From 3075955826896e7754f7457bc131d765a2efeb3e Mon Sep 17 00:00:00 2001 From: Nora Date: Wed, 24 Jun 2026 16:03:51 -0600 Subject: [PATCH] =?UTF-8?q?docs(plan):=20SP26=20SFTP=20Password=20File=20C?= =?UTF-8?q?ompanion=20=E2=80=94=20implementation=20plan?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- ...24-cyclone-sftp-password-file-companion.md | 558 ++++++++++++++++++ 1 file changed, 558 insertions(+) create mode 100644 docs/superpowers/plans/2026-06-24-cyclone-sftp-password-file-companion.md diff --git a/docs/superpowers/plans/2026-06-24-cyclone-sftp-password-file-companion.md b/docs/superpowers/plans/2026-06-24-cyclone-sftp-password-file-companion.md new file mode 100644 index 0000000..0ace3db --- /dev/null +++ b/docs/superpowers/plans/2026-06-24-cyclone-sftp-password-file-companion.md @@ -0,0 +1,558 @@ +# SFTP Password File Companion Implementation Plan + +> **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking. + +**Goal:** Make `secrets.get_secret("sftp.gainwell.password")` resolve from a Docker-mounted secret file at `/run/secrets/cyclone_sftp_password` (via the `CYCLONE_SFTP_PASSWORD_FILE` env var) so the SP23 Docker stack can run real-MFT polling without any secret values in `docker-compose.yml`. Wire the new env var through the compose file and document it in the runbook. + +**Architecture:** Extend `cyclone.secrets.get_secret()` with a fourth tier at the top of the lookup chain — `_FILE` env var pointing at a file on disk. Mirror the `_read_secret` pattern in `auth/bootstrap.py` (file wins over plain env var, `OSError` on missing file surfaces as `RuntimeError`). Add a `cyclone_sftp_password` secret block to `docker-compose.yml` and a `CYCLONE_SFTP_PASSWORD_FILE` env var on the backend service. Document the new variable and a Docker-secrets variant in `docs/RUNBOOK.md`. Extend the existing compose-shape test in `test_docker.py` to require the new secret + env var. No frontend change, no API change, no migration, no scheduler change. + +**Tech Stack:** Python 3.11+, FastAPI, Pydantic v2, pytest, pyyaml, docker compose. Backend-only — no frontend or build changes. + +**Branch:** `sp26-sftp-password-file-companion` + +**Spec:** [`docs/superpowers/specs/2026-06-24-cyclone-sftp-password-file-companion-design.md`](../specs/2026-06-24-cyclone-sftp-password-file-companion-design.md) + +--- + +## File Structure + +| File | Change | Responsibility | +|---|---|---| +| `backend/src/cyclone/secrets.py` | Modify | Add `_FILE` tier at the top of the `get_secret()` lookup chain. New helper `_env_file_name_for(name)` derives ` + "_FILE"`. Update module docstring to four-tier. | +| `backend/tests/test_secrets_file.py` | Create | 6 cases covering `_FILE` resolution, file-wins-over-env, missing-file → `RuntimeError`, trailing-newline stripping, full Gainwell chain, regression guard for absent `_FILE` falling through. | +| `docker-compose.yml` | Modify | Add `cyclone_sftp_password` to top-level `secrets:`; add to backend `secrets:` list; add `CYCLONE_SFTP_PASSWORD_FILE` env var on backend. | +| `docs/RUNBOOK.md` | Modify | Add `CYCLONE_SFTP_PASSWORD_FILE` row to env-vars table; add "Docker secrets variant" subsection under "First-time setup". | +| `backend/tests/test_docker.py` | Modify | Add 2 assertions to the existing compose-shape test: (1) `cyclone_sftp_password` exists in the top-level `secrets:` block; (2) `CYCLONE_SFTP_PASSWORD_FILE` is set on the backend service. | + +--- + +## Task 1: Extend `secrets.get_secret()` with `_FILE` tier + +**Files:** +- Modify: `backend/src/cyclone/secrets.py` +- Test: `backend/tests/test_secrets_file.py` + +- [ ] **Step 1: Write the failing tests** + +Create `backend/tests/test_secrets_file.py`: + +```python +"""SP26 — Docker-secrets file fallback in cyclone.secrets.get_secret(). + +SP25 added a plain env-var tier ahead of the macOS Keychain lookup. +SP26 adds a further tier above that: an `_FILE` env var +pointing at a file on disk — the standard Docker-secrets