diff --git a/packages/opencode/src/cli/cmd/tui/app.tsx b/packages/opencode/src/cli/cmd/tui/app.tsx
index a0236bd4569..2fdc41b3934 100644
--- a/packages/opencode/src/cli/cmd/tui/app.tsx
+++ b/packages/opencode/src/cli/cmd/tui/app.tsx
@@ -268,6 +268,17 @@ function App() {
   })
   // kilocode_change end
 
+  // kilocode_change start — evict per-session data from store when navigating away
+  createEffect(
+    on(
+      () => (route.data.type === "session" ? route.data.sessionID : undefined),
+      (current, prev) => {
+        if (prev && prev !== current) sync.session.evict(prev)
+      },
+    ),
+  )
+  // kilocode_change end
+
   // Update terminal window title based on current route and session
   createEffect(() => {
     if (!terminalTitleEnabled() || Flag.KILO_DISABLE_TERMINAL_TITLE) return
diff --git a/packages/opencode/src/cli/cmd/tui/context/sync.tsx b/packages/opencode/src/cli/cmd/tui/context/sync.tsx
index 7d0d8f62ab5..e7049fcbe4e 100644
--- a/packages/opencode/src/cli/cmd/tui/context/sync.tsx
+++ b/packages/opencode/src/cli/cmd/tui/context/sync.tsx
@@ -53,7 +53,7 @@ export const { use: useSync, provider: SyncProvider } = createSimpleContext({
         [sessionID: string]: SessionStatus
       }
       session_diff: {
-        [sessionID: string]: Snapshot.FileDiff[]
+        [sessionID: string]: Omit<Snapshot.FileDiff, "before" | "after">[] // kilocode_change
       }
       todo: {
         [sessionID: string]: Todo[]
@@ -107,12 +107,42 @@ export const { use: useSync, provider: SyncProvider } = createSimpleContext({
 
     const sdk = useSDK()
 
+    const fullSyncedSessions = new Set<string>() // kilocode_change
+
     async function syncWorkspaces() {
       const result = await sdk.client.experimental.workspace.list().catch(() => undefined)
       if (!result?.data) return
       setStore("workspaceList", reconcile(result.data))
     }
 
+    // kilocode_change start
+    function evict(sessionID: string) {
+      // Collect child session IDs so we can evict them too.
+      const children = store.session.filter((s) => s.parentID === sessionID).map((s) => s.id)
+      setStore(
+        produce((draft) => {
+          const messages = draft.message[sessionID]
+          if (messages) {
+            for (const msg of messages) delete draft.part[msg.id]
+          }
+          delete draft.message[sessionID]
+          delete draft.session_diff[sessionID]
+          delete draft.session_status[sessionID]
+          delete draft.todo[sessionID]
+        }),
+      )
+      fullSyncedSessions.delete(sessionID)
+      for (const child of children) evict(child)
+    }
+
+    // Strip summary.diffs from user messages — the TUI never reads them
+    // and they can carry multi-MB before/after file content strings.
+    function strip(msg: Message): Message {
+      if (msg.role !== "user" || !msg.summary?.diffs) return msg
+      return { ...msg, summary: { ...msg.summary, diffs: [] } } as Message
+    }
+    // kilocode_change end
+
     sdk.event.listen((e) => {
       const event = e.details
       switch (event.type) {
@@ -199,21 +229,29 @@ export const { use: useSync, provider: SyncProvider } = createSimpleContext({
           break
 
         case "session.diff":
-          setStore("session_diff", event.properties.sessionID, event.properties.diff)
+          setStore(
+            "session_diff",
+            event.properties.sessionID,
+            event.properties.diff.map(({ before: _, after: __, ...rest }) => rest),
+          )
           break
 
+        // kilocode_change start
         case "session.deleted": {
-          const result = Binary.search(store.session, event.properties.info.id, (s) => s.id)
-          if (result.found) {
+          const sid = event.properties.info.id
+          const match = Binary.search(store.session, sid, (s) => s.id)
+          if (match.found) {
             setStore(
               "session",
               produce((draft) => {
-                draft.splice(result.index, 1)
+                draft.splice(match.index, 1)
               }),
             )
           }
+          evict(sid)
           break
         }
+        // kilocode_change end
         case "session.updated": {
           const result = Binary.search(store.session, event.properties.info.id, (s) => s.id)
           if (result.found) {
@@ -234,31 +272,33 @@ export const { use: useSync, provider: SyncProvider } = createSimpleContext({
           break
         }
 
