fix(gitcmd): bind host storage to the resolved repository

Problem: ambient Git index/object variables can redirect host worktree preparation and object access.

Root cause: pinned Git/common/worktree directories do not override GIT_INDEX_FILE, GIT_OBJECT_DIRECTORY or GIT_ALTERNATE_OBJECT_DIRECTORIES. The shared constructors retained them.

Fix: remove those three ambient overrides in Env and Detached. Keep deliberate host private-index/object overrides and repository-declared alternates. Cover actual delivery/candidate preparation and a Boot isolated-write/apply flow.

Verification: all 239 root packages pass across disjoint required/rest commands; complete gitcmd/worktree/isolation race 306 passes; Boot race four passes. Exact preceding owner compiles and fails 18 regression events while seven controls pass. Full lint, vet and make check pass with byte-identical baseline. Windows/Linux builds compile; local literal Windows inventory verifies 25 required events and three package terminals, not native execution.

.github/workflows/ci.yml

@@ -421,6 +421,56 @@ jobs:
           retention-days: 7
 
 
+      - name: test (Windows Git storage environment)
+        if: env.RUN_STEPS == 'true' && runner.os == 'Windows' && github.event_name == 'pull_request'
+        timeout-minutes: 5
+        shell: bash
+        run: |
+          set -o pipefail
+          go test -count=1 -timeout=3m -json -run '^Test(HostStorageEnvironment|HostObjectStorage|HostExplicitStorageControls|DetachedStorageEnvironment|WorktreePreparationOwnsItsIndex|EffectIsolatedTaskOwnsGitStorage)$' ./internal/platform/gitcmd ./internal/platform/worktree ./internal/assembly/boot | tee "$RUNNER_TEMP/git-storage-environment.jsonl"
+          jq -se '
+            [.[] | select(.Test == null and .Action == "pass") | .Package] as $packages |
+            [.[] | select(.Test != null and .Action == "pass") | .Test] as $tests |
+            all(.[]; .Action != "skip" and .Action != "fail") and
+            (["reasonix/internal/platform/gitcmd", "reasonix/internal/platform/worktree", "reasonix/internal/assembly/boot"] - $packages | length) == 0 and
+            ([
+              "TestDetachedStorageEnvironment",
+              "TestDetachedStorageEnvironment/explicit_env",
+              "TestDetachedStorageEnvironment/inherited_env",
+              "TestEffectIsolatedTaskOwnsGitStorage",
+              "TestEffectIsolatedTaskOwnsGitStorage/ambient_existing",
+              "TestEffectIsolatedTaskOwnsGitStorage/ambient_missing",
+              "TestEffectIsolatedTaskOwnsGitStorage/control",
+              "TestHostExplicitStorageControls",
+              "TestHostExplicitStorageControls/explicit_object_directory",
+              "TestHostExplicitStorageControls/private_index",
+              "TestHostExplicitStorageControls/repository_declared_alternate",
+              "TestHostObjectStorage",
+              "TestHostObjectStorage/ambient_alternate_not_read",
+              "TestHostObjectStorage/writes_stay_in_repository",
+              "TestHostStorageEnvironment",
+              "TestHostStorageEnvironment/GIT_ALTERNATE_OBJECT_DIRECTORIES",
+              "TestHostStorageEnvironment/GIT_INDEX_FILE",
+              "TestHostStorageEnvironment/GIT_OBJECT_DIRECTORY",
+              "TestWorktreePreparationOwnsItsIndex",
+              "TestWorktreePreparationOwnsItsIndex/candidate_ambient_existing",
+              "TestWorktreePreparationOwnsItsIndex/candidate_ambient_missing",
+              "TestWorktreePreparationOwnsItsIndex/candidate_control",
+              "TestWorktreePreparationOwnsItsIndex/delivery_ambient_existing",
+              "TestWorktreePreparationOwnsItsIndex/delivery_ambient_missing",
+              "TestWorktreePreparationOwnsItsIndex/delivery_control"
+            ] - $tests | length) == 0
+          ' "$RUNNER_TEMP/git-storage-environment.jsonl"
+
+      - name: upload Windows Git storage environment inventory
+        if: always() && env.RUN_STEPS == 'true' && runner.os == 'Windows' && github.event_name == 'pull_request'
+        uses: actions/upload-artifact@cf430e030ddbb5b0abf93d22962f4752f3646cd9 # v7
+        with:
+          name: git-storage-environment-windows-${{ github.run_attempt }}
+          path: ${{ runner.temp }}/git-storage-environment.jsonl
+          if-no-files-found: ignore
+          retention-days: 7
+
       - name: test (Windows Anthropic interrupted usage)
         if: env.RUN_STEPS == 'true' && runner.os == 'Windows' && github.event_name == 'pull_request'
         timeout-minutes: 5

