diff --git a/packages/opencode/src/kilocode/project-id.ts b/packages/opencode/src/kilocode/project-id.ts
index 02d016d9fd..d0dc68b949 100644
--- a/packages/opencode/src/kilocode/project-id.ts
+++ b/packages/opencode/src/kilocode/project-id.ts
@@ -1,6 +1,6 @@
-import { Context, Effect, Layer } from "effect"
+import { Cache, Context, Effect, Layer } from "effect"
 import { Instance } from "@/kilocode/instance"
-import { InstanceState } from "@/effect/instance-state"
+import { registerDisposer } from "@/effect/instance-registry"
 import { makeRuntime } from "@/effect/run-service"
 import path from "path"
 import { $ } from "bun"
@@ -83,9 +83,7 @@ async function getProjectIdFromGit(directory: string): Promise<string | undefine
  * Resolve project ID with priority: .kilo/config.json -> .kilocode/config.json -> git origin URL
  * @returns Normalized project ID or undefined
  */
-async function resolveProjectId(): Promise<string | undefined> {
-  const dir = Instance.directory
-
+async function resolveProjectId(dir: string): Promise<string | undefined> {
   // Priority 1: .kilo/config.json (falls back to .kilocode/config.json)
   const id = await getProjectIdFromConfig(dir)
   if (id) return id
@@ -104,13 +102,15 @@ export namespace KiloProjectID {
   export const layer = Layer.effect(
     Service,
     Effect.gen(function* () {
-      const state = yield* InstanceState.make(
-        Effect.fn("KiloProjectID.state")(function* () {
-          return { id: yield* Effect.promise(() => resolveProjectId()) }
-        }),
-      )
+      const cache = yield* Cache.make<string, string | undefined>({
+        capacity: Number.POSITIVE_INFINITY,
+        lookup: (directory) => Effect.promise(() => resolveProjectId(directory)),
+      })
+      const off = registerDisposer((directory) => Effect.runPromise(Cache.invalidate(cache, directory)))
+      yield* Effect.addFinalizer(() => Effect.sync(off))
+
       return Service.of({
-        get: () => InstanceState.use(state, (s) => s.id),
+        get: () => Cache.get(cache, Instance.directory),
       })
     }),
   )
diff --git a/packages/opencode/test/kilocode/project-id.test.ts b/packages/opencode/test/kilocode/project-id.test.ts
index d93dc7a85d..5d59b7d242 100644
--- a/packages/opencode/test/kilocode/project-id.test.ts
+++ b/packages/opencode/test/kilocode/project-id.test.ts
@@ -2,8 +2,9 @@ import { test, expect, describe } from "bun:test"
 import { tmpdir } from "../fixture/fixture"
 import path from "path"
 import fs from "fs/promises"
-import { provideTestInstance } from "../fixture/fixture"
+import { provideTestInstance, withTestInstance } from "../fixture/fixture"
 import { getKiloProjectId } from "../../src/kilocode/project-id"
+import { disposeInstance } from "../../src/effect/instance-registry"
 
 describe("project-id", () => {
   describe("normalization", () => {
@@ -365,26 +366,49 @@ describe("project-id", () => {
   })
 
   describe("caching", () => {
-    test("caches project ID per Instance", async () => {
-      await using tmp = await tmpdir({
-        git: true,
+    test("keeps project IDs isolated across active project contexts", async () => {
+      await using first = await tmpdir({
         init: async (dir) => {
-          await Bun.$`git remote add origin https://github.com/Kilo-Org/handbook.git`.cwd(dir).quiet()
+          await fs.mkdir(path.join(dir, ".kilo"), { recursive: true })
+          await Bun.write(path.join(dir, ".kilo", "config.json"), JSON.stringify({ project: { id: "first" } }))
+        },
+      })
+      await using second = await tmpdir({
+        init: async (dir) => {
+          await fs.mkdir(path.join(dir, ".kilo"), { recursive: true })
+          await Bun.write(path.join(dir, ".kilo", "config.json"), JSON.stringify({ project: { id: "second" } }))
         },
       })
 
-      const id1 = await provideTestInstance({
-        directory: tmp.path,
-        fn: () => getKiloProjectId(),
+      const ids = await Promise.all([
+        withTestInstance({ directory: first.path, fn: () => getKiloProjectId() }),
+        withTestInstance({ directory: second.path, fn: () => getKiloProjectId() }),
+      ])
+
+      expect(ids).toEqual(["first", "second"])
+    })
+
+    test("invalidates the cached project ID when the instance is disposed", async () => {
+      await using tmp = await tmpdir({
+        init: async (dir) => {
+          await fs.mkdir(path.join(dir, ".kilo"), { recursive: true })
+          await Bun.write(path.join(dir, ".kilo", "config.json"), JSON.stringify({ project: { id: "first" } }))
+        },
       })
 
-      const id2 = await provideTestInstance({
+      const ids = await provideTestInstance({
         directory: tmp.path,
-        fn: () => getKiloProjectId(),
+        fn: async (ctx) => {
+          const first = await getKiloProjectId()
+          await Bun.write(path.join(tmp.path, ".kilo", "config.json"), JSON.stringify({ project: { id: "second" } }))
+          const cached = await getKiloProjectId()
+          await disposeInstance(ctx.directory)
+          const refreshed = await getKiloProjectId()
+          return { first, cached, refreshed }
+        },
       })
 
-      expect(id1).toBe(id2)
-      expect(id1).toBe("handbook")
+      expect(ids).toEqual({ first: "first", cached: "first", refreshed: "second" })
     })
   })
 
diff --git a/script/architecture-allowlist.json b/script/architecture-allowlist.json
index 9ff61dc3bd..024a5c6a04 100644
--- a/script/architecture-allowlist.json
+++ b/script/architecture-allowlist.json
@@ -11,7 +11,6 @@
         "packages/opencode/src/kilocode/background-process/index.ts": { "count": 1, "owner": "process-runtime", "reason": "Directory-keyed background process registry" },
         "packages/opencode/src/kilocode/interactive-terminal/index.ts": { "count": 1, "owner": "terminal-runtime", "reason": "Interactive terminal manager state" },
         "packages/opencode/src/kilocode/notebook/service.ts": { "count": 1, "owner": "notebook-runtime", "reason": "Notebook cell execution service state" },
-        "packages/opencode/src/kilocode/project-id.ts": { "count": 1, "owner": "project-runtime", "reason": "Cached project identifier resolution" },
         "packages/opencode/src/kilocode/watcher.ts": { "count": 1, "owner": "watcher-runtime", "reason": "Eager location watcher subscription" }
       }
     },