diff --git a/.agents/skills/unidesk-trans/SKILL.md b/.agents/skills/unidesk-trans/SKILL.md
index eaa4f83f..f1539367 100644
--- a/.agents/skills/unidesk-trans/SKILL.md
+++ b/.agents/skills/unidesk-trans/SKILL.md
@@ -20,6 +20,10 @@ trans D601:win/c/test cat README.md
 trans D601:win/c/test rg -i needle .
 trans D601:win/c/test git diff --check
 trans D601:win/c/test git commit -m 'fix: update docs'
+trans D601:win/c/test git exact-commit status
+trans D601:win/c/test git exact-commit plan --path src/main.c
+trans D601:win/c/test git exact-commit run --path src/main.c --message 'fix: exact change' --confirm
+trans D601:win/c/test git exact-commit gc-auto --confirm
 trans gh:/owner/repo/issue/<number> cat
 ```
 
@@ -57,6 +61,12 @@ Host workspace、k3s、Windows、GitHub issue/PR route 见 [references/routes.md
 - Windows workspace 中依赖 Windows PATH、解释器或工具链的命令优先走 `<provider>:win/<drive>/<path> cmd|ps`；不得因同一 WSL provider 的 host/WSL plane 缺少 `python`、编译器或其他命令，就判断 Windows plane 也未安装。Windows Python 例如 `trans G14-WSL:win/d/Work/CONSTAR_workspace cmd python --version`。
 - `/mnt/<drive>` workspace 的命令返回 `command not found` 时，CLI 会输出对应 `:win/<drive>/... cmd` 的 `UNIDESK_SSH_HINT`；该提示只建议核对 Windows plane，不改变原命令退出码。
 - Windows `git` helper 拒绝包含 `%` format 等需 shell review 的复杂参数时，按错误提示改用 `trans <route>:win/... ps '<PowerShell command>'`，不要反复改写 direct `git` argv 绕过校验。
+- Windows 固定脏 worktree 的精确提交规则：
+  - 使用 `git exact-commit plan` 明确列出一个或多个 `--path`；
+  - `run` 必须提供 `--message` 和 `--confirm`；
+  - helper 使用临时 index 和 HEAD old-value CAS，只更新选中路径的 index，并验证未选中路径的 staged/unstaged 状态不变；
+  - `status` 只读披露 `git count-objects -v`；
+  - `gc-auto` 只调用 Git 自身的 `git gc --auto`，保留 reflog 和 recent-object 规则，禁止直接 `git prune`。
 - 从本地 Bash 调用一行 Windows `ps` 时，PowerShell 表达式外层使用单引号，保护 `$`、`$_` 和 `$_.Property` 不被本地 shell 提前展开；复杂或多行 PowerShell 改用 `ps <<'PS'` heredoc。
 - 单行 `ps` 源码若因本地 shell 展开而以缺失左值的 `=` 开始，CLI 在远端执行前返回 `ssh-windows-powershell-local-expansion`，并给出 `$p`、`$_` 的单引号示例和 quoted `PS` heredoc。
 - 扩展 Windows helper 时保持 operation-scoped PowerShell payload；不要把多操作大脚本塞进 single `EncodedCommand`。
diff --git a/docs/reference/cli.md b/docs/reference/cli.md
index 0a60dfb9..32ae3309 100644
--- a/docs/reference/cli.md
+++ b/docs/reference/cli.md
@@ -502,6 +502,13 @@ PATCH
 
 通过 `trans <providerId>` 执行多行脚本时，优先使用结构化 helper，例如 `trans G14 py < script.py`、`trans G14 sh <<'SH'` 或 `trans G14:k3s sh <<'SH'`。不要在远端命令字符串里再嵌套 heredoc、复杂引号或 `ssh 'python3 - <<EOF ...'` 形态；多层 shell 解析容易把 stdin 绑定到错误进程，结果会打开远端交互解释器并留下悬挂的 broker/SSH 会话。长脚本需要复用时，优先提交到 repo 或通过 stdin 传输到目标节点执行。
 
+- Windows 固定脏 worktree 精确提交入口：
+  - `trans <route>:win/... git exact-commit status` 只读披露对象数量与安全停止边界；
+  - `plan --path <repo-relative-path>` 使用临时 index 生成待提交 tree，不更新 ref；
+  - `run --path <path> --message <message> --confirm` 使用 HEAD old-value CAS 更新当前分支，只刷新选中路径的 index，并验证未选中路径的 staged/unstaged 状态不变；
+  - 多文件必须重复传入 `--path`，禁止把当前 index 当作隐式提交范围；
+  - `gc-auto --confirm` 只运行 `git gc --auto`，不得直接 prune active、recent 或受 reflog 保护的 unreachable objects。
+
