diff --git a/.changeset/fallback-state-directory.md b/.changeset/fallback-state-directory.md
new file mode 100644
index 00000000000..5d3b95c9f9d
--- /dev/null
+++ b/.changeset/fallback-state-directory.md
@@ -0,0 +1,5 @@
+---
+"@kilocode/cli": patch
+---
+
+Start Kilo with a persistent fallback when the default runtime state directory is not writable.
diff --git a/packages/core/src/global.ts b/packages/core/src/global.ts
index ffc199317b1..10861364ab4 100644
--- a/packages/core/src/global.ts
+++ b/packages/core/src/global.ts
@@ -5,7 +5,7 @@ import os from "os"
 import { Context, Effect, Layer } from "effect"
 import { Flock } from "./util/flock"
 import { markNoIndex } from "./kilocode/spotlight" // kilocode_change
-import { ensureRealDir } from "./kilocode/global" // kilocode_change
+import { ensureRealDir, resolveState } from "./kilocode/global" // kilocode_change
 import { Flag } from "./flag/flag"
 import { makeGlobalNode } from "./effect/app-node"
 
@@ -22,7 +22,8 @@ const clean = (p: string | undefined) => p?.replace(/[\r\n]+/g, "")
 const data = path.join(clean(xdgData)!, app)
 const cache = path.join(clean(xdgCache)!, app)
 const config = path.join(clean(xdgConfig)!, app)
-const state = path.join(clean(xdgState)!, app)
+const preferred = path.join(clean(xdgState)!, app)
+const state = await resolveState(preferred, process.env.XDG_STATE_HOME ? undefined : path.join(data, "state"))
 // kilocode_change end
 const tmp = path.join(os.tmpdir(), app)
 
@@ -47,7 +48,6 @@ Flock.setGlobal({ state })
 await Promise.all([
   ensureRealDir(Path.data), // kilocode_change
   ensureRealDir(Path.config), // kilocode_change
-  ensureRealDir(Path.state), // kilocode_change
   ensureRealDir(Path.tmp), // kilocode_change
   ensureRealDir(Path.log), // kilocode_change
   ensureRealDir(Path.bin), // kilocode_change
diff --git a/packages/core/src/kilocode/global.ts b/packages/core/src/kilocode/global.ts
index b57d06f7ae9..a98d815896d 100644
--- a/packages/core/src/kilocode/global.ts
+++ b/packages/core/src/kilocode/global.ts
@@ -1,4 +1,6 @@
 import fs from "fs/promises"
+import path from "path"
+import { randomUUID } from "crypto"
 