docs/GIT_STORAGE_ENVIRONMENT.md

@@ -0,0 +1,83 @@
+---
+owner: @SivanCola
+backup: @esengine
+status: active
+reviewed: 2026-10-26
+---
+
+# Host Git storage environment / 宿主 Git 存储环境
+
+## Behavior / 行为
+
+Host Git commands now remove ambient `GIT_INDEX_FILE`, `GIT_OBJECT_DIRECTORY`
+and `GIT_ALTERNATE_OBJECT_DIRECTORIES` before repository discovery, driver
+inspection and execution. Detached URL commands remove them too, whether their
+environment was explicit or inherited.
+
+宿主 Git 命令在仓库发现、驱动检查和执行前移除上述三个继承变量。按 URL 运行的
+Detached 命令也移除它们，包括显式环境和继承环境两种入口。
+
+Pinning a Git directory and common directory alone does not choose its index or
+object storage when these variables override them. See the official
+[Git repository environment contract](https://git-scm.com/docs/git#_the_git_repository).
+
+An inherited index could be overwritten while preparing another worktree;
+objects could be written outside the resolved repository or found only through
+an ambient alternate directory.
+
+仅固定 Git 目录和 common 目录，不能覆盖这些变量指定的索引和对象存储。旧实现
+创建另一个 worktree 时可改写外部索引；对象也可写入其他目录，或从继承的备用目录
+读取。这里修复宿主命令的环境准备，不把 cwd 或独立索引当作完整隔离。
+
+## Authority and compatibility / 权限与兼容
+
+| Boundary | Contract / 约定 |
+| --- | --- |
+| Ambient storage variables | Removed from host Git constructors and Detached / 两个共享入口均移除 |
+| Explicit host override | Trusted callers can append a private index or object directory after construction / 可信宿主仍可在构造后显式指定 |
+| Repository alternates | Existing objects/info/alternates remains effective / 仓库声明的备用对象库仍有效 |
+| User shell commands | Their environment is unchanged / 不改用户 shell 环境 |
+| Repository selection | Existing Open and Repo identity rules remain / 沿用仓库解析与固定身份 |
+| Credentials and transport | Existing secret filtering, SSH and network policy remain / 沿用密钥过滤、SSH 和网络策略 |
+
+Host commands previously relying on ambient storage relocation now use the
+resolved repository's storage. There is no migration of an existing external
+index or object database. Explicit private-index snapshot staging remains
+available. Legitimate linked worktrees still share their repository's common
+object database.
+
+此前依赖继承变量重定向存储的宿主命令，现在使用已解析仓库的存储；不迁移或修复
+已有外部索引和对象库。快照的显式私有索引仍有效；合法 linked worktree 仍共享
+仓库 common 对象库。
+
+Only three storage variables are covered. This is not a blanket Git environment
+allowlist, a sandbox, or authority against trusted explicit overrides, arbitrary
+shells, other writers, repository configuration or declared object alternates.
+No API, config, wire, persisted format, permission or model prefix changes.
+
+仅覆盖三个变量，不是完整 Git 环境白名单或沙箱，也不约束可信显式覆盖、任意
+shell、其他写入者、仓库配置和仓库声明的备用对象库。不改 API、配置、传输、持久化
+格式、权限或模型前缀。
+
+## Evidence and remaining work / 证据与未完成项
+
+Disposable real Git fixtures exercise object writes, ambient alternate reads,
+private-index staging, explicit object directories and declared alternates.
+Delivery and candidate preparation preserve an existing ambient index and do
+not create an absent one.
+
+Actual Boot delegates an isolated write and applies
+it, checking source-index bytes and that same ambient-index boundary.
+
+真实临时 Git 夹具覆盖对象写入、继承备用目录读取、私有索引、显式对象目录及仓库
+备用对象库。交付和候选 worktree 准备保留外部索引且不新建缺失索引。真实 Boot
+委派隔离写入并应用，核对源索引字节和相同外部索引边界。
+
+These are constructed regressions, not an observed user incident. They do not
+establish complete snapshots, actor CAS, hardlink protection, physical process
+quiescence, durable publication, cleanup recovery or the complete #14025 plan.
+Native execution and hosted results belong to each exact PR head separately.
+
+这些是构造回归，不是已观察到的用户事故；不能证明完整快照、逐 actor CAS、硬链接
+防护、物理进程静默、持久化发布、清理恢复或整个 #14025 方案完成。平台执行和 CI
+必须按各 PR 的精确 head 单独核验。