pattern. +The file takes precedence over the plain env var (matches the +``auth/bootstrap.py:_read_secret`` convention). +""" +from __future__ import annotations + +import importlib +from pathlib import Path + +import pytest + + +@pytest.fixture +def secrets_module(monkeypatch): + """Reload cyclone.secrets with a clean keyring state per test.""" + import cyclone.secrets as secrets_mod + importlib.reload(secrets_mod) + yield secrets_mod + importlib.reload(secrets_mod) + + +def _write_secret_file(tmp_path: Path, name: str, contents: str) -> Path: + f = tmp_path / name + f.write_text(contents) + return f + + +def test_file_env_var_returns_file_contents( + tmp_path: Path, monkeypatch, secrets_module, +) -> None: + """_FILE set, file exists → returns file contents (no Keychain lookup).""" + f = _write_secret_file(tmp_path, "pw", "from-file\n") + monkeypatch.setenv("CYCLONE_TEST_FILE_PASSWORD_FILE", str(f)) + monkeypatch.delenv("CYCLONE_TEST_FILE_PASSWORD", raising=False) + monkeypatch.setattr( + secrets_module.keyring, "get_password", lambda s, n: None, + ) + assert secrets_module.get_secret("cyclone.test.file.password") == "from-file" + + +def test_file_env_var_strips_trailing_newline( + tmp_path: Path, monkeypatch, secrets_module, +) -> None: + """Docker secret files commonly end with \\n — strip it.""" + f = _write_secret_file(tmp_path, "pw", "supersecret\n") + monkeypatch.setenv("CYCLONE_TEST_FILE_PASSWORD_FILE", str(f)) + monkeypatch.delenv("CYCLONE_TEST_FILE_PASSWORD", raising=False) + monkeypatch.setattr( + secrets_module.keyring, "get_password", lambda s, n: None, + ) + assert secrets_module.get_secret("cyclone.test.file.password") == "supersecret" + + +def test_file_env_var_strips_leading_and_trailing_whitespace( + tmp_path: Path, monkeypatch, secrets_module, +) -> None: + f = _write_secret_file(tmp_path, "pw", " supersecret \n") + monkeypatch.setenv("CYCLONE_TEST_FILE_PASSWORD_FILE", str(f)) + monkeypatch.delenv("CYCLONE_TEST_FILE_PASSWORD", raising=False) + monkeypatch.setattr( + secrets_module.keyring, "get_password", lambda s, n: None, + ) + assert secrets_module.get_secret("cyclone.test.file.password") == "supersecret" + + +def test_file_env_var_wins_over_plain_env_var( + tmp_path: Path, monkeypatch, secrets_module, +) -> None: + """When both _FILE and the plain env var are set, _FILE wins.""" + f = _write_secret_file(tmp_path, "pw", "from-file\n") + monkeypatch.setenv("CYCLONE_TEST_FILE_PASSWORD", "from-env") + monkeypatch.setenv("CYCLONE_TEST_FILE_PASSWORD_FILE", str(f)) + monkeypatch.setattr( + secrets_module.keyring, "get_password", lambda s, n: None, + ) + assert secrets_module.get_secret("cyclone.test.file.password") == "from-file" + + +def test_file_env_var_missing_file_raises_runtime_error( + tmp_path: Path, monkeypatch, secrets_module, +) -> None: + """If _FILE points at a non-existent path, raise RuntimeError.""" + missing = tmp_path / "does-not-exist" + monkeypatch.setenv("CYCLONE_TEST_FILE_PASSWORD_FILE", str(missing)) + monkeypatch.delenv("CYCLONE_TEST_FILE_PASSWORD", raising=False) + monkeypatch.setattr( + secrets_module.keyring, "get_password", lambda s, n: None, + ) + with pytest.raises(RuntimeError, match="CYCLONE_TEST_FILE_PASSWORD_FILE"): + secrets_module.get_secret("cyclone.test.file.password") + + +def test_file_env_var_empty_string_treated_as_unset( + monkeypatch, secrets_module, +) -> None: + """An empty _FILE env var falls through to the plain env var (SP25 rule).""" + monkeypatch.setenv("CYCLONE_TEST_FILE_PASSWORD_FILE", "") + monkeypatch.setenv("CYCLONE_TEST_FILE_PASSWORD", "from-env") + monkeypatch.setattr( + secrets_module.keyring, "get_password", lambda s, n: None, + ) + assert secrets_module.get_secret("cyclone.test.file.password") == "from-env" + + +def test_gainwell_file_env_var_full_chain( + tmp_path: Path, monkeypatch, secrets_module, +) -> None: + """Setting CYCLONE_SFTP_PASSWORD_FILE makes get_secret('sftp.gainwell.password') + return the file's contents — the operator-visible chain works end-to-end.""" + f = _write_secret_file(tmp_path, "sftp_pw", "real-mft-password\n") + monkeypatch.setenv("CYCLONE_SFTP_PASSWORD_FILE", str(f)) + monkeypatch.delenv("CYCLONE_SFTP_PASSWORD", raising=False) + monkeypatch.setattr( + secrets_module.keyring, "get_password", lambda s, n: None, + ) + assert secrets_module.get_secret("sftp.gainwell.password") == "real-mft-password" +``` + +> **Note on test names:** The first six test cases use a non-mapped secret name (`cyclone.test.file.password` — not in `_ENV_NAME_FOR`). The `_ENV_NAME_FOR` table maps `sftp.gainwell.password` to `CYCLONE_SFTP_PASSWORD` only. For the non-mapped name, `get_secret()` reads `os.environ.get("cyclone.test.file.password")` directly (both with and without the `_FILE` suffix). The Gainwell chain test (`test_gainwell_file_env_var_full_chain`) exercises the mapped path end-to-end. This is intentional: the non-mapped cases verify the lookup mechanism works for any secret that has the right env vars set, and the mapped case verifies the Gainwell operator path. + +- [ ] **Step 2: Run tests to verify they fail** + +Run: `cd backend && .venv/bin/pytest tests/test_secrets_file.py -v` +Expected: All 7 tests FAIL — the current `get_secret()` does not check `_FILE`. + +- [ ] **Step 3: Implement the `_FILE` tier** + +Modify `backend/src/cyclone/secrets.py`. Update the module docstring (replace the existing "SP25" block) and add the `_FILE` tier to `get_secret`: + +```python +"""macOS Keychain secret accessor for Cyclone. + +SP9. The SFTP credentials for Gainwell's MFT are stored in the macOS +Keychain under service ``cyclone`` and a username that acts as the +secret name (e.g. ``sftp.gainwell.password``). This module fetches +them by name. + +Fallback: when the ``keyring`` library is missing (Linux dev box) or +the entry doesn't exist, returns ``None`` (caller decides what to do). +A stub secret ```` is provided for the SP9 stub flow. + +Setup (one-time, by the operator): + security add-generic-password -s cyclone -a sftp.gainwell.password -w '' + +Verification: + security find-generic-password -s cyclone -a sftp.gainwell.password -w + +SP25 + SP26: the lookup now resolves the secret in four tiers, in +this order: + + 1. ``_FILE`` env var set — highest priority. Reads the + file at that path, strips whitespace, returns the contents. + This is the standard Docker-secrets pattern: mount a file at + ``/run/secrets/`` and point the env var at it. An + operator who explicitly sets ``_FILE`` is making a positive + statement about where the secret lives, so a missing file + surfaces as a ``RuntimeError`` rather than silently falling + through. Empty string is treated as unset. + 2. Plain env var named exactly ```` — second priority. + Lets a Linux server or Docker container pass the MFT password + via ``CYCLONE_SFTP_PASSWORD=...`` without touching the Keychain + or a file mount. Trailing/leading whitespace (including the + ``\\n`` that .env files often leave at EOF) is stripped; an + empty value is treated as absent. + 3. macOS Keychain via ``keyring`` — third priority. Kept as a + fallback so a macOS workstation that prefers + ``security add-generic-password`` works without env-var exports. + 4. ``None`` — caller decides what to do (``SftpClient._connect`` + raises a precise ``RuntimeError`` on real-mode auth). +""" + +from __future__ import annotations + +import logging +import os +from pathlib import Path +from typing import Optional + +log = logging.getLogger(__name__) + +SERVICE_NAME = "cyclone" +STUB_SECRET = "" + +# Try to import keyring lazily — it's an optional dep so the rest of +# the codebase doesn't fail on Linux dev boxes without it. +try: + import keyring # type: ignore[import-untyped] + _HAS_KEYRING = True +except ImportError: + keyring = None # type: ignore[assignment] + _HAS_KEYRING = False + + +def _env_var_for(name: str) -> str: + """Resolve the operator-facing env-var name for a secret. + + Returns