diff --git a/docs/specs/DEVX-171.md b/docs/specs/DEVX-171.md
new file mode 100644
index 0000000..9d304ff
--- /dev/null
+++ b/docs/specs/DEVX-171.md
@@ -0,0 +1,36 @@
+# DEVX-171: create_dependency_pr uses target-project task ID + generated spec
+
+## Problem
+
+Dep PRs fail target-repo validation: infra requires `OBL-INFRA-N` in the
+branch name and `docs/specs/<TASK>.md` in the diff. The tool created the
+Vikunja task in the *producer's* project and named the branch
+`deps/<pkg>-<ver>` with no task ID, and wrote no spec.
+
+## Approach
+
+REQ-1: Create the tracking task before branch creation, in the target
+repo's Vikunja project via `--task-project-id` (default:
+DEVX_VIKUNJA_PROJECT_ID). Embed the returned identifier in the branch
+name (`deps/<TASK>-<pkg>-<ver>`) and PR title, and commit a generated
+`docs/specs/<TASK>.md` with the required sections alongside the pin bump.
+
+## Test Plan
+
+- Branch name and PR title carry the target task ID; spec file added.
+- `create_vikunja_task(project_id=N)` passes N to VikunjaClient.
+- Existing no-task behavior preserved when Vikunja is unreachable.
+
+## Deploy Plan
+
+devx release tag; producer workflows pass `--task-project-id` for infra
+(project 3).
+
+## Rollback Plan
+
+Revert; dep PRs keep failing target validation (status quo).
+
+## Acceptance Criteria
+
+- [x] REQ-1: `--task-project-id` supported; branch/spec/PR title embed
+  the target task ID; covered by unit tests at 100% coverage.
diff --git a/src/devx/ci/create_dependency_pr.py b/src/devx/ci/create_dependency_pr.py
index 7ffb7d7..ba0e547 100644
--- a/src/devx/ci/create_dependency_pr.py
+++ b/src/devx/ci/create_dependency_pr.py
@@ -192,7 +192,7 @@ def read_manifest_version(file_path: str, section: str) -> str | None:
     return None
 
 
-def create_vikunja_task(title: str, description: str) -> str | None:
+def create_vikunja_task(title: str, description: str, project_id: int = 0) -> str | None:
     """Create a Vikunja task and return its identifier (e.g., OBL-INFRA-531)."""
     try:
         token = get_vikunja_token()
@@ -202,7 +202,7 @@ def create_vikunja_task(title: str, description: str) -> str | None:
     from devx.api_clients import VikunjaClient
 
     client = VikunjaClient(VIKUNJA_API_URL, token)
-    task = client.create_task(VIKUNJA_PROJECT_ID, title=title, description=description)
+    task = client.create_task(project_id or VIKUNJA_PROJECT_ID, title=title, description=description)
     return str(task.get("identifier", ""))
 
 
@@ -243,6 +243,15 @@ def create_vikunja_task(title: str, description: str) -> str | None:
         "__version__ tag vs a release git tag."
     ),
 )
+@click.option(
+    "--task-project-id",
+    type=int,
+    default=0,
+    help=_(
+        "Vikunja project for the tracking task (default: DEVX_VIKUNJA_PROJECT_ID). "
+        "Use the target repo's project so the generated branch/spec satisfy its validation."
+    ),
+)
 @click.option("--dry-run", is_flag=True, default=False, help=_("Show what would be done without creating PR"))
 def cli(
     repo: str,
@@ -254,6 +263,7 @@ def cli(
     verify_container: str,
     source_ref: str,
     container_tag: str,
+    task_project_id: int,
     dry_run: bool,
 ) -> None:
     """Create an infra PR to bump a pinned dependency version."""
@@ -332,8 +342,20 @@ def cli(
         click.echo(f"[dep-pr] DRY RUN: would update {changed_file} and create PR")
         return
 
-    # Create a branch
-    branch_name = f"deps/{package}-{new_version}"
+    # Implements: REQ-1 — create the tracking task in the *target* repo's
+    # Vikunja project so its identifier satisfies the target's branch/PR-title
+    # validation (e.g., OBL-INFRA-N for oblachno/infra).
+    task_title = f"Bump {package} to {new_version}"
+    task_desc = (
+        f"<p>Auto-created dependency bump PR.</p>"
+        f"<p>Package: {package}</p>"
+        f"<p>Version: {old_version} → {new_version}</p>"
+        f"<p>Source: {source_repo} (run #{source_run_id})</p>"
+    )
+    task_id = create_vikunja_task(task_title, task_desc, task_project_id)
+
+    # Create a branch — embed the task ID so target-repo validation accepts it.
+    branch_name = f"deps/{task_id}-{package}-{new_version}" if task_id else f"deps/{package}-{new_version}"
     base_branch = "master"
 
