chore(build): prune unclaimed dist/commands/*.md artifacts

[dean0x]

Finding

dist/commands/*.md (compiled command artifacts, output of npm run build:mds) are never pruned when a command host is removed or renamed — stale compiled files can accumulate under dist/commands/.

Why this is tracked

Derived during resolution of PR #334 (not a triaged review finding — a follow-up identified while fixing security-4). security-4 fixed the equivalent stale-artifact exposure for dist/agents/*.md (commit ece15ce): scripts/build-mds.ts now prunes unclaimed dist/agents/*.md using AGENTS_OUTPUT_DIR from the allowlist. dist/commands/ has the same stale-artifact exposure.

Why it's a separate ticket (not folded into security-4's fix)

The claimed set for dist/commands/ is not as simple as "compiled destinations" — it must be compiled destinations ∪ the hand-authored release.md copy (a static, non-MDS command file that also lives in dist/commands/). This makes the prune logic asymmetric with the dist/agents/ case. Exposure is also lower here: there's no competing audited source file that a stale dist/commands/*.md could outrank (unlike the dist/agents/ case where a stale compiled agent could silently shadow a newer hand-authored source).

Suggested fix

Extend the build:mds pruning step (scripts/build-mds.ts) to also prune unclaimed dist/commands/*.md, with the claimed set computed as compiled command destinations unioned with the hand-authored release.md path.

References

• Source review: .devflow/docs/reviews/feat-323-tracker-phase-1-mds-plumbing-provably-by/2026-09-09_2237
• PR: refactor(build): compile the Git agent from an MDS generator host #334
• Origin: security-4 (see Follow-ups section of the resolution summary)
• Related fix: commit ece15ce (dist/agents/ pruning)