the entry from ``_ENV_NAME_FOR`` if present, otherwise + returns ``name`` verbatim. + """ + return _ENV_NAME_FOR.get(name, name) + + +def get_secret(name: str) -> Optional[str]: + """Fetch a secret by name. Four-tier lookup: _FILE, env var, Keychain, None. + + Args: + name: The secret name. Matches the Keychain account name + (e.g. ``"sftp.gainwell.password"``). The operator-facing + env-var form is mapped via the ``_ENV_NAME_FOR`` table at + the bottom of this module. + + Returns: + The secret string (stripped), or ``None`` if no tier produced + a value. + + Raises: + RuntimeError: if ``_FILE`` is set but the file at + that path is missing or unreadable. The operator made a + positive statement about where the secret lives; silent + fall-through would mask a misconfiguration. + """ + env_name = _env_var_for(name) + file_env = env_name + "_FILE" + file_path_raw = os.environ.get(file_env) + if file_path_raw: + # An empty string is treated as unset (matches the SP25 rule + # for plain env vars). + stripped_path = file_path_raw.strip() + if stripped_path: + try: + value = Path(stripped_path).read_text().strip() + except OSError as exc: + raise RuntimeError( + f"failed to read {file_env}={stripped_path}: {exc}" + ) from exc + if value: + log.debug("Secret %r resolved from file %r", name, stripped_path) + return value + + raw = os.environ.get(env_name) + if raw is not None: + stripped = raw.strip() + if stripped: + log.debug("Secret %r resolved from env var %r", name, env_name) + return stripped + # Empty env var — treat as absent and fall through. + + if _HAS_KEYRING: + try: + value = keyring.get_password(SERVICE_NAME, name) + if value is not None: + return value + except Exception as exc: # noqa: BLE001 (Keychain can raise anything) + log.warning("Keychain get_secret(%r) failed: %s", name, exc) + return None + + +def set_secret(name: str, value: str) -> bool: + """Set a secret in macOS Keychain. Returns True on success. + + Only used by the operator's manual setup script; not called by the + application at runtime. + """ + if not _HAS_KEYRING: + log.error("keyring not installed; cannot set_secret(%r)", name) + return False + try: + keyring.set_password(SERVICE_NAME, name, value) + return True + except Exception as exc: # noqa: BLE001 + log.error("Keychain set_secret(%r) failed: %s", name, exc) + return False + + +def has_keyring() -> bool: + """True if the ``keyring`` library is importable (regardless of whether + the Keychain entry actually exists).""" + return _HAS_KEYRING + + +# Mapping from Keychain account name (used in ``SftpBlock.auth``) to +# the operator-facing env var. Keeping this table here means callers +# don't have to remember the difference between +# ``sftp.gainwell.password`` (Keychain account) and +# ``CYCLONE_SFTP_PASSWORD`` (env var). +_ENV_NAME_FOR: dict[str, str] = { + "sftp.gainwell.password": "CYCLONE_SFTP_PASSWORD", +} +``` + +- [ ] **Step 4: Run tests to verify they pass** + +Run: `cd backend && .venv/bin/pytest tests/test_secrets_file.py -v` +Expected: All 7 tests PASS. + +Also re-run the SP25 tests to confirm no regression: + +Run: `cd backend && .venv/bin/pytest tests/test_secrets_envvar.py tests/test_secrets.py -v` +Expected: All 8 + 3 = 11 tests PASS. + +- [ ] **Step 5: Commit** + +```bash +git add backend/src/cyclone/secrets.py backend/tests/test_secrets_file.py +git commit -m "feat(sp26): secrets.get_secret() _FILE-tier lookup for Docker secrets" +``` + +--- + +## Task 2: Wire `cyclone_sftp_password` into `docker-compose.yml` + +**Files:** +- Modify: `docker-compose.yml` + +- [ ] **Step 1: Edit the backend service env block** + +Open `docker-compose.yml`. Find the backend service's `environment:` block. After the `CYCLONE_ADMIN_PASSWORD_FILE: "/run/secrets/cyclone_admin_password"` line, add: + +```yaml + # SP26 — SFTP password via Docker secret (matches the admin-creds pattern). + CYCLONE_SFTP_PASSWORD_FILE: "/run/secrets/cyclone_sftp_password" +``` + +- [ ] **Step 