 ## Remote Main Server Passthrough
 
 `--main-server-ip` 是一个全局前缀，必须放在需要透传的命令同一次调用中，例如 `bun scripts/cli.ts --main-server-ip 74.48.78.17 debug health`。默认传输是公网 frontend：本地 CLI 读取本仓库 `config.json` 中的 frontend 登录账号密码，登录 `http://<ip>:<frontendPort>/` 获取 HttpOnly session cookie，然后通过 frontend 的 `/api/*` 同源代理访问 backend-core 内网 API；因此计算节点只需要能访问公网 frontend，不需要主 server SSH key，也不需要打开 backend-core REST API 或 PostgreSQL 端口。
diff --git a/scripts/src/help.ts b/scripts/src/help.ts
index b5e9cd01..b14dda08 100644
--- a/scripts/src/help.ts
+++ b/scripts/src/help.ts
@@ -202,6 +202,9 @@ export function sshHelp(): unknown {
       "trans D601:win/c/test git status --short --branch",
       "trans D601:win/c/test git diff --check",
       "trans D601:win/c/test git commit -m 'fix: update docs'",
+      "trans D601:win/c/test git exact-commit status",
+      "trans D601:win/c/test git exact-commit plan --path src/main.c",
+      "trans D601:win/c/test git exact-commit run --path src/main.c --message 'fix: exact change' --confirm",
       "trans D601:win skills [--scope agents|codex|all] [--limit N]",
       "trans NC01:k3s",
       "trans NC01:k3s kubectl get pods -n hwlab-dev",
diff --git a/scripts/src/ssh.test.ts b/scripts/src/ssh.test.ts
index e955bd0d..0f26b875 100644
--- a/scripts/src/ssh.test.ts
+++ b/scripts/src/ssh.test.ts
@@ -82,6 +82,22 @@ describe("ssh windows fs read-only operations", () => {
     expect(commitInvocation.parsed.requiresStdin).toBe(false);
   });
 
+  test("builds controlled exact-commit and object status helpers", () => {
+    const status = parseSshInvocation("D601:win/F/Work/ConStart", ["git", "exact-commit", "status"]);
+    const plan = parseSshInvocation("D601:win/F/Work/ConStart", ["git", "exact-commit", "plan", "--path", "src/main.c"]);
+    const run = parseSshInvocation("D601:win/F/Work/ConStart", ["git", "exact-commit", "run", "--path", "src/main.c", "--message", "fix: exact", "--confirm"]);
+    const decoded = decodedWindowsPowerShellCommand(run.parsed.remoteCommand);
+
+    expect(status.parsed.invocationKind).toBe("helper");
+    expect(plan.parsed.invocationKind).toBe("helper");
+    expect(decoded).toContain("GIT_INDEX_FILE");
+    expect(decoded).toContain("update-ref");
+    expect(decoded).toContain("unselected worktree/index fingerprint");
+    expect(decoded).toContain("old-value CAS");
+    expect(() => parseSshInvocation("D601:win/F/Work/ConStart", ["git", "exact-commit", "run", "--path", "src/main.c", "--message", "fix: exact"])).toThrow("requires --confirm");
+    expect(() => parseSshInvocation("D601:win/F/Work/ConStart", ["git", "exact-commit", "plan", "--path", "../secret"])).toThrow("must stay inside");
+  });
+
   test("builds bounded UTF-8 scripts for cat, ls, and rg", () => {
     const catScript = windowsFsReadOnlyScript("F:\\Work\\demo", "cat", ["--max-bytes", "4096", "中文.md"]);
     const lsScript = windowsFsReadOnlyScript("F:\\Work\\demo", "ls", ["-la", "--limit=5"]);
diff --git a/scripts/src/ssh.ts b/scripts/src/ssh.ts
index cff9a9bd..27eaa0b7 100644
--- a/scripts/src/ssh.ts
+++ b/scripts/src/ssh.ts
@@ -596,6 +596,13 @@ function windowsUnsupportedOperationMessage(route: ParsedSshRoute, operation: st
 function parseWindowsGitInvocation(route: ParsedSshRoute, gitArgs: string[]): ParsedSshArgs {
   const subcommand = gitArgs[0] ?? "";