+        // kilocode_change start
         case "message.updated": {
-          const messages = store.message[event.properties.info.sessionID]
+          const info = strip(event.properties.info)
+          const messages = store.message[info.sessionID]
           if (!messages) {
-            setStore("message", event.properties.info.sessionID, [event.properties.info])
+            setStore("message", info.sessionID, [info])
             break
           }
-          const result = Binary.search(messages, event.properties.info.id, (m) => m.id)
+          const result = Binary.search(messages, info.id, (m) => m.id)
           if (result.found) {
-            setStore("message", event.properties.info.sessionID, result.index, reconcile(event.properties.info))
+            setStore("message", info.sessionID, result.index, reconcile(info))
             break
           }
           setStore(
             "message",
-            event.properties.info.sessionID,
+            info.sessionID,
             produce((draft) => {
-              draft.splice(result.index, 0, event.properties.info)
+              draft.splice(result.index, 0, info)
             }),
           )
-          const updated = store.message[event.properties.info.sessionID]
+          const updated = store.message[info.sessionID]
           if (updated.length > 100) {
             const oldest = updated[0]
             batch(() => {
               setStore(
                 "message",
-                event.properties.info.sessionID,
+                info.sessionID,
                 produce((draft) => {
                   draft.shift()
                 }),
@@ -273,6 +313,7 @@ export const { use: useSync, provider: SyncProvider } = createSimpleContext({
           }
           break
         }
+        // kilocode_change end
         case "message.removed": {
           const messages = store.message[event.properties.sessionID]
           const result = Binary.search(messages, event.properties.messageID, (m) => m.id)
@@ -441,7 +482,6 @@ export const { use: useSync, provider: SyncProvider } = createSimpleContext({
       bootstrap()
     })
 
-    const fullSyncedSessions = new Set<string>()
     const result = {
       data: store,
       set: setStore,
@@ -481,15 +521,16 @@ export const { use: useSync, provider: SyncProvider } = createSimpleContext({
               if (match.found) draft.session[match.index] = session.data!
               if (!match.found) draft.session.splice(match.index, 0, session.data!)
               draft.todo[sessionID] = todo.data ?? []
-              draft.message[sessionID] = messages.data!.map((x) => x.info)
+              draft.message[sessionID] = messages.data!.map((x) => strip(x.info)) // kilocode_change
               for (const message of messages.data!) {
                 draft.part[message.info.id] = message.parts
               }
-              draft.session_diff[sessionID] = diff.data ?? []
+              draft.session_diff[sessionID] = (diff.data ?? []).map(({ before: _, after: __, ...rest }) => rest)
             }),
           )
           fullSyncedSessions.add(sessionID)
         },
+        evict, // kilocode_change
       },
       workspace: {
         get(workspaceID: string) {
diff --git a/packages/opencode/src/config/config.ts b/packages/opencode/src/config/config.ts
index 61479758974..eff231452e0 100644
--- a/packages/opencode/src/config/config.ts
+++ b/packages/opencode/src/config/config.ts
@@ -1342,16 +1342,15 @@ export namespace Config {
     const files = GLOBAL_CONFIG_FILES.map((file) => path.join(Global.Path.config, file))
     // also check legacy TOML config — its presence means existing user
     const legacy = path.join(Global.Path.config, "config")
-    const existing: string[] = []
-    for (const file of files) {
-      if (existsSync(file)) existing.push(file)
-    }
+    const existing = files.filter((file) => existsSync(file))
     const hasLegacy = existsSync(legacy)
     // no global config → new user, they'll get the new bash:ask default
     if (existing.length === 0 && !hasLegacy) return
     // check if any config file already has an explicit bash permission
     for (const file of existing) {
-      const text = await Bun.file(file).text()
+      const text = await Bun.file(file)
+        .text()
+        .catch(() => "")
       const data = parseJsonc(text) ?? {}
       if (data.permission?.bash) return
     }
@@ -1372,11 +1371,12 @@ export namespace Config {
         formattingOptions: { insertSpaces: true, tabSize: 2 },
       })
       await Bun.write(target, applyEdits(text, edits))
-    } else {
-      const data = parseJsonc(text) ?? {}
-      const merged = { ...data, permission: { ...data.permission, bash: "allow" } }
-      await Bun.write(target, JSON.stringify(merged, null, 2))
+      log.info("migrated bash permission to allow for existing user", { path: target })
+      return
     }
+    const data = parseJsonc(text) ?? {}
+    const merged = { ...data, permission: { ...data.permission, bash: "allow" } }
+    await Bun.write(target, JSON.stringify(merged, null, 2))
     log.info("migrated bash permission to allow for existing user", { path: target })
   }
   // kilocode_change end
diff --git a/packages/opencode/src/kilocode/plan-followup.ts b/packages/opencode/src/kilocode/plan-followup.ts
index cc6408b6655..caf2df67db3 100644
--- a/packages/opencode/src/kilocode/plan-followup.ts
+++ b/packages/opencode/src/kilocode/plan-followup.ts
@@ -12,7 +12,6 @@ import { LLM } from "@/session/llm"
 import { MessageV2 } from "@/session/message-v2"
 import { Todo } from "@/session/todo"
 import { Log } from "@/util/log"
-import fs from "fs/promises"
 import path from "path"
 