internal/assembly/boot/effect_git_storage_test.go

@@ -0,0 +1,106 @@
+package boot
+
+import (
+	"bytes"
+	"context"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"reasonix/internal/base/testenv"
+	"reasonix/internal/contract/config"
+	"reasonix/internal/contract/event"
+	"reasonix/internal/contract/provider"
+	"reasonix/internal/session/control"
+)
+
+func TestEffectIsolatedTaskOwnsGitStorage(t *testing.T) {
+	if _, err := exec.LookPath("git"); err != nil {
+		t.Skip("Git unavailable")
+	}
+	for _, mode := range []string{"ambient_existing", "ambient_missing", "control"} {
+		t.Run(mode, func(t *testing.T) {
+			home, root := statedBootHome(t), testenv.TempDir(t)
+			kind := "boot-git-storage-" + mode
+			rec := &isolationScriptProvider{dir: root, managed: filepath.Join(config.RootsForHome(home).DeliveryWorktreeDir(), "isolated")}
+			provider.Register(kind, func(provider.Config) (provider.Provider, error) { return rec, nil })
+			writeFile(t, root, "reasonix.toml", `
+default_model = "test-model"
+[agent]
+system_prompt = "BASE"
+worktree_isolation = true
+[codegraph]
+enabled = false
+[[providers]]
+name = "test-model"
+kind = "`+kind+`"
+model = "x"
+`)
+			gitInDir(t, root, "init", "-q")
+			mirrorToUserConfigAt(t, home, root)
+			gitInDir(t, root, "add", "-A")
+			gitInDir(t, root, "commit", "-q", "-m", "fixture")
+			index := filepath.Join(root, ".git", "index")
+			before, err := os.ReadFile(index)
+			if err != nil {
+				t.Fatal(err)
+			}
+			ambient := filepath.Join(testenv.TempDir(t), "ambient-index")
+			var original []byte
+			if mode == "ambient_existing" {
+				writeFile(t, root, "ambient-only.txt", "staged in another index\n")
+				for _, args := range [][]string{{"read-tree", "HEAD"}, {"add", "ambient-only.txt"}} {
+					cmd := exec.Command("git", append([]string{"-C", root}, args...)...)
+					cmd.Env = append(os.Environ(), "GIT_INDEX_FILE="+ambient)
+					if out, err := cmd.CombinedOutput(); err != nil {
+						t.Fatalf("ambient fixture: %v %s", err, out)
+					}
+				}
+				if err := os.Remove(filepath.Join(root, "ambient-only.txt")); err != nil {
+					t.Fatal(err)
+				}
+				original, err = os.ReadFile(ambient)
+				if err != nil {
+					t.Fatal(err)
+				}
+			}
+			if mode != "control" {
+				t.Setenv("GIT_INDEX_FILE", ambient)
+			}
+			ctrl, err := Build(context.Background(), Options{Home: home, WorkspaceRoot: root, Sink: event.Discard})
+			if err != nil {
+				t.Fatal(err)
+			}
+			t.Cleanup(ctrl.Close)
+			ctrl.SetToolApprovalMode(control.ToolApprovalYolo)
+			if err := ctrl.Run(t.Context(), "make out.txt without touching my tree until I say"); err != nil {
+				t.Fatal(err)
+			}
+			ctrl.Close()
+			if mode == "ambient_existing" {
+				after, err := os.ReadFile(ambient)
+				if err != nil || !bytes.Equal(original, after) {
+					t.Fatal("isolated task rewrote the ambient index")
+				}
+			}
+			if mode == "ambient_missing" {
+				if _, err := os.Stat(ambient); !os.IsNotExist(err) {
+					t.Fatalf("isolated task created an ambient index: %v", err)
+				}
+			}
+			after, err := os.ReadFile(index)
+			if err != nil || !bytes.Equal(before, after) {
+				t.Fatal("isolated task changed the source index")
+			}
+			out, err := os.ReadFile(filepath.Join(root, "out.txt"))
+			if err != nil || strings.ReplaceAll(string(out), "\r\n", "\n") != "made in isolation\n" {
+				t.Fatalf("applied result = %q %v", out, err)
+			}
+			if rec.landedBeforeApp || rec.childWorktree == "" {
+				t.Fatal("task did not write in its observed worktree before apply")
+			}
+		})
+	}
+}

