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msd-core/.changeset/3589-planning-paths-workstream-validation.md
Tom Boucher a2967bfa24 fix(3589)(security): validate workstream in relPlanningPath against traversal
`relPlanningPath(workstream)` previously called `posix.join('.planning',
'workstreams', workstream)` without validating the workstream argument.
Direct SDK callers — and `planningPaths` / `ContextEngine` which both
forward through `relPlanningPath` — could pass values like
`'../../../outside'`, `'foo/bar'`, or `'foo\\bar'` and route planning
operations outside the intended `.planning/workstreams/<name>` subtree.

The env-sourced workstream code path in `planningPaths` already validated
via `validateWorkstreamName` (line 444-445, pre-filtering to `null` on
failure per the #2791 silent-fallback contract). Explicit SDK arguments
had no equivalent gate.

Fix: validate inside `relPlanningPath` using the same shared
`validateWorkstreamName` policy. Every caller — direct SDK use,
`planningPaths`, `ContextEngine` — fails closed at the same seam.
Empty/undefined workstream still returns `.planning` for back-compat
(treated as "no workstream provided"); non-empty invalid names throw a
synchronous Error with the offending value in the message.

Env-sourced behaviour is unchanged: `planningPaths` continues to filter
invalid env values to `null` before they reach `relPlanningPath`, so the
silent-fallback path for malformed `GSD_WORKSTREAM` env still works.

Regression test
(sdk/src/bug-3589-planning-paths-validation.test.ts):

  - 9 traversal/invalid cases (.., /, \\, spaces, .hidden, /abs,
    -leading-hyphen) all throw with a `/workstream/i`-matching message.
  - Valid names (`frontend`, `api_v2`, `alpha.beta-1`) continue to
    produce the expected `.planning/workstreams/<name>` path.
  - `planningPaths('/tmp', '../../../outside')` rejects before path
    construction (proven via try/catch — resultPath stays null).
  - Valid workstream + `planningPaths` produces the expected subtree
    (`.planning/workstreams/frontend/STATE.md` etc.).
  - Omitted workstream still returns root `.planning` with no `workstreams`
    segment.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-15 22:52:14 -04:00

6 lines
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Markdown

---
type: Security
issue: 3589
---
**`relPlanningPath()` now validates explicit workstream names** — direct SDK callers passing a workstream argument to `relPlanningPath`, `planningPaths`, or `ContextEngine` previously had no path-traversal gate. A value like `'../../../outside'` flowed through `posix.join('.planning', 'workstreams', name)` and routed planning operations outside the intended `.planning/workstreams/<name>` subtree. The fix runs the shared `validateWorkstreamName` policy inside `relPlanningPath` so every consumer fails closed at the same seam. Env-sourced workstreams continue to fall back silently to root `.planning/` per the #2791 contract (they are filtered to `null` by `planningPaths` before reaching `relPlanningPath`).