diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c245f17..3a56f2f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -63,6 +63,7 @@ jobs:
       - run: pnpm verify:imported-avatar-current-inputs
       - run: pnpm avatar:verify:compatibility
       - run: pnpm check:core
+      - run: node --test tooling/release/workstream.test.mjs
 
   push-checks:
     needs: [scope, docs, core]
diff --git a/.github/workflows/packages.yml b/.github/workflows/packages.yml
index 237512d..0efe355 100644
--- a/.github/workflows/packages.yml
+++ b/.github/workflows/packages.yml
@@ -96,8 +96,8 @@ jobs:
         run: |
           $root=Join-Path $env:RUNNER_TEMP 'world-packages'
           $env:AIW_SMOKE_NO_SYSTEM_GIT='1'
-          ./tooling/release/install-smoke.ps1 -Installer "$root\AgentIntersect-World-0.15.0-rc.2-windows.2-windows-x64-setup.exe" -SmokeTest "$env:GITHUB_WORKSPACE\tooling\release\launch.test.mjs" -Receipt "$root\windows-smoke.json"
-          $file=Get-Item "$root\AgentIntersect-World-0.15.0-rc.2-windows.2-windows-x64-setup.exe"
+          ./tooling/release/install-smoke.ps1 -Installer "$root\AgentIntersect-World-0.15.0-rc.2-windows.3-windows-x64-setup.exe" -SmokeTest "$env:GITHUB_WORKSPACE\tooling\release\launch.test.mjs" -Receipt "$root\windows-smoke.json"
+          $file=Get-Item "$root\AgentIntersect-World-0.15.0-rc.2-windows.3-windows-x64-setup.exe"
           ((Get-FileHash $file.FullName -Algorithm SHA256).Hash.ToLower()+'  '+$file.Name) | Set-Content "$root\WINDOWS-SHA256SUMS" -Encoding utf8NoBOM
       - uses: actions/upload-artifact@v7
         with:
diff --git a/apps/local-server/src/workstream-routes.ts b/apps/local-server/src/workstream-routes.ts
index 2167662..4aa2dd5 100644
--- a/apps/local-server/src/workstream-routes.ts
+++ b/apps/local-server/src/workstream-routes.ts
@@ -2,6 +2,7 @@ import { MAX_PROMPT_BYTES } from "@agentintersect-world/agent-session-protocol";
 import type { FastifyInstance, FastifyReply, FastifyRequest } from "fastify";
 import type { PreviewManagerService } from "./preview-manager-service.js";
 import { WorkstreamSourceError } from "./workstream-start-source.js";
+import { WorktreeAuthorityError } from "./worktree-authority.js";
 
 import {
   WorkstreamService,
@@ -85,6 +86,19 @@ function fail(
   reply: FastifyReply,
   envelope: RouteEnvelope,
 ) {
+  if (error instanceof WorktreeAuthorityError) {
+    return reply
+      .code(error.code === "unavailable" ? 503 : 409)
+      .send(
+        envelope.failure(
+          request,
+          error.code === "unavailable" ? "unavailable" : "conflict",
+          error.code === "git-failed"
+            ? "Git could not complete the Workstream operation. Check the selected branch, commit and worktree permissions."
+            : error.message,
+        ),
+      );
+  }
   if (error instanceof WorkstreamSourceError)
     error = new WorkstreamServiceError("validation", error.message);
   if (!(error instanceof WorkstreamServiceError)) throw error;
diff --git a/apps/local-server/src/workstream-service.ts b/apps/local-server/src/workstream-service.ts
index 8509213..ec14d58 100644
--- a/apps/local-server/src/workstream-service.ts
+++ b/apps/local-server/src/workstream-service.ts
@@ -372,7 +372,7 @@ function optionalRead(path: string): Promise<string | null> {
 }
 
 async function syncFile(path: string): Promise<void> {
-  const handle = await open(path, "r");
+  const handle = await open(path, "r+");
   try {
     await handle.sync();
   } finally {
diff --git a/apps/local-server/src/worktree-authority.ts b/apps/local-server/src/worktree-authority.ts
index fc85166..fcb7d24 100644
--- a/apps/local-server/src/worktree-authority.ts
+++ b/apps/local-server/src/worktree-authority.ts
@@ -718,7 +718,10 @@ export class WorktreeAuthority {
       );
     return {
       ...boundary,
-      relativePath: relative(boundary.allowedParent, input.worktreePath),
+      relativePath: relative(
+        boundary.allowedParent,
+        join(parent, basename(input.worktreePath)),
+      ),
     };
   }
 