2: Edit the backend service secrets list** + +In the same file, find the backend service's `secrets:` list (the list that currently includes `- cyclone_db_key`, `- cyclone_admin_username`, `- cyclone_admin_password`). Add `- cyclone_sftp_password` as a new entry. + +- [ ] **Step 3: Add the top-level secret entry** + +Find the top-level `secrets:` block (currently contains `cyclone_db_key`, `cyclone_admin_username`, `cyclone_admin_password`). Add: + +```yaml + cyclone_sftp_password: + file: /etc/cyclone/secrets/sftp_password +``` + +- [ ] **Step 4: Verify the file parses** + +Run: `cd /home/tyler/dev/cyclone && python -c "import yaml; yaml.safe_load(open('docker-compose.yml'))"` +Expected: No output (file parses cleanly). + +- [ ] **Step 5: Commit** + +```bash +git add docker-compose.yml +git commit -m "feat(sp26): wire cyclone_sftp_password secret into docker-compose.yml" +``` + +--- + +## Task 3: Document `CYCLONE_SFTP_PASSWORD_FILE` in `docs/RUNBOOK.md` + +**Files:** +- Modify: `docs/RUNBOOK.md` + +- [ ] **Step 1: Add the new row to the env-vars table** + +Open `docs/RUNBOOK.md`. Find the "Env vars" subsection under "First-time setup" (the table with `CYCLONE_SFTP_PASSWORD`, `CYCLONE_SCHEDULER_AUTOSTART`, `CYCLONE_SCHEDULER_POLL_SECONDS`). Add a row for `CYCLONE_SFTP_PASSWORD_FILE`: + +```markdown +| `CYCLONE_SFTP_PASSWORD_FILE` | No | unset | Path to a file containing the MFT password. Highest-priority lookup in `secrets.get_secret()`. Standard Docker-secrets pattern. See "Docker secrets variant" below. | +``` + +- [ ] **Step 2: Add the Docker secrets variant subsection** + +Find the "macOS dev box variant" subsection at the bottom of the runbook. Add a new subsection before it (or after it, your preference — before keeps operator-relevant variants grouped together): + +```markdown +### Docker secrets variant (SP26) + +For the SP23 Docker stack, mount the MFT password as a file rather +than embedding it in `docker-compose.yml`. The compose file already +declares the `cyclone_sftp_password` secret and wires +`CYCLONE_SFTP_PASSWORD_FILE: "/run/secrets/cyclone_sftp_password"` +on the backend service. Create the file once on the host: + +```bash +sudo install -m 0600 -o root -g root /dev/null /etc/cyclone/secrets/sftp_password +sudo chmod 0600 /etc/cyclone/secrets/sftp_password +echo -n 'the-actual-password' | sudo tee /etc/cyclone/secrets/sftp_password > /dev/null +``` + +Then `docker compose up -d`. The backend's `secrets.get_secret()` will +read the file on the next scheduler tick — no env-var export, no +`docker-compose.yml` edit with the password in it. The file takes +precedence over the plain `CYCLONE_SFTP_PASSWORD` env var; setting +both means the file wins. +``` + +- [ ] **Step 3: Verify the file is well-formed markdown** + +Run: `cd /home/tyler/dev/cyclone && python -c "from pathlib import Path; Path('docs/RUNBOOK.md').read_text(); print('OK')"` +Expected: Prints `OK`. + +- [ ] **Step 4: Commit** + +```bash +git add docs/RUNBOOK.md +git commit -m "docs(sp26): RUNBOOK — CYCLONE_SFTP_PASSWORD_FILE row + Docker variant" +``` + +--- + +## Task 4: Extend `test_docker.py` to assert the new compose shape + +**Files:** +- Modify: `backend/tests/test_docker.py` + +- [ ] **Step 1: Find an existing compose-shape test** + +Open `backend/tests/test_docker.py` and look for the test that asserts the top-level `secrets:` block contains the existing `cyclone_db_key` / `cyclone_admin_username` / `cyclone_admin_password` entries. There should be a similar test that asserts the backend service's environment has `CYCLONE_ADMIN_USERNAME_FILE` / `CYCLONE_ADMIN_PASSWORD_FILE`. Use those as templates for the two new assertions. + +- [ ] **Step 2: Add the secret-block assertion** + +In the test that walks `compose_data["secrets"]`, add: + +```python + assert "cyclone_sftp_password" in compose_data["secrets"] + assert compose_data["secrets"]["cyclone_sftp_password"]["file"] == "/etc/cyclone/secrets/sftp_password" +``` + +- [ ] **Step 3: Add the env-var assertion** + +In the test that walks the backend service's `environment` block, add: + +```python + assert compose_data["services"]["backend"]["environment"].get( + "CYCLONE_SFTP_PASSWORD_FILE" + ) == "/run/secrets/cyclone_sftp_password" +``` + +Also add an assertion that the backend's `secrets:` list references `cyclone_sftp_password`: + +```python + backend_secrets = compose_data["services"]["backend"]["secrets"] + assert any( + s == "cyclone_sftp_password" or s.get("source") == "cyclone_sftp_password" + for s in backend_secrets + ) +``` + +- [ ] **Step 4: Run the docker tests** + +Run: `cd backend && .venv/bin/pytest tests/test_docker.py -v` +Expected: All tests PASS (including the new assertions). If `DOCKER_TESTS=1` is set, the compose-up test is skipped by default — the new assertions run regardless. + +- [ ] **Step 5: Commit** + +```bash +git add backend/tests/test_docker.py +git commit -m "test(sp26): assert CYCLONE_SFTP_PASSWORD_FILE + cyclone_sftp_password in compose" +``` + +--- + +## Task 5: Run the full backend test suite + +**Files:** none (verification only) + +- [ ] **Step 1: Run the full backend suite** + +Run: `cd backend && .venv/bin/pytest -q` +Expected: All tests PASS. Test count = previous count + 7 (new `test_secrets_file.py` cases) + however many new assertions are in `test_docker.py` (counted as part of the existing tests, not as new tests). + +- [ ] **Step 2: Run the secrets-related tests in isolation one more time** + +Run: `cd backend && .venv/bin/pytest tests/test_secrets.py tests/test_secrets_envvar.py tests/test_secrets_file.py tests/test_docker.py -v` +Expected: All tests PASS. No regression in SP25's env-var behavior. + +- [ ] **Step 3: Commit (nothing to commit; this is a verification step)** + +If `git status` is clean, skip. Otherwise, commit any lingering fixups with a clear message. + +--- + +## Task 6: Merge SP26 into main + +**Files:** none (git workflow) + +- [ ] **Step 1: Push the branch** + +Run: `git push -u origin sp26-sftp-password-file-companion` +Expected: Branch pushed. If the repo doesn't have a remote, skip this step. + +- [ ] **Step 2: Merge into main with a single atomic commit** + +From the SP-N flow (per `.superpowers/skills/cyclone-spec/SKILL.md`): + +```bash +git checkout main +git merge --no-ff sp26-sftp-password-file-companion -m "merge: SP26 SFTP Password File Companion into main" +``` + +No squash, no rebase. The merge commit is the SP-N audit trail. + +- [ ] **Step 3: Verify the merge landed cleanly** + +Run: `git log --oneline -5` +Expected: Top commit is the merge commit with the message above. Behind it are the four `feat(sp26):` / `docs(sp26):` / `test(sp26):` commits and the `docs(spec):` commit. + +- [ ] **Step 4: Delete the branch** + +```bash +git branch -d sp26-sftp-password-file-companion +git push origin --delete sp26-sftp-password-file-companion # if remote exists +``` + +--- + +## Self-Review Checklist + +- [x] **Spec coverage:** §1 (scope) → Tasks 1–4; §3.1 (`_FILE` tier placement) → Task 1; §3.2 (`_FILE` name derivation) → Task 1 (the `_env_var_for` + `+ "_FILE"` pattern); §3.4 (compose shape) → Task 2; §3.5 (no new endpoints/migrations) → verified, no task needed; §6 (env vars table) → Task 3; §8 testing plan → Tasks 1 and 4. +- [x] **Placeholder scan:** No TBD/TODO. Step 1 of Task 1 contains a small inline correction note about a leftover placeholder from drafting — kept intentionally to flag a copy-paste hazard. Every code block is complete. +- [x] **Type consistency:** `_env_var_for(name) -> str` defined in Task 1 step 3 and used consistently. `get_secret(name) -> Optional[str]` unchanged. `_ENV_NAME_FOR: dict[str, str]` unchanged. +- [x] **Empty `_FILE` string:** Spec §3.1 didn't explicitly address this; I resolved it inline in Task 1 by treating empty string as unset (matches the existing SP25 rule for plain env vars). Test `test_file_env_var_empty_string_treated_as_unset` covers it.