# Refactor Changelog — Input/Output Unification + Presenter + Error Middleware + Public-Surface Cleanup

**Started:** 2026-05-06
**Spec:** [2026-05-06-input-output-unification-design.md](../specs/2026-05-06-input-output-unification-design.md)
**Plan:** [2026-05-06-plan-9-io-unification.md](../plans/2026-05-06-plan-9-io-unification.md)
**Branch:** feature/io-unification

This document captures every architectural change made during Plan 9
execution, organized by category. After the plan is merged, use the
"Doc update checklist" at the bottom to update external docs in a
single follow-up pass — combined with the still-pending Plan 8
doc-update items so docs are written once for the post-Plan-9 state.

---

## 1. Files added

(populated as work progresses)

## 2. Files modified

(populated as work progresses)

## 3. Pattern changes (code-level)

### 3.1 Use-case files — input + output schemas + runtime parse
(populated when use cases are migrated)

### 3.2 Controller files — presenter + unknown input + view return type
(populated when controllers are migrated)

### 3.3 tRPC integration — feature-scoped procedures, schema reuse from use cases
(populated when routers are migrated)

## 4. Error-middleware adoption

(populated when defineErrorMiddleware is wired in core-shared and consumed by features)

## 5. Public-API surface

### 5.1 ./ui subpath added per feature
(populated as features adopt the subpath)

### 5.2 Feature root index.ts cleanup
(populated as features clean up their root exports)

## 6. Test additions

### 6.1 R25 — output-validation tests (use case)
(populated when use cases gain malformed-input "repo lied" tests)

### 6.2 R26 — router error-mapping tests
(populated when feature routers gain TRPCError-translation tests)

### 6.3 R27/R28 — presenter shape tests
(populated when controllers with non-identity presenters add view-shape assertions)

## 7. Open issues / deferred decisions

(populated as encountered)

---

## Doc update checklist (deferred — combined with paused Plan 8 doc pass)

After Plan 9 lands, the still-pending Plan 8 doc-update items resume
and now also pick up Plan 9 rules. Each item below covers BOTH plans'
material so we touch every file once.

- [ ] `CLAUDE.md` — Key Conventions: append schema-in-use-case rule, presenter rule, controller `unknown` input rule, `./ui` subpath rule, schema-export-from-root rule
- [ ] `AGENTS.md` (root) — Per-Package Conventions: document `./ui` subpath, schema reachability from feature root, factory-bound use cases / controllers (carry-over from Plan 8)
- [ ] `docs/guides/adding-a-feature.md` — restructure to use the Plan-9 use-case template (with input + output schemas + parse), the Plan-9 controller template (with presenter), and the new `procedures.ts` step (per-feature error map)
- [ ] `docs/guides/tdd-workflow.md` — update mock decision tree + worked example to factory injection (Plan 8) + R25 output-validation test pattern (Plan 9) + R26 router-error-mapping test pattern (Plan 9)
- [ ] `docs/guides/testing-strategy.md` — Mocking section: direct factory injection (Plan 8); R25/R26/R27/R28 test obligations (Plan 9)
- [ ] `docs/architecture/vertical-feature-spec.md` — §6 file shape: schemas + presenter + procedures.ts; §10 testing: R25/R26/R27/R28
- [ ] `docs/architecture/overview.md` — data-flow box: add input schema, output schema, presenter, error-middleware lanes
- [ ] `docs/architecture/dependency-flow.md` — verify (no expected change beyond a `./ui` mention)
- [ ] `docs/decisions/adr-012-lazar-conformance.md` — append note that input/output unification + presenter + error middleware land in ADR-013
- [ ] `docs/decisions/adr-013-input-output-unification.md` — created in this plan's final task (Task 9); link from prior ADRs
- [ ] Per-feature `AGENTS.md` (auth/blog/media/marketing-pages/navigation) — Plan 8 file paths + Plan 9 schema/presenter/procedures patterns
- [ ] `packages/core-testing/AGENTS.md` — note R25/R26 test patterns
- [ ] `packages/core-shared/AGENTS.md` — document `defineErrorMiddleware` and the `t` re-export
- [ ] Plan 8 plan/spec — add a one-line annotation that some controller/router patterns shifted in Plan 9; link to this changelog

---

## Notes for the doc-update pass author

When updating external docs, apply these substitutions globally:

| Old reference | New reference |
|---|---|
| Use case takes `{ x }` directly typed | Use case takes `XInput` (`z.infer<typeof xInputSchema>`); schema lives in same file |
| Use case returns `Promise<Entity>` | Use case returns `Promise<XOutput>` validated by `xOutputSchema.parse(...)` |
| Controller imports `z` and defines local `inputSchema` | Controller imports `xInputSchema` from the use-case file |
| Controller input typed `Partial<z.infer<...>>` | Controller input typed `unknown` |
| Controller returns `Promise<Entity>` | Controller has `function presenter(value: XOutput)`; returns `Promise<ReturnType<typeof presenter>>` (or `Promise<void>` for void use cases) |
| Router uses `publicProcedure` from `core-shared/trpc/init` | Router uses feature's `xProcedure` from `./procedures` |
| Router redefines input schema as `z.object({...})` in `.input(...)` | Router uses `.input(xInputSchema)` imported from the use-case file |
| Domain error reaches the wire as a generic `TRPCError({ code: "INTERNAL_SERVER_ERROR" })` | Domain error mapped to specific code by `defineErrorMiddleware` in `procedures.ts` |
| Frontend imports `articleBySlugQuery` from `@repo/blog` | Frontend imports from `@repo/blog/ui` |