internal/platform/gitcmd/doc.go

@@ -28,6 +28,9 @@
 // commondir file or a damaged HEAD written afterwards cannot substitute
 // another repository's config. StageAll stages without entering a nested
 // repository, and host-created worktrees are opened as they are added.
+// Ambient index, object-directory and alternate-object-directory overrides are
+// removed before discovery and execution. Trusted callers may explicitly add a
+// private index afterward; repository-declared object alternates still apply.
 //
 // A checkout during `worktree add` runs in a child past the driver listing, so
 // callers add --no-checkout and populate through gitcmd in the new worktree.

internal/platform/gitcmd/gitcmd.go

@@ -188,7 +188,7 @@ func Detached(cmd *exec.Cmd) (cleanup func(), err error) {
 	}
 	env = slices.DeleteFunc(slices.Clone(env), func(kv string) bool {
 		name, _, _ := strings.Cut(strings.ToUpper(kv), "=")
-		return name == "GIT_DIR" || name == "GIT_WORK_TREE" || name == "GIT_COMMON_DIR" || name == "GIT_CEILING_DIRECTORIES"
+		return storageOverride(name) || name == "GIT_DIR" || name == "GIT_WORK_TREE" || name == "GIT_COMMON_DIR" || name == "GIT_CEILING_DIRECTORIES"
 	})
 	cmd.Dir = dir
 	cmd.Env = append(env, "GIT_CEILING_DIRECTORIES="+filepath.Dir(dir))
@@ -230,7 +230,7 @@ func Env() []string {
 		case "GIT_LITERAL_PATHSPECS", "GIT_GLOB_PATHSPECS", "GIT_NOGLOB_PATHSPECS", "GIT_ICASE_PATHSPECS":
 			return true
 		}
-		return false
+		return storageOverride(strings.ToUpper(key))
 	})
 	return append(env,
 		// Read-only probes must not take the index lock.
@@ -243,3 +243,10 @@ func Env() []string {
 		"GIT_NO_LAZY_FETCH=1",
 	)
 }
+
+// storageOverride identifies ambient locations that override a Repo's pinned
+// identity. Trusted host callers can still append an explicit private index or
+// object directory after command construction.
+func storageOverride(name string) bool {
+	return name == "GIT_INDEX_FILE" || name == "GIT_OBJECT_DIRECTORY" || name == "GIT_ALTERNATE_OBJECT_DIRECTORIES"
+}

