my-pi/pi-permission-system/docs/retro/0057-replace-session-approval-cache-with-session-rules.md

issue, issue_title

issue	issue_title
57	Replace SessionApprovalCache with session Ruleset

Retro: #57 — Replace SessionApprovalCache with session Ruleset

Final Retrospective (2026-05-03T21:10:00-04:00)

Session summary

Replaced SessionApprovalCache (directory-prefix matching via isPathWithinDirectory()) with SessionRules (a plain Ruleset evaluated via evaluate() / wildcardMatch()). Five commits landed matching the five TDD steps in the plan, plus the docs commit. Released as v3.10.0 with no user-visible behavior change. This unblocks #51 (generalize session approvals to all permission surfaces).

Observations

What went well

• The plan-to-implementation mapping was 1:1 — every TDD step produced exactly one commit with the suggested message.
• The wildcard semantics concern (sibling directory false positive) was validated immediately by the session-rules.test.ts integration tests. wildcardMatch("/other/project/*", "/other/project-b/foo.ts") correctly returns false because the regex is anchored.
• The evaluate() integration approach (checking sessionRuleset.includes(sessionMatch) to distinguish a real match from a synthetic default) was clean and required no special-casing.

What caused friction (agent side)

1. missing-context — The plan identified tests/handlers/lifecycle.test.ts and tests/handlers/tool-call.test.ts as the test files needing mock updates, but missed tests/handlers/before-agent-start.test.ts and tests/handlers/input.test.ts, which also construct makeRuntime() helpers with sessionApprovalCache. Vitest (esbuild) does not typecheck, so the stale mocks compiled and ran without error. The mismatch was only caught by npm run build (tsc) during the final verification step. Impact: required amending the "remove SessionApprovalCache" commit to include two additional test file updates. Self-identified during the tsc step.

What caused friction (user side)

• No friction observed — the session required no user intervention beyond the standard autoformat hooks.