@@ -833,7 +836,11 @@ export class WorktreeAuthority {
       registered.exitCode !== 0 ||
       !registered.stdout
         .split(/\r?\n/)
-        .some((line) => line === `worktree ${input.worktreePath}`)
+        .some(
+          (line) =>
+            line.startsWith("worktree ") &&
+            resolve(line.slice("worktree ".length)) === input.worktreePath,
+        )
     )
       throw new WorktreeAuthorityError(
         "git-refused",
diff --git a/apps/local-server/test/workstream-api.test.ts b/apps/local-server/test/workstream-api.test.ts
index c606f7d..f9013d3 100644
--- a/apps/local-server/test/workstream-api.test.ts
+++ b/apps/local-server/test/workstream-api.test.ts
@@ -75,6 +75,30 @@ afterEach(async () => {
 });
 
 describe("Workstream API", () => {
+  it("reports a Git worktree refusal instead of an opaque server error", async () => {
+    const server = await fixture();
+    try {
+      const response = await server.inject({
+        method: "POST",
+        url: "/workstreams",
+        payload: {
+          requestId: "request-refused",
+          correlationId: "correlation-refused",
+          title: "Start from missing commit",
+          task: "Start from missing commit",
+          startPoint: "a".repeat(40),
+          repository,
+          agent,
+        },
+      });
+      expect(response.statusCode).toBe(409);
+      expect(response.json().error).toMatchObject({ code: "conflict" });
+      expect(response.json().error.message).not.toBe("Internal server error");
+      expect(response.json().error.message).toMatch(/commit/i);
+    } finally {
+      await server.close();
+    }
+  });
   it("creates, reads, and idempotently cancels one owned workstream", async () => {
     const server = await fixture();
     const createBody = {
diff --git a/docs/internal/WINDOWS_BUNDLED_GIT_CANDIDATE.md b/docs/internal/WINDOWS_BUNDLED_GIT_CANDIDATE.md
index af13878..aea7651 100644
--- a/docs/internal/WINDOWS_BUNDLED_GIT_CANDIDATE.md
+++ b/docs/internal/WINDOWS_BUNDLED_GIT_CANDIDATE.md
@@ -1,5 +1,13 @@
 # Windows installer: bundled Git and proportional icon
 
+## Current correction — native Workstream lifecycle
+
+Aaron authorized the native Workstream fix, source-first PR/green CI/merge, and affected installer rebuilds (Discord 1557886044173766749). Reproduction on shipped Windows Node/Git showed a registered worktree rejected because Git reports forward slashes. The native lifecycle regression also exposed short-name versus real-path relative receipts and Windows read-only-handle fsync EPERM during cancellation. Normalize registration paths, derive relative receipts from the validated canonical parent, and open owned persistence files read/write before fsync. Keep all existing ownership checks and propagate bounded authority errors without raw Git stderr.
+
+The native packaged API regression must create, restore and cancel against real Git using disposable state; synthetic agent references do not claim real harness acceptance. Historical RED and corrected local GREEN are separate from final clean-package proof. Next Windows setup: `0.15.0-rc.2-windows.3`, numeric `0.15.0.5`; AppId/destination/state unchanged. Rebuild Windows ZIP/setup and Linux DEB/tar only after merged-main CI; then repin the npm bootstrap through a separate source-first PR against those fixed archive bytes. Private delivery only, no publication/provider/TEST45495 changes. Never automatically delete branches/worktrees left by earlier failed user attempts.
+
+## Previous candidates (historical)
+
 Authorized by Aaron (Discord 1557792944902373429): rebuild private Windows setup, install over the prior candidate, preserve state, include private Portable Git so project creation works without system Git, and derive the installer/shortcut icon from the supplied agentintersect_appicon.svg without distortion.
 