internal/platform/gitcmd/storage_env_test.go

@@ -0,0 +1,188 @@
+package gitcmd
+
+import (
+	"bytes"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"reasonix/internal/base/testenv"
+)
+
+func storageFixture(t *testing.T, text string) Repo {
+	t.Helper()
+	if _, err := exec.LookPath("git"); err != nil {
+		t.Skip("Git unavailable")
+	}
+	dir := testenv.TempDir(t)
+	if out, err := Command(t.Context(), dir, "init", "-q").CombinedOutput(); err != nil {
+		t.Fatalf("setup: %v %s", err, out)
+	}
+	if err := os.WriteFile(filepath.Join(dir, "file.txt"), []byte(text), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	for _, args := range [][]string{{"add", "file.txt"}, {"commit", "-q", "-m", "fixture"}} {
+		if out, err := CommandWithConfig(t.Context(), dir, []string{"user.name=Fixture", "[email protected]"}, args...).CombinedOutput(); err != nil {
+			t.Fatalf("setup: %v %s", err, out)
+		}
+	}
+	repo, err := Open(t.Context(), dir)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return repo
+}
+
+func TestHostStorageEnvironment(t *testing.T) {
+	for _, key := range []string{"GIT_INDEX_FILE", "GIT_OBJECT_DIRECTORY", "GIT_ALTERNATE_OBJECT_DIRECTORIES"} {
+		t.Run(key, func(t *testing.T) {
+			t.Setenv(key, filepath.Join(t.TempDir(), "ambient"))
+			for _, entry := range Env() {
+				name, _, _ := strings.Cut(entry, "=")
+				if strings.EqualFold(name, key) {
+					t.Fatalf("ambient %s survived", key)
+				}
+			}
+		})
+	}
+}
+
+func TestHostObjectStorage(t *testing.T) {
+	t.Run("writes_stay_in_repository", func(t *testing.T) {
+		repo := storageFixture(t, "source\n")
+		outside := testenv.TempDir(t)
+		t.Setenv("GIT_OBJECT_DIRECTORY", outside)
+		cmd := repo.Command(t.Context(), "hash-object", "-w", "--stdin")
+		cmd.Stdin = strings.NewReader("new host object\n")
+		out, err := cmd.Output()
+		if err != nil {
+			t.Fatal(err)
+		}
+		oid := strings.TrimSpace(string(out))
+		if _, err := os.Stat(filepath.Join(repo.CommonDir, "objects", oid[:2], oid[2:])); err != nil {
+			t.Fatalf("object not in resolved repository: %v", err)
+		}
+		if _, err := os.Stat(filepath.Join(outside, oid[:2], oid[2:])); !os.IsNotExist(err) {
+			t.Fatalf("ambient object directory was written: %v", err)
+		}
+	})
+	t.Run("ambient_alternate_not_read", func(t *testing.T) {
+		repo := storageFixture(t, "source\n")
+		foreign := storageFixture(t, "foreign object\n")
+		out, err := foreign.Command(t.Context(), "rev-parse", "HEAD:file.txt").Output()
+		if err != nil {
+			t.Fatal(err)
+		}
+		oid := strings.TrimSpace(string(out))
+		t.Setenv("GIT_ALTERNATE_OBJECT_DIRECTORIES", filepath.Join(foreign.CommonDir, "objects"))
+		if err := repo.Command(t.Context(), "cat-file", "-e", oid).Run(); err == nil {
+			t.Fatal("host read an object only ambient alternates supplied")
+		}
+	})
+}
+
+func TestHostExplicitStorageControls(t *testing.T) {
+	t.Run("private_index", func(t *testing.T) {
+		repo := storageFixture(t, "before\n")
+		index := filepath.Join(repo.GitDir, "index")
+		before, err := os.ReadFile(index)
+		if err != nil {
+			t.Fatal(err)
+		}
+		ambient := filepath.Join(t.TempDir(), "ambient-index")
+		if err := os.WriteFile(ambient, []byte("not an index"), 0o600); err != nil {
+			t.Fatal(err)
+		}
+		t.Setenv("GIT_INDEX_FILE", ambient)
+		if err := os.WriteFile(filepath.Join(repo.WorkTree, "file.txt"), []byte("after\n"), 0o600); err != nil {