   if (subcommand.length === 0) throw new Error(`ssh ${route.raw} git requires a git subcommand, for example: ${sshDisplayEntrypoint()} ${route.raw} git status --short --branch`);
+  if (subcommand === "exact-commit") {
+    return {
+      remoteCommand: buildWindowsPowerShellInvocation(windowsGitExactCommitScript(route, gitArgs.slice(1))),
+      requiresStdin: false,
+      invocationKind: "helper",
+    };
+  }
   if (subcommand === "commit") validateWindowsGitCommitArgs(route, gitArgs);
   const commandLine = ["git", ...gitArgs].map((value) => windowsCmdArgument(value, route)).join(" ");
   return {
@@ -605,6 +612,106 @@ function parseWindowsGitInvocation(route: ParsedSshRoute, gitArgs: string[]): Pa
   };
 }
 
+function windowsGitExactCommitScript(route: ParsedSshRoute, args: string[]): string {
+  const operation = args[0] ?? "";
+  if (!new Set(["status", "plan", "run", "gc-auto"]).has(operation)) {
+    throw new Error("ssh win git exact-commit requires status, plan, run, or gc-auto");
+  }
+  const paths: string[] = [];
+  let message = "";
+  let confirm = false;
+  for (let index = 1; index < args.length; index += 1) {
+    const arg = args[index] ?? "";
+    if (arg === "--path") {
+      const value = args[index + 1];
+      if (!value) throw new Error("git exact-commit --path requires a repository-relative path");
+      if (/^(?:[A-Za-z]:|[\\/])|(?:^|[\\/])\.\.(?:[\\/]|$)/u.test(value)) throw new Error("git exact-commit --path must stay inside the repository");
+      paths.push(value.replace(/\\/gu, "/"));
+      index += 1;
+      continue;
+    }
+    if (arg === "--message") {
+      const value = args[index + 1];
+      if (!value) throw new Error("git exact-commit --message requires a value");
+      message = value;
+      index += 1;
+      continue;
+    }
+    if (arg === "--confirm") {
+      confirm = true;
+      continue;
+    }
+    throw new Error(`unsupported git exact-commit option: ${arg}`);
+  }
+  if ((operation === "plan" || operation === "run") && paths.length === 0) throw new Error(`git exact-commit ${operation} requires at least one --path`);
+  if (operation === "run" && message.length === 0) throw new Error("git exact-commit run requires --message");
+  if ((operation === "run" || operation === "gc-auto") && !confirm) throw new Error(`git exact-commit ${operation} requires --confirm`);
+  const cwd = powerShellSingleQuote(route.workspace ?? ".");
+  const pathList = paths.map((value) => powerShellSingleQuote(value)).join(",");
+  return `$ErrorActionPreference='Stop'
+$ProgressPreference='SilentlyContinue'
+[Console]::InputEncoding=[System.Text.UTF8Encoding]::new()
+[Console]::OutputEncoding=[System.Text.UTF8Encoding]::new()
+$OutputEncoding=[System.Text.UTF8Encoding]::new()
+Set-Location -LiteralPath ${cwd}
+$operation=${powerShellSingleQuote(operation)}
+$paths=@(${pathList})
+$message=${powerShellSingleQuote(message)}
+function Invoke-Git([string[]]$GitArgs) {
+  $output = @(& git @GitArgs 2>&1)
+  if ($LASTEXITCODE -ne 0) { throw (($output | ForEach-Object { $_.ToString() }) -join [Environment]::NewLine) }
+  return (($output | ForEach-Object { $_.ToString() }) -join [Environment]::NewLine).Trim()
+}
+function Object-Status {
+  $values=@{}