 Base: merged main 3c4b358. Scope: Windows packaging/launcher, icon generation, focused package tests and native isolated proof. Keep AppId/default directory/state paths unchanged. No machine/user PATH or global Git config writes; do not invent commit identity. Provider changes, public uploads/releases and TEST45495 mutation remain excluded.
diff --git a/tooling/release/README.md b/tooling/release/README.md
index eb0eb5e..f249042 100644
--- a/tooling/release/README.md
+++ b/tooling/release/README.md
@@ -12,7 +12,7 @@ Linux packages are not for musl/Alpine or ARM. For headless/remote sessions use
 
 ## Windows x64
 
-Run `AgentIntersect-World-0.15.0-rc.2-windows.2-windows-x64-setup.exe`. Close World’s console before installing over the earlier copy; keep the same destination. The installer keeps its original AppId and state location. It bundles private Git for World and child processes without changing Windows PATH or your Git identity/configuration. First launch initializes this private Git tree. This is a per-user installer: a Start Menu shortcut and registered uninstaller are created. The installer is **unsigned**, so Windows SmartScreen or antivirus may warn. Verify its published SHA-256 checksum and source before running; do not assume a warning means the file was signed or vetted. No administrator access or PATH change is requested. Close the console with `quit` + Enter or Ctrl+C.
+Run `AgentIntersect-World-0.15.0-rc.2-windows.3-windows-x64-setup.exe`. Close World’s console before installing over the earlier copy; keep the same destination. The installer keeps its original AppId and state location. It bundles private Git for World and child processes without changing Windows PATH or your Git identity/configuration. First launch initializes this private Git tree. This is a per-user installer: a Start Menu shortcut and registered uninstaller are created. The installer is **unsigned**, so Windows SmartScreen or antivirus may warn. Verify its published SHA-256 checksum and source before running; do not assume a warning means the file was signed or vetted. No administrator access or PATH change is requested. Close the console with `quit` + Enter or Ctrl+C.
 