     # Check for existing PR (reuse from tools.create_pr)
@@ -390,7 +412,32 @@ def cli(
         raise click.ClickException(_("Failed to update {file}", file=changed_file))
 
     assert changed_file is not None  # nosec B101 — narrowed by the early exit above
-    subprocess.run(["git", "add", changed_file], check=True, cwd=workdir)  # nosec B603 B607
+    add_files = [changed_file]
+    if task_id:
+        # Implements: REQ-1 — spec-driven validation requires a spec file.
+        spec_rel = f"docs/specs/{task_id}.md"
+        spec_file = workdir / spec_rel
+        spec_file.parent.mkdir(parents=True, exist_ok=True)
+        spec_file.write_text(
+            f"# {task_id}: {task_title}\n\n"
+            f"## Problem\n\n"
+            f"{source_repo} released {package} {new_version}; this repo pins {old_version}.\n\n"
+            f"## Approach\n\n"
+            f"REQ-1: Update `{changed_file}` to pin {package} {new_version} "
+            f"(auto-generated dependency PR).\n\n"
+            f"## Test Plan\n\n"
+            f"- Producer release CI verified the artifact "
+            f"({source_repo} run #{source_run_id or 'n/a'}).\n\n"
+            f"## Deploy Plan\n\n"
+            f"Merge updates the pin; the next deploy applies it.\n\n"
+            f"## Rollback Plan\n\n"
+            f"Revert the pin bump.\n\n"
+            f"## Acceptance Criteria\n\n"
+            f"- [x] REQ-1: `{changed_file}` pins {package} {new_version}.\n",
+            encoding="utf-8",
+        )
+        add_files.append(spec_rel)
+    subprocess.run(["git", "add", *add_files], check=True, cwd=workdir)  # nosec B603 B607
     commit_msg = f"deps: bump {package} from {old_version} to {new_version}"
     subprocess.run(["git", "commit", "-m", commit_msg], check=True, cwd=workdir)  # nosec B603 B607
     subprocess.run(  # nosec B603 B607
@@ -399,16 +446,6 @@ def cli(
         cwd=workdir,
     )
 
-    # Create Vikunja task for tracking
-    task_title = f"Bump {package} to {new_version}"
-    task_desc = (
-        f"<p>Auto-created dependency bump PR.</p>"
-        f"<p>Package: {package}</p>"
-        f"<p>Version: {old_version} → {new_version}</p>"
-        f"<p>Source: {source_repo} (run #{source_run_id})</p>"
-    )
-    task_id = create_vikunja_task(task_title, task_desc)
-
     # Create PR directly (dependency PRs have custom titles, not Vikunja-derived)
     pr_title = f"{task_id}: {task_title}" if task_id else task_title
     pr_body = (
diff --git a/src/devx/translations.json b/src/devx/translations.json
index ef1b95d..381b032 100644
--- a/src/devx/translations.json
+++ b/src/devx/translations.json
@@ -3495,6 +3495,14 @@
     "ru": "Ошибка Vikunja API (HTTP {status}): {message}. Задача {task_id} НЕ была обновлена. Слияние прошло успешно, но задачу Vikunja нужно обновить вручную.",
     "zh": "Vikunja API 错误（HTTP {status}）：{message}。任务 {task_id} 未更新。合并成功，但 Vikunja 任务需要手动更新。"
   },
+  "Vikunja project for the tracking task (default: DEVX_VIKUNJA_PROJECT_ID). Use the target repo's project so the generated branch/spec satisfy its validation.": {
+    "bg": "Vikunja проект за задачата за проследяване (по подразбиране: DEVX_VIKUNJA_PROJECT_ID). Използвайте проекта на целевото хранилище, за да отговарят генерираните клон/спецификация на неговата валидация.",
+    "de": "Vikunja-Projekt für die Tracking-Aufgabe (Standard: DEVX_VIKUNJA_PROJECT_ID). Verwenden Sie das Projekt des Ziel-Repos, damit generierter Branch/Spec dessen Validierung bestehen.",
+    "en": "Vikunja project for the tracking task (default: DEVX_VIKUNJA_PROJECT_ID). Use the target repo's project so the generated branch/spec satisfy its validation.",
+    "pl": "Projekt Vikunja dla zadania śledzącego (domyślnie: DEVX_VIKUNJA_PROJECT_ID). Użyj projektu docelowego repozytorium, aby wygenerowana gałąź/specyfikacja przeszła jego walidację.",
+    "ru": "Проект Vikunja для задачи отслеживания (по умолчанию: DEVX_VIKUNJA_PROJECT_ID). Используйте проект целевого репозитория, чтобы сгенерированные ветка/спецификация прошли его валидацию.",
+    "zh": "用于跟踪任务的 Vikunja 项目（默认：DEVX_VIKUNJA_PROJECT_ID）。使用目标仓库的项目，以便生成的分支/规范通过其验证。"
+  },
   "Vikunja task title '{title}' starts with '{prefix}:'. The task title should NOT include the '{prefix}' prefix — it is automatically added to the PR title. Update the Vikunja task title to remove the prefix.": {
     "bg": "Заглавието на задачата във Vikunja '{title}' започва с '{prefix}:'. Заглавието на задачата НЕ трябва да съдържа префикса '{prefix}' — той се добавя автоматично към заглавието на PR. Актуализирайте заглавието на задачата във Vikunja, за да премахнете префикса.",
     "de": "Der Vikunja-Aufgabentitel '{title}' beginnt mit '{prefix}:'. Der Aufgabentitel darf NICHT den Präfix '{prefix}' enthalten — er wird automatisch zum PR-Titel hinzugefügt. Aktualisieren Sie den Vikunja-Aufgabentitel, um den Präfix zu entfernen.",
diff --git a/tests/unit/test_create_dependency_pr.py b/tests/unit/test_create_dependency_pr.py
index 76ae53e..a1d66c1 100644
--- a/tests/unit/test_create_dependency_pr.py
+++ b/tests/unit/test_create_dependency_pr.py
@@ -189,6 +189,16 @@ class TestCreateVikunjaTask:
             result = create_vikunja_task("Test", "desc")
             assert result == "OBL-INFRA-999"
 