 /**
  * Like `fs.mkdir({ recursive: true })` but also repairs broken symlinks and
@@ -21,3 +23,50 @@ export async function ensureRealDir(p: string) {
     await fs.mkdir(p, { recursive: true })
   }
 }
+
+async function writable(p: string) {
+  const probe = path.join(p, `.kilo-write-${process.pid}-${randomUUID()}`)
+  await fs.writeFile(probe, "", { flag: "wx", mode: 0o600 })
+  await fs.unlink(probe)
+}
+
+async function ready(p: string) {
+  await ensureRealDir(p)
+  await writable(p)
+}
+
+export async function resolveState(p: string, fallback?: string) {
+  const sticky =
+    fallback === undefined
+      ? false
+      : await fs.stat(fallback).then(
+          (stat) =>
+            stat.isDirectory() &&
+            writable(fallback).then(
+              () => true,
+              () => false,
+            ),
+          () => false,
+        )
+  if (sticky && fallback !== undefined) return fallback
+
+  const err = await ready(p).then(
+    () => undefined,
+    (err: unknown) => err,
+  )
+  if (err === undefined) return p
+  if (fallback === undefined) throw err
+
+  const failed = await ready(fallback).then(
+    () => undefined,
+    (err: unknown) => err,
+  )
+  if (failed !== undefined) {
+    throw new AggregateError([err, failed], `Cannot use state directory "${p}" or fallback "${fallback}"`)
+  }
+
+  const msg = err instanceof Error ? err.message : "Unknown error"
+  // Logging is not initialized until Global.Path.log exists.
+  console.warn(`[kilo] Cannot use state directory "${p}"; using "${fallback}" instead: ${msg}`)
+  return fallback
+}
diff --git a/packages/core/test/kilocode/global.test.ts b/packages/core/test/kilocode/global.test.ts
new file mode 100644
index 00000000000..5575e869f1e
--- /dev/null
+++ b/packages/core/test/kilocode/global.test.ts
@@ -0,0 +1,109 @@
+import fs from "fs/promises"
+import path from "path"
+import { describe, expect, test } from "bun:test"
+import { resolveState } from "@opencode-ai/core/kilocode/global"
+import { tmpdir } from "../fixture/tmpdir"
+
+const skip = process.platform === "win32" || process.getuid?.() === 0
+
+describe("global state directory", () => {
+  test("uses the preferred state directory when available", async () => {
+    await using tmp = await tmpdir()
+    const preferred = path.join(tmp.path, "preferred")
+
+    expect(await resolveState(preferred, path.join(tmp.path, "fallback"))).toBe(preferred)
+    expect((await fs.stat(preferred)).isDirectory()).toBe(true)
+    expect(await fs.readdir(preferred)).toEqual([])
+  })
+
+  test("falls back when the default state directory is unusable", async () => {
+    await using tmp = await tmpdir()
+    const preferred = path.join(tmp.path, "preferred")
+    const fallback = path.join(tmp.path, "data", "state")
+    await fs.writeFile(preferred, "not a directory")
+
+    expect(await resolveState(preferred, fallback)).toBe(fallback)
+    expect((await fs.stat(fallback)).isDirectory()).toBe(true)
+  })
+
+  test("keeps using an existing fallback", async () => {
+    await using tmp = await tmpdir()
+    const preferred = path.join(tmp.path, "preferred")
+    const fallback = path.join(tmp.path, "fallback")
+    await fs.mkdir(fallback)
+
+    expect(await resolveState(preferred, fallback)).toBe(fallback)
+    expect(
+      await fs.stat(preferred).then(
+        () => true,
+        () => false,
+      ),
+    ).toBe(false)
+  })
+
+  test.skipIf(skip)("uses the preferred directory when an existing fallback is not writable", async () => {
+    await using tmp = await tmpdir()
+    const preferred = path.join(tmp.path, "preferred")
+    const fallback = path.join(tmp.path, "fallback")
+    await fs.mkdir(fallback)
+    await fs.chmod(fallback, 0o500)
+
+    try {
+      expect(await resolveState(preferred, fallback)).toBe(preferred)
+    } finally {
+      await fs.chmod(fallback, 0o700)
+    }
+  })
+
+  test.skipIf(skip)("falls back when the preferred directory cannot be created", async () => {
+    await using tmp = await tmpdir()
+    const parent = path.join(tmp.path, "preferred")
+    const preferred = path.join(parent, "kilo")
+    const fallback = path.join(tmp.path, "data", "state")
+    await fs.mkdir(parent)
+    await fs.chmod(parent, 0o500)
+
+    try {
+      expect(await resolveState(preferred, fallback)).toBe(fallback)
+    } finally {
+      await fs.chmod(parent, 0o700)
+    }
+  })
+
+  test.skipIf(skip)("falls back when the preferred directory exists but is not writable", async () => {
+    await using tmp = await tmpdir()
+    const preferred = path.join(tmp.path, "preferred")
+    const fallback = path.join(tmp.path, "data", "state")
+    await fs.mkdir(preferred)
+    await fs.chmod(preferred, 0o500)
+
+    try {
+      expect(await resolveState(preferred, fallback)).toBe(fallback)
+    } finally {
+      await fs.chmod(preferred, 0o700)
+    }
+  })
+
+  test("preserves errors for explicitly configured state directories", async () => {
+    await using tmp = await tmpdir()
+    const preferred = path.join(tmp.path, "preferred")
+    await fs.writeFile(preferred, "not a directory")
+
+    const err = await resolveState(preferred).catch((err: unknown) => err)
+    expect(err).toBeInstanceOf(Error)
+  })
+
+  test("reports both paths when the fallback also fails", async () => {
+    await using tmp = await tmpdir()
+    const preferred = path.join(tmp.path, "preferred")
+    const fallback = path.join(tmp.path, "fallback")
+    await Promise.all([fs.writeFile(preferred, "not a directory"), fs.writeFile(fallback, "not a directory")])
+
+    const err = await resolveState(preferred, fallback).catch((err: unknown) => err)
+    expect(err).toBeInstanceOf(AggregateError)
+    if (!(err instanceof AggregateError)) throw err
+    expect(err.message).toContain(preferred)
+    expect(err.message).toContain(fallback)
+    expect(err.errors).toHaveLength(2)
+  })
+})