 ## State and integrations
 
diff --git a/tooling/release/build.py b/tooling/release/build.py
index 4a579d3..14c5b5d 100644
--- a/tooling/release/build.py
+++ b/tooling/release/build.py
@@ -289,7 +289,7 @@ def main():
                     "platform": platform,
                     "runtime": provenance,
                     "git": git_provenance,
-                    "windowsInstallerVersion": "0.15.0-rc.2-windows.2" if platform == "windows-x64" else None,
+                    "windowsInstallerVersion": "0.15.0-rc.2-windows.3" if platform == "windows-x64" else None,
                     "deploymentTool": "pnpm12.4.2",
                     "signed": False,
                 },
diff --git a/tooling/release/windows.iss b/tooling/release/windows.iss
index 9a04eda..fa8bccf 100644
--- a/tooling/release/windows.iss
+++ b/tooling/release/windows.iss
@@ -5,7 +5,7 @@
   #error OutputPath is required
 #endif
 #ifndef ReleaseVersion
-  #define ReleaseVersion "0.15.0-rc.2-windows.2"
+  #define ReleaseVersion "0.15.0-rc.2-windows.3"
 #endif
 [Setup]
 AppId=AgentIntersectWorld
@@ -26,9 +26,9 @@ LicenseFile={#PackageRoot}\LICENSE
 InfoBeforeFile=installer-notice.txt
 OutputDir={#OutputPath}
 OutputBaseFilename=AgentIntersect-World-{#ReleaseVersion}-windows-x64-setup
-VersionInfoVersion=0.15.0.4
+VersionInfoVersion=0.15.0.5
 VersionInfoProductName=AgentIntersect World
-VersionInfoProductVersion=0.15.0.4
+VersionInfoProductVersion=0.15.0.5
 VersionInfoProductTextVersion={#ReleaseVersion}
 Compression=lzma2/normal
 SolidCompression=yes
diff --git a/tooling/release/workstream.test.mjs b/tooling/release/workstream.test.mjs
new file mode 100644
index 0000000..68ced5c
--- /dev/null
+++ b/tooling/release/workstream.test.mjs
@@ -0,0 +1,127 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import { execFileSync } from "node:child_process";
+import { mkdir, mkdtemp, writeFile, rm } from "node:fs/promises";
+import { tmpdir } from "node:os";
+import { join, resolve } from "node:path";
+import { pathToFileURL } from "node:url";
+
+const load = (name) =>
+  import(pathToFileURL(resolve(`apps/local-server/dist/${name}.js`)).href);
+
+test(
+  "packaged Workstream API creates, restores and cancels a registered worktree",
+  { timeout: 60000 },
+  async () => {
+    const root = await mkdtemp(join(tmpdir(), "aiw-workstream-package-"));
+    const repositoryRoot = join(root, "sample repo");
+    const worktreeParent = join(root, "worktrees");
+    const previousPath = process.env.PATH;
+    if (process.platform === "win32")
+      process.env.PATH = `${resolve("runtime/git/cmd")};${previousPath}`;
+    const git = (...args) =>
+      execFileSync("git", ["-C", repositoryRoot, ...args], {
+        encoding: "utf8",
+        env: {
+          ...process.env,
+          GIT_CONFIG_NOSYSTEM: "1",
+          GIT_CONFIG_GLOBAL: join(root, "empty.gitconfig"),
+        },
+      });
+    let server;
+    let service;
+    let authority;
+    try {
+      await mkdir(repositoryRoot);
+      await mkdir(worktreeParent);
+      await writeFile(join(root, "empty.gitconfig"), "");
+      git("init", "--initial-branch=master");
+      git("config", "user.name", "Disposable Workstream Test");
+      git("config", "user.email", "test@example.invalid");
+      await writeFile(
+        join(repositoryRoot, "README.md"),
+        "Native package fixture\n",
+      );
+      git("add", "README.md");
+      git("commit", "-m", "fixture");
+      const { WorktreeAuthority } = await load("worktree-authority");
+      const { WorkstreamService } = await load("workstream-service");
+      const { createLocalServer } = await load("server");
+      const repository = {
+        repositoryId: "repo-package",
+        revision: "repo-rev-1",
+      };
+      const agent = {
+        agentId: "fixture-agent",
+        nativeSessionId: "fixture-session",
+        rootNativeSessionId: "fixture-session",
+        revision: "agent-rev-1",
+      };
+      authority = new WorktreeAuthority({
+        approvedRepositoryRoot: repositoryRoot,
+        allowedWorktreeParent: worktreeParent,
+      });
+      service = new WorkstreamService({
+        directory: join(root, "store"),
+        worktreeAuthority: authority,
+        currentRepository: () => repository,
+        connectedAgent: () => agent,
+        evidenceReader: { read: async () => [] },
+        id: () => "workstream-package",
+      });
+      server = createLocalServer({ workstreamService: service });
+      const response = await server.inject({
+        method: "POST",
+        url: "/workstreams",
+        payload: {
+          requestId: "create-package",
+          correlationId: "create-package",
+          title: "Create native workstream",
+          task: "Create native workstream",
+          startPoint: "HEAD",
+          prIntent: "local",
+          repository,
+          agent,
+        },
+      });
+      assert.equal(response.statusCode, 201, response.body);
+      const workstream = response.json().data.workstream;
+      assert.equal(workstream.status, "working");
+      assert.equal(
+        (await authority.restore(workstream.authority)).state,
+        "current",
+      );
+      const cancelled = await server.inject({
+        method: "POST",
+        url: "/workstreams/workstream-package/cancel",
+        payload: {
+          requestId: "cancel-package",
+          correlationId: "cancel-package",
+          expectedRevision: workstream.revision,
+          repository,
+          agent,
+        },
+      });
+      assert.equal(cancelled.statusCode, 200, cancelled.body);
+      assert.equal(cancelled.json().data.workstream.worktreeState, "removed");
+      assert.equal(
+        git("worktree", "list", "--porcelain")
+          .split(/\r?\n/)
+          .filter((line) => line.startsWith("worktree ")).length,
+        1,
+      );
+    } finally {
+      await server?.close();
+      await service?.dispose();
+      await authority?.dispose();
+      if (previousPath === undefined) delete process.env.PATH;
+      else process.env.PATH = previousPath;
+      await rm(root, {
+        recursive: true,
+        force: true,
+        maxRetries: 5,
+        retryDelay: 200,
+      });
+    }
+  },
+);