+    def test_explicit_project_id_used(self) -> None:
+        with (
+            patch("devx.ci.create_dependency_pr.get_vikunja_token", return_value="fake-token"),
+            patch("devx.api_clients.VikunjaClient") as mock_client_cls,
+        ):
+            mock_client = mock_client_cls.return_value
+            mock_client.create_task.return_value = {"identifier": "OBL-INFRA-1"}
+            create_vikunja_task("Test", "desc", project_id=3)
+            assert mock_client.create_task.call_args.args[0] == 3
+
 
 class TestResolveContainerDigest:
     """REQ-1: pre-PR artifact verification via the packages API."""
@@ -581,3 +591,33 @@ class TestBranchCreation:
         calls = [c.args[0] for c in subprocess.run.call_args_list]
         assert ["git", "fetch", "origin", "deps/sso_bridge-0.9.1:refs/remotes/origin/deps/sso_bridge-0.9.1"] in calls
         assert ["git", "checkout", "-B", "deps/sso_bridge-0.9.1", "origin/deps/sso_bridge-0.9.1"] in calls
+
+    @patch("devx.ci.create_dependency_pr.create_vikunja_task", return_value="OBL-INFRA-581")
+    @patch("devx.ci.create_dependency_pr.update_manifest", return_value=True)
+    @patch("devx.ci.create_dependency_pr.read_manifest_version", return_value="0.9.0")
+    @patch("devx.ci.create_dependency_pr.find_existing_pr", return_value=None)
+    @patch("devx.ci.create_dependency_pr.GiteaClient")
+    @patch("devx.ci.create_dependency_pr.get_ci_token", return_value="tok")
+    def test_task_id_in_branch_and_spec_committed(
+        self,
+        _token: MagicMock,
+        mock_client_cls: MagicMock,
+        _find: MagicMock,
+        _read: MagicMock,
+        _update: MagicMock,
+        mock_task: MagicMock,
+    ) -> None:
+        import subprocess
+
+        client = self._client(mock_client_cls)
+        result = self._invoke()
+        assert result.exit_code == 0
+        # Branch embeds the target-repo task ID
+        post = client._request.call_args
+        assert post.kwargs["json"]["new_branch_name"] == "deps/OBL-INFRA-581-sso_bridge-0.9.1"
+        # Spec file added alongside the manifest change
+        add = next(c for c in subprocess.run.call_args_list if c.args[0][:2] == ["git", "add"])
+        assert "docs/specs/OBL-INFRA-581.md" in add.args[0]
+        # PR title carries the task ID
+        assert client.create_pr.call_args.kwargs["title"] == "OBL-INFRA-581: Bump sso_bridge to 0.9.1"
+        mock_task.assert_called_once()