 function toText(item: MessageV2.WithParts): string {
@@ -115,20 +114,20 @@ export namespace PlanFollowup {
   export const ANSWER_NEW_SESSION = "Start new session"
   export const ANSWER_CONTINUE = "Continue here"
 
-  function resolveVariant(input: { value: string | undefined; model: Provider.Model | undefined }) {
-    if (!input.value) return undefined
-    if (!input.model?.variants?.[input.value]) return undefined
-    return input.value
+  function resolveVariant(value: string | undefined, model: Provider.Model | undefined) {
+    if (!value) return undefined
+    if (!model?.variants?.[value]) return undefined
+    return value
   }
 
   async function resolveCodeModel(input: Pick<MessageV2.User, "model" | "variant">) {
     const state =
       Flag.KILO_CLIENT === "cli"
-        ? await fs
-            .readFile(path.join(Global.Path.state, "model.json"), "utf-8")
+        ? await Bun.file(path.join(Global.Path.state, "model.json"))
+            .text()
             .then(
-              (item) =>
-                JSON.parse(item) as {
+              (raw) =>
+                JSON.parse(raw) as {
                   model?: Record<string, MessageV2.User["model"]>
                   variant?: Record<string, string | undefined>
                 },
@@ -142,10 +141,7 @@ export namespace PlanFollowup {
         const key = `${saved.providerID}/${saved.modelID}`
         return {
           model: saved,
-          variant: resolveVariant({
-            value: state?.variant?.[key],
-            model: full,
-          }),
+          variant: resolveVariant(state?.variant?.[key], full),
         }
       }
     }
@@ -156,12 +152,7 @@ export namespace PlanFollowup {
       if (full) {
         return {
           model: agent.model,
-          variant: agent.variant
-            ? resolveVariant({
-                value: agent.variant,
-                model: full,
-              })
-            : undefined,
+          variant: resolveVariant(agent.variant, full),
         }
       }
     }
diff --git a/packages/opencode/src/session/summary.ts b/packages/opencode/src/session/summary.ts
index f724067f665..288e5f22c2b 100644
--- a/packages/opencode/src/session/summary.ts
+++ b/packages/opencode/src/session/summary.ts
@@ -121,16 +121,23 @@ export namespace SessionSummary {
     }),
     async (input) => {
       const diffs = await Storage.read<Snapshot.FileDiff[]>(["session_diff", input.sessionID]).catch(() => [])
+      // kilocode_change start — scrub oversized diffs from stored session_diff
       const next = diffs.map((item) => {
         const file = unquoteGitPath(item.file)
-        if (file === item.file) return item
+        const oversized =
+          Buffer.byteLength(item.before) > Snapshot.MAX_DIFF_SIZE ||
+          Buffer.byteLength(item.after) > Snapshot.MAX_DIFF_SIZE
+        if (file === item.file && !oversized) return item
         return {
           ...item,
           file,
+          before: oversized ? "" : item.before,
+          after: oversized ? "" : item.after,
         }
       })
-      const changed = next.some((item, i) => item.file !== diffs[i]?.file)
+      const changed = next.some((item, i) => item !== diffs[i])
       if (changed) Storage.write(["session_diff", input.sessionID], next).catch(() => {})
+      // kilocode_change end
       return next
     },
   )
diff --git a/packages/opencode/src/snapshot/index.ts b/packages/opencode/src/snapshot/index.ts
index 9aade734eee..f2a70db9115 100644
--- a/packages/opencode/src/snapshot/index.ts
+++ b/packages/opencode/src/snapshot/index.ts
@@ -14,6 +14,7 @@ export namespace Snapshot {
   const log = Log.create({ service: "snapshot" })
   const hour = 60 * 60 * 1000
   const prune = "7.days"
+  export const MAX_DIFF_SIZE = 256 * 1024 // kilocode_change
 
