feat: allow relative target paths for git mounts

- Remove absolute path requirement from target_path validation
- Resolve relative paths against working_directory at instance startup
- Fall back to /home/user if no working_directory is configured
- Update frontend to allow relative target paths
- Update spec to document relative path support
- Update tests to allow relative paths and test path traversal rejection

apps/api/src/api/config_profiles.py

@@ -82,8 +82,6 @@ class GitMountItem(BaseModel):
     @field_validator("target_path")
     @classmethod
     def validate_target_path(cls, v: str) -> str:
-        if not v.startswith("/"):
-            raise ValueError("target_path must be absolute (start with /)")
         if ".." in v:
             raise ValueError("target_path cannot contain path traversal (..)")
         return v

apps/api/src/api/tool_instances.py

@@ -61,6 +61,7 @@ async def _resolve_git_mounts(
     session: AsyncSession,
     resolved: ResolvedProfile,
     instance_dir: str | None = None,
+    working_directory: str | None = None,
 ) -> list[dict]:
     """Convert git mounts from resolved profile to Docker volume mounts.
     
@@ -74,7 +75,7 @@ async def _resolve_git_mounts(
     # Process all git mounts concurrently
     tasks = []
     for git_mount in resolved.git_mounts:
-        tasks.append(_resolve_single_git_mount(session, git_mount, instance_dir))
+        tasks.append(_resolve_single_git_mount(session, git_mount, instance_dir, working_directory))
     
     results = await asyncio.gather(*tasks, return_exceptions=True)
     
@@ -93,6 +94,7 @@ async def _resolve_single_git_mount(
     session: AsyncSession,
     git_mount: dict,
     instance_dir: str | None = None,
+    working_directory: str | None = None,
 ) -> list[dict]:
     """Resolve a single git mount to volume mount entries.
     
@@ -108,6 +110,12 @@ async def _resolve_single_git_mount(
         logger.warning("Invalid git mount skipped: missing remote_url or target_path")
         return []
     
+    # Resolve relative target paths against working directory
+    if target_path and not target_path.startswith("/"):
+        base = working_directory or "/home/user"
+        target_path = os.path.join(base, target_path)
+        logger.info("Resolved relative target path to %s", target_path)
+    
     if not instance_dir:
         logger.warning("Git mount skipped: no instance_dir provided for cloning")
         return []
@@ -918,7 +926,7 @@ async def start_instance(
             # Profile mounts are added to extra volumes
             extra_volumes.extend(profile_mounts)
             # Git repository mounts are resolved and added
-            git_mount_volumes = await _resolve_git_mounts(session, resolved, instance_dir)
+            git_mount_volumes = await _resolve_git_mounts(session, resolved, instance_dir, working_directory)
             extra_volumes.extend(git_mount_volumes)
             # Profile runtime hints override tool config values
             if profile_hints.get("start_command"):

apps/api/tests/integration/test_config_profiles_api.py

@@ -402,8 +402,8 @@ class TestConfigProfilesAPI:
         )
         assert response.status_code == 422
 
-    def test_create_config_profile_invalid_git_mount_target_path(self, authenticated_client: TestClient, test_project_and_repo) -> None:
+    def test_create_config_profile_invalid_git_mount_target_path_traversal(self, authenticated_client: TestClient, test_project_and_repo) -> None:
-        """Test that invalid git mount target paths are rejected."""
+        """Test that git mount target paths with traversal are rejected."""
         _project_id, repo_id = test_project_and_repo
 
         response = authenticated_client.post(
@@ -416,7 +416,7 @@ class TestConfigProfilesAPI:
                     {
                         "remote_url": "https://github.com/user/repo.git",
                         "source_path": ".",
-                        "target_path": "relative/path",
+                        "target_path": "../../../etc/passwd",
                     }
                 ],
             },

apps/web/src/components/git-mount-editor.tsx

@@ -36,7 +36,6 @@ export const GitMountEditor = ({ mounts, onChange }: GitMountEditorProps) => {
   const validatePath = (path: string, isTarget: boolean): string | null => {
     if (!path) return isTarget ? "Target path is required" : null;
     if (path.includes("..")) return "Path cannot contain ..";
-    if (isTarget && !path.startsWith("/")) return "Target path must be absolute";
     if (!isTarget && path.startsWith("/")) return "Source path must be relative";
     return null;
   };
@@ -200,7 +199,7 @@ const GitMountForm = ({ mount, onSave, onCancel, validatePath, validateUrl, isNe
           placeholder="e.g., /app/config"
           className={errors.target_path ? "error" : ""}
         />
-        <span className="hint">Absolute path inside container</span>
+        <span className="hint">Absolute or relative path inside container (relative resolved against working dir)</span>
         {errors.target_path && <span className="error-text">{errors.target_path}</span>}
       </div>
 

openspec/changes/config-profile-git-mounts/specs/config-profile-git-mounts/spec.md

@@ -16,7 +16,7 @@ The system SHALL allow config profiles to include git repository mounts that bin
 - **THEN** the system validates that:
   - `remote_url` is a valid git URL (starts with https://, git@, or ssh://)
   - `source_path` is a relative path (no leading `/`)
-  - `target_path` is an absolute path (starts with `/`)
+  - `target_path` can be absolute (starts with `/`) or relative (resolved against working directory, defaulting to `/home/user`)
   - `target_path` does not contain path traversal sequences (`..`)
   - No database lookup or repository existence check is performed (validation is deferred to clone time)