+			t.Fatal(err)
+		}
+		private := filepath.Join(t.TempDir(), "private-index")
+		if err := repo.StageAll(t.Context(), "GIT_INDEX_FILE="+private); err != nil {
+			t.Fatal(err)
+		}
+		cmd := repo.Command(t.Context(), "show", ":file.txt")
+		cmd.Env = append(cmd.Env, "GIT_INDEX_FILE="+private)
+		out, err := cmd.Output()
+		if err != nil || string(out) != "after\n" {
+			t.Fatalf("explicit private index = %q %v", out, err)
+		}
+		after, err := os.ReadFile(index)
+		if err != nil || !bytes.Equal(before, after) {
+			t.Fatal("private staging touched the user's real index")
+		}
+		untouched, err := os.ReadFile(ambient)
+		if err != nil || string(untouched) != "not an index" {
+			t.Fatal("explicit staging changed ambient index")
+		}
+	})
+	t.Run("explicit_object_directory", func(t *testing.T) {
+		repo := storageFixture(t, "source\n")
+		outside := testenv.TempDir(t)
+		t.Setenv("GIT_OBJECT_DIRECTORY", filepath.Join(t.TempDir(), "missing"))
+		cmd := repo.Command(t.Context(), "hash-object", "-w", "--stdin")
+		cmd.Env = append(cmd.Env, "GIT_OBJECT_DIRECTORY="+outside)
+		cmd.Stdin = strings.NewReader("explicit host object\n")
+		out, err := cmd.Output()
+		if err != nil {
+			t.Fatal(err)
+		}
+		oid := strings.TrimSpace(string(out))
+		if _, err := os.Stat(filepath.Join(outside, oid[:2], oid[2:])); err != nil {
+			t.Fatal(err)
+		}
+	})
+	t.Run("repository_declared_alternate", func(t *testing.T) {
+		repo := storageFixture(t, "source\n")
+		foreign := storageFixture(t, "declared alternate\n")
+		out, err := foreign.Command(t.Context(), "rev-parse", "HEAD:file.txt").Output()
+		if err != nil {
+			t.Fatal(err)
+		}
+		path := filepath.Join(repo.CommonDir, "objects", "info", "alternates")
+		if err := os.MkdirAll(filepath.Dir(path), 0o700); err != nil {
+			t.Fatal(err)
+		}
+		if err := os.WriteFile(path, []byte(filepath.ToSlash(filepath.Join(foreign.CommonDir, "objects"))+"\n"), 0o600); err != nil {
+			t.Fatal(err)
+		}
+		if err := repo.Command(t.Context(), "cat-file", "-e", strings.TrimSpace(string(out))).Run(); err != nil {
+			t.Fatalf("declared alternate disabled: %v", err)
+		}
+	})
+}
+
+func TestDetachedStorageEnvironment(t *testing.T) {
+	if _, err := exec.LookPath("git"); err != nil {
+		t.Skip("Git unavailable")
+	}
+	for _, inherited := range []bool{false, true} {
+		t.Run(map[bool]string{false: "explicit_env", true: "inherited_env"}[inherited], func(t *testing.T) {
+			cmd := exec.Command("git", "--version")
+			if inherited {
+				t.Setenv("GIT_INDEX_FILE", "ambient-index")
+				t.Setenv("GIT_OBJECT_DIRECTORY", "ambient-objects")
+				t.Setenv("GIT_ALTERNATE_OBJECT_DIRECTORIES", "ambient-alternates")
+			} else {
+				cmd.Env = append(os.Environ(), "GIT_INDEX_FILE=ambient-index", "GIT_OBJECT_DIRECTORY=ambient-objects", "GIT_ALTERNATE_OBJECT_DIRECTORIES=ambient-alternates")
+			}
+			cleanup, err := Detached(cmd)
+			if err != nil {
+				t.Fatal(err)
+			}
+			defer cleanup()
+			for _, entry := range cmd.Env {
+				name, _, _ := strings.Cut(entry, "=")
+				switch strings.ToUpper(name) {
+				case "GIT_INDEX_FILE", "GIT_OBJECT_DIRECTORY", "GIT_ALTERNATE_OBJECT_DIRECTORIES":
+					t.Fatalf("detached command retained %s", name)
+				}
+			}
+			if out, err := cmd.CombinedOutput(); err != nil {
+				t.Fatalf("detached git: %v %s", err, out)
+			}
+		})
+	}
+}

