Files
my-pi/pi-permission-system/docs/retro/0129-extract-permission-session.md

62 lines
4.3 KiB
Markdown
Raw Permalink Blame History

This file contains ambiguous Unicode characters
This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.
---
issue: 129
issue_title: "refactor: extract PermissionSession class to encapsulate mutable session state"
---
# Retro: #129 — extract PermissionSession class
## Final Retrospective (2026-05-08T02:30:00Z)
### Session summary
Extracted a `PermissionSession` class that encapsulates all mutable session state (`PermissionManager`, `SessionRules`, cache keys, skill entries, runtime context) with operation-based methods replacing field access.
Migrated all 4 handler files and 6 handler test files to use the new class, shrinking `HandlerDeps` from 18 to 7 fields.
Released as v5.10.0 with 38 new unit tests and no behavioral change.
### Observations
#### What went well
- **`SkillPermissionChecker` interface extraction** — the plan didn't anticipate that `resolveSkillPromptEntries` took a concrete `PermissionManager` type.
Rather than using a cast, extracting a narrow `SkillPermissionChecker` interface in `src/skill-prompt-sanitizer.ts` let both `PermissionManager` and `PermissionSession` satisfy it structurally.
This "narrow interface at the callee" pattern avoided adapter objects and should be the default approach for similar migrations.
- **Phase collapse was efficient** — the plan's strict 4-phase separation (build class → wire type → migrate handlers → cleanup) would have required updating every `makeDeps` factory twice.
Collapsing phases 24 into handler-by-handler migration (each handler + its tests in one commit) was cleaner and produced smaller, reviewable diffs.
- **Handler test simplification was dramatic** — `makeSession()` factories went from 7 nested-mock fields with `as unknown as SessionState["permissionManager"]` casts to flat `vi.fn()` stubs.
The `tool-call-events.test.ts` file shrank from 375 to 302 lines while preserving all test cases.
#### What caused friction (agent side)
1. `premature-convergence` — initial `PermissionSession` constructor followed the plan's "4 deps" signature literally (`ExtensionPaths`, `SessionLogger`, `PermissionPrompterApi`, `ForwardingController`), then added `canPrompt()`/`prompt()` methods before realizing the prompting surface doesn't belong on the session (it depends on `ctx` + subagent detection logic the session doesn't own).
Resulted in writing and then deleting ~30 lines of prompting code, plus adding `PermissionSessionRuntimeDeps` as the actual 4th dep.
Impact: ~10 minutes of rework across two edits.
2. `missing-context` — the lifecycle handler rewrite (`src/handlers/lifecycle.ts`) was written from memory rather than referencing the original.
`handleResourcesDiscover` used an undeclared `session` variable and `handleSessionShutdown` called a non-existent `session.clearStatus()` method.
Caught immediately on the next read, but the file had to be rewritten.
Impact: one extra write cycle, no commit waste.
3. `missing-context``vi.mock` paths in the initial test file used `./src/` instead of `../src/`.
Tests run from `tests/`, so the relative paths were wrong.
Caught on first test run.
Impact: one extra edit, no rework.
4. `missing-context` — test mocks used shorthand `SkillPromptEntry` shapes like `{ name: "s", path: "/s", content: "c" }` that passed Vitest (esbuild, no type checking) but failed `tsc`.
The real type has 6 required fields (`name`, `description`, `location`, `state`, `normalizedLocation`, `normalizedBaseDir`).
Fixed by adding a `makeSkillEntry()` helper.
Impact: one extra commit fixup at the end, but could have been avoided by checking the `SkillPromptEntry` type before writing mock data.
5. `wrong-abstraction` — the plan proposed `PermissionSession` absorb `canPrompt(ctx)` and `prompt(ctx, details)`, but these methods require `isSubagentExecutionContext()` and `canResolveAskPermissionRequest()` which depend on `subagentSessionsDir` and config — concerns the session shouldn't own.
The correct boundary keeps prompting on `HandlerDeps` until #130 handler classes can own the `ctx`-capture pattern.
Impact: plan deviation documented in the summary, no code waste beyond friction point #1.
#### What caused friction (user side)
- No friction observed.
The user ran `/plan-issue`, `/tdd-plan`, and `/ship-issue` in sequence with no mid-session corrections needed.
The autoformat hooks ran cleanly throughout.
### Changes made
1. Created `docs/retro/0129-extract-permission-session.md` (this file).