?: {
       directory?: string
       workspace?: string
-      focused?: Array<string>
-      open?: Array<string>
+      viewer?: {
+        id: string
+        active: boolean
+      }
+      attached?: Array<string>
+      visible?: Array<string>
     },
     options?: Options<never, ThrowOnError>,
   ) {
@@ -5078,8 +5082,9 @@ export class Session2 extends HeyApiClient {
           args: [
             { in: "query", key: "directory" },
             { in: "query", key: "workspace" },
-            { in: "body", key: "focused" },
-            { in: "body", key: "open" },
+            { in: "body", key: "viewer" },
+            { in: "body", key: "attached" },
+            { in: "body", key: "visible" },
           ],
         },
       ],
diff --git a/packages/sdk/js/src/v2/gen/types.gen.ts b/packages/sdk/js/src/v2/gen/types.gen.ts
index 01f3b2e53e..122d5e87e8 100644
--- a/packages/sdk/js/src/v2/gen/types.gen.ts
+++ b/packages/sdk/js/src/v2/gen/types.gen.ts
@@ -9804,8 +9804,12 @@ export type PartUpdateResponse = PartUpdateResponses[keyof PartUpdateResponses]
 
 export type SessionViewedData = {
   body?: {
-    focused?: Array<string>
-    open?: Array<string>
+    viewer: {
+      id: string
+      active: boolean
+    }
+    attached: Array<string>
+    visible: Array<string>
   }
   path?: never
   query?: {
@@ -9817,9 +9821,9 @@ export type SessionViewedData = {
 
 export type SessionViewedErrors = {
   /**
-   * Bad request
+   * BadRequest | InvalidRequestError
    */
-  400: BadRequestError
+  400: EffectHttpApiErrorBadRequest | InvalidRequestError
 }
 
 export type SessionViewedError = SessionViewedErrors[keyof SessionViewedErrors]
diff --git a/packages/sdk/openapi.json b/packages/sdk/openapi.json
index 553f2acb26..f049600ebe 100644
--- a/packages/sdk/openapi.json
+++ b/packages/sdk/openapi.json
@@ -8798,11 +8798,18 @@
             }
           },
           "400": {
-            "description": "Bad request",
+            "description": "BadRequest | InvalidRequestError",
             "content": {
               "application/json": {
                 "schema": {
-                  "$ref": "#/components/schemas/BadRequestError"
+                  "anyOf": [
+                    {
+                      "$ref": "#/components/schemas/effect_HttpApiError_BadRequest"
+                    },
+                    {
+                      "$ref": "#/components/schemas/InvalidRequestError"
+                    }
+                  ]
                 }
               }
             }
@@ -8816,19 +8823,41 @@
               "schema": {
                 "type": "object",
                 "properties": {
-                  "focused": {
-                    "type": "array",
-                    "items": {
-                      "type": "string"
-                    }
+                  "viewer": {
+                    "type": "object",
+                    "properties": {
+                      "id": {
+                        "type": "string",
+                        "pattern": "^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000)$",
+                        "format": "uuid"
+                      },
+                      "active": {
+                        "type": "boolean"
+                      }
+                    },
+                    "required": ["id", "active"],
+                    "additionalProperties": false
                   },
-                  "open": {
+                  "attached": {
                     "type": "array",
                     "items": {
-                      "type": "string"
-                    }
+                      "type": "string",
+                      "pattern": "^ses",
+                      "maxLength": 234
+                    },
+                    "maxItems": 1000
+                  },
+                  "visible": {
+                    "type": "array",
+                    "items": {
+                      "type": "string",
+                      "pattern": "^ses",
+                      "maxLength": 234
+                    },
+                    "maxItems": 199
                   }
                 },
+                "required": ["viewer", "attached", "visible"],
                 "additionalProperties": false
               }
             }