+  (Invoke-Git @('count-objects','-v')).Split([Environment]::NewLine) | ForEach-Object { $pair=$_.Split(':',2); if($pair.Count -eq 2){$values[$pair[0].Trim()]=[int64]$pair[1].Trim()} }
+  return $values
+}
+$before=Object-Status
+$head=Invoke-Git @('rev-parse','--verify','HEAD^{commit}')
+$branch=Invoke-Git @('symbolic-ref','-q','HEAD')
+if($operation -eq 'status') {
+  [ordered]@{ok=$true;operation=$operation;head=$head;branch=$branch;objects=$before;safeStop='read-only; no objects were pruned'} | ConvertTo-Json -Depth 8 -Compress
+  exit 0
+}
+if($operation -eq 'gc-auto') {
+  $gcOutput=Invoke-Git @('gc','--auto')
+  $after=Object-Status
+  [ordered]@{ok=$true;operation=$operation;head=$head;before=$before;after=$after;gcOutput=$gcOutput;safeStop='git gc --auto only; Git recent-object and reflog retention remain authoritative; no direct prune'} | ConvertTo-Json -Depth 8 -Compress
+  exit 0
+}
+$gitDir=Invoke-Git @('rev-parse','--path-format=absolute','--git-dir')
+$indexPath=Invoke-Git @('rev-parse','--path-format=absolute','--git-path','index')
+$unrelatedPathspec=@('.')+@($paths | ForEach-Object { ':(exclude)'+$_ })
+$unrelatedBefore=Invoke-Git (@('status','--porcelain=v2','--')+$unrelatedPathspec)
+$tempIndex=Join-Path $gitDir ('unidesk-exact-index-'+[Guid]::NewGuid().ToString('N'))
+try {
+  $env:GIT_INDEX_FILE=$tempIndex
+  [void](Invoke-Git @('read-tree',$head))
+  [void](Invoke-Git (@('add','--')+$paths))
+  $tree=Invoke-Git @('write-tree')
+  $parentTree=Invoke-Git @('rev-parse',($head+'^{tree}'))
+  if($tree -eq $parentTree){throw 'selected paths do not change the HEAD tree'}
+  if($operation -eq 'plan') {
+    [ordered]@{ok=$true;operation=$operation;head=$head;branch=$branch;tree=$tree;paths=$paths;tempIndex=$tempIndex;objectsBefore=$before;safeStop='plan only; ref and original index unchanged'} | ConvertTo-Json -Depth 8 -Compress
+    exit 0
+  }
+  $commit=($message | & git commit-tree $tree -p $head).Trim()
+  if($LASTEXITCODE -ne 0 -or !$commit){throw 'git commit-tree failed'}
+  [void](Invoke-Git @('update-ref','-m',('unidesk exact-commit: '+$message),$branch,$commit,$head))
+  Remove-Item Env:GIT_INDEX_FILE -ErrorAction SilentlyContinue
+  [void](Invoke-Git (@('reset',$commit,'--')+$paths))
+  $unrelatedAfter=Invoke-Git (@('status','--porcelain=v2','--')+$unrelatedPathspec)
+  if($unrelatedAfter -ne $unrelatedBefore){throw 'unselected worktree/index fingerprint changed after exact commit'}
+  $after=Object-Status
+  [ordered]@{ok=$true;operation=$operation;oldHead=$head;commit=$commit;tree=$tree;branch=$branch;paths=$paths;tempIndex=$tempIndex;unselectedStateUnchanged=$true;selectedPathsIndexUpdated=$true;objectsBefore=$before;objectsAfter=$after;safeStop='ref updated with old-value CAS; no prune performed'} | ConvertTo-Json -Depth 8 -Compress
+} finally {
+  Remove-Item Env:GIT_INDEX_FILE -ErrorAction SilentlyContinue
+  Remove-Item -LiteralPath $tempIndex -Force -ErrorAction SilentlyContinue
+  Remove-Item -LiteralPath ($tempIndex+'.lock') -Force -ErrorAction SilentlyContinue
+}`;
+}
+
 function validateWindowsGitCommitArgs(route: ParsedSshRoute, gitArgs: string[]): void {
   const hasNonInteractiveMessage = gitArgs.slice(1).some((arg) => (
     arg === "--dry-run" ||