internal/platform/worktree/storage_env_test.go

@@ -0,0 +1,94 @@
+package worktree
+
+import (
+	"bytes"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"testing"
+
+	"reasonix/internal/base/testenv"
+)
+
+func TestWorktreePreparationOwnsItsIndex(t *testing.T) {
+	for _, kind := range []string{"delivery", "candidate"} {
+		for _, mode := range []string{"ambient_existing", "ambient_missing", "control"} {
+			t.Run(kind+"_"+mode, func(t *testing.T) {
+				requireGit(t)
+				root := initRepo(t)
+				repo := opened(t, root)
+				snap, err := TakeSnapshot(t.Context(), repo)
+				if err != nil {
+					t.Fatal(err)
+				}
+				index := filepath.Join(repo.GitDir, "index")
+				before, err := os.ReadFile(index)
+				if err != nil {
+					t.Fatal(err)
+				}
+				ambient := filepath.Join(testenv.TempDir(t), "ambient-index")
+				var original []byte
+				if mode == "ambient_existing" {
+					writeRepoFile(t, root, "ambient-only.txt", "ambient staged content\n")
+					for _, args := range [][]string{{"read-tree", "HEAD"}, {"add", "ambient-only.txt"}} {
+						cmd := exec.Command("git", append([]string{"-C", root}, args...)...)
+						cmd.Env = append(os.Environ(), "GIT_INDEX_FILE="+ambient)
+						if out, err := cmd.CombinedOutput(); err != nil {
+							t.Fatalf("ambient fixture: %v %s", err, out)
+						}
+					}
+					if err := os.Remove(filepath.Join(root, "ambient-only.txt")); err != nil {
+						t.Fatal(err)
+					}
+					original, err = os.ReadFile(ambient)
+					if err != nil {
+						t.Fatal(err)
+					}
+				}
+				if mode != "control" {
+					t.Setenv("GIT_INDEX_FILE", ambient)
+				}
+				managed := testenv.TempDir(t)
+				var path string
+				if kind == "delivery" {
+					result, err := Create(t.Context(), repo, managed)
+					if err != nil {
+						t.Fatal(err)
+					}
+					path = result.WorktreeRoot
+				} else {
+					candidate, err := CreateCandidate(t.Context(), snap, managed)
+					if err != nil {
+						t.Fatal(err)
+					}
+					path = candidate.WorktreeRoot
+				}
+				if mode == "ambient_existing" {
+					after, err := os.ReadFile(ambient)
+					if err != nil || !bytes.Equal(original, after) {
+						t.Fatal("preparing another worktree rewrote the ambient index")
+					}
+				}
+				if mode == "ambient_missing" {
+					if _, err := os.Stat(ambient); !os.IsNotExist(err) {
+						t.Fatalf("preparation created an ambient index: %v", err)
+					}
+				}
+				after, err := os.ReadFile(index)
+				if err != nil || !bytes.Equal(before, after) {
+					t.Fatal("preparation changed the source index")
+				}
+				child := opened(t, path)
+				if !child.Valid() {
+					t.Fatal("prepared checkout has no own repository identity")
+				}
+				if _, err := os.Stat(filepath.Join(child.GitDir, "index")); err != nil {
+					t.Fatalf("prepared checkout has no own index: %v", err)
+				}
+				if got := readRepoFile(t, path, "README.md"); got != "base\n" {
+					t.Fatalf("checkout bytes=%q", got)
+				}
+			})
+		}
+	}
+}

release-notes/studio/unreleased/14025-git-storage-environment.md

@@ -0,0 +1,2 @@
+- 修复：宿主 Git 的 worktree 准备不再继承外部索引或对象存储变量，保留显式私有索引和仓库备用对象库。关联 #14025。
+- Fixed: host Git worktree preparation drops ambient index and object storage overrides, preserving explicit private indexes and repository alternates. Refs #14025.