   export function init() {
     Scheduler.register({
@@ -34,10 +35,11 @@ export namespace Snapshot {
       .then(() => true)
       .catch(() => false)
     if (!exists) return
-    const result = await $`git -c core.autocrlf=false -c core.longpaths=true -c core.symlinks=true --git-dir ${git} --work-tree ${Instance.worktree} gc --prune=${prune}`
-      .quiet()
-      .cwd(Instance.directory)
-      .nothrow()
+    const result =
+      await $`git -c core.autocrlf=false -c core.longpaths=true -c core.symlinks=true --git-dir ${git} --work-tree ${Instance.worktree} gc --prune=${prune}`
+        .quiet()
+        .cwd(Instance.directory)
+        .nothrow()
     if (result.exitCode !== 0) {
       log.warn("cleanup failed", {
         exitCode: result.exitCode,
@@ -228,13 +230,22 @@ export namespace Snapshot {
       if (!line) continue
       const [additions, deletions, file] = line.split("\t")
       const isBinaryFile = additions === "-" && deletions === "-"
-      const before = isBinaryFile
+      // kilocode_change start
+      const oversized =
+        !isBinaryFile &&
+        ((parseInt(await $`git --git-dir ${git} cat-file -s ${from}:${file}`.quiet().nothrow().text()) || 0) >
+          MAX_DIFF_SIZE ||
+          (parseInt(await $`git --git-dir ${git} cat-file -s ${to}:${file}`.quiet().nothrow().text()) || 0) >
+            MAX_DIFF_SIZE)
+      const skip = isBinaryFile || oversized
+      // kilocode_change end
+      const before = skip
         ? ""
         : await $`git -c core.autocrlf=false -c core.longpaths=true -c core.symlinks=true --git-dir ${git} --work-tree ${Instance.worktree} show ${from}:${file}`
             .quiet()
             .nothrow()
             .text()
-      const after = isBinaryFile
+      const after = skip
         ? ""
         : await $`git -c core.autocrlf=false -c core.longpaths=true -c core.symlinks=true --git-dir ${git} --work-tree ${Instance.worktree} show ${to}:${file}`
             .quiet()
diff --git a/packages/opencode/src/tool/task.ts b/packages/opencode/src/tool/task.ts
index a76eb9f756b..7b7eafdcb84 100644
--- a/packages/opencode/src/tool/task.ts
+++ b/packages/opencode/src/tool/task.ts
@@ -61,7 +61,7 @@ export const TaskTool = Tool.define("task", async (ctx) => {
       const agent = await Agent.get(params.subagent_type)
       if (!agent) throw new Error(`Unknown agent type: ${params.subagent_type} is not a valid agent type`)
 
-      const allowsTask = agent.permission.some((rule) => rule.permission === "task" && rule.action === "allow")
+      const allowsTask = agent.permission.some((rule) => rule.permission === "task" && rule.action === "allow") // kilocode_change
 
       const session = await iife(async () => {
         if (params.task_id) {