docs(plans): plan for #230 smart-input week-boundary and 2-letter aliases

#230

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: pajoma

docs/plans/2026-06-01-fix-230-smart-input-week-and-weekday-aliases.md

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+# Plan — Issue #230: Smart input week-text boundary and 2-letter weekday aliases
+
+> **Spec:** [docs/specs/2026-06-01-fix-230-smart-input-week-and-weekday-aliases.md](../specs/2026-06-01-fix-230-smart-input-week-and-weekday-aliases.md)
+> **Issue:** [pajoma/vscode-journal#230](https://github.com/pajoma/vscode-journal/issues/230)
+> **Branch:** `feat/177-smart-input-tokenizer` (implemented alongside #177)
+> **Created:** 2026-06-01
+
+## Approach
+
+Both bugs are addressed in the #177 tokenizer branch. Bug 1 is already resolved by the tokenizer's architecture — `recognizeWeek` uses `(?=\s|$)` as a zero-width lookahead so no character is consumed from the following text. Bug 2 requires adding `mo`, `tu`, `we`, `th` to `weekdayVocab()` (plus `fr` is already covered by the German section). `getDayOfWeekForString` in `dates.ts` already maps all five 2-letter forms correctly; only the vocab recognizer needs updating.
+
+**Trade-off:** `we` and `th` are common English words; adding them as standalone weekday tokens introduces the same ambiguity class as German `di`/`do`. This is accepted per spec: the tokenizer marks them `ambiguous` (≤3 chars), which triggers the yellow border feedback in the QuickPick.
+
+## Steps
+
+1. **Verify Bug 1 is resolved** — add regression test: `parseInput("task week Finalize Shoppinglist")` → `flags="task"`, `text="Finalize Shoppinglist"`, `hasWeek()=true`. No code change needed.
+
+2. **Add 2-letter English aliases to `weekdayVocab()`** — append `'mo', 'tu', 'we', 'th', 'fr'` after the 3-letter English block (`mon/tue/wed/thu/fri/sat/sun`). Longest-first ordering preserved (3-letter tried before 2-letter). `fr` already present in German section; adding it to English section makes intent explicit and matches first (same result from `getDayOfWeekForString`).
+
+3. **Invalidate pattern cache** — `_weekdayPatterns` is built lazily from `weekdayVocab()`. Adding entries to the array changes the return value; since the cache is built per `MatchInput` instance, no reset needed.
+
+4. **Add regression tests** to `src/test/suite/match-input-vocab.test.ts`:
+   - `"task week Finalize Shoppinglist"` → Bug 1 regression
+   - `"mo"`, `"tu"`, `"we"`, `"th"`, `"fr"` each → correct weekday offset (same as 3-letter form)
+   - `"w15"` → week 15, no regression from `recognizeWeekNum` priority
+
+## Test scenarios
+
+| Scenario | Input | Expected |
+|----------|-------|----------|
+| Bug 1 regression — week+text | `"task week Finalize Shoppinglist"` | flag=task, text="Finalize Shoppinglist", hasWeek=true |
+| Bug 1 regression — week alone | `"week"` | hasWeek=true, no crash |
+| Bug 1 regression — w15 still numeric | `"w15"` | week=15 |
+| 2-letter alias mo | `"mo"` | same offset as `"mon"` |
+| 2-letter alias tu | `"tu"` | same offset as `"tue"` |
+| 2-letter alias we | `"we"` | same offset as `"wed"` |
+| 2-letter alias th | `"th"` | same offset as `"thu"` |
+| 2-letter alias fr | `"fr"` | same offset as `"fri"` |
+| No regression — task do | `"task do the shopping"` | flag=task, text="the shopping" (do = German Thursday) |
+
+## Dependencies
+
+- **Requires #177 tokenizer branch** — all changes land in `feat/177-smart-input-tokenizer`. This issue closes together with #177 in the same PR.
+
+## Risk
+
+| Risk | Mitigation |
+|------|-----------|
+| `we`/`th` false-positive on common words | Accepted per spec; tokenizer marks them `ambiguous`, yellow border visible to user |
+| `fr` duplication (English + German section) | `getDayOfWeekForString("fr", locale)` returns 5 (Friday) for all locales — result identical |
+| `_weekdayPatterns` cache stale | Cache is per-instance, built lazily on first `recognizeWeekday` call — no stale state possible |
+
+## Rollback
+
+Part of #177 PR. Revert the `weekdayVocab()` addition (two lines) if 2-letter aliases cause regressions after release.
+
+## Reference spec
+
+[docs/specs/2026-06-01-fix-230-smart-input-week-and-weekday-aliases.md](../specs/2026-06-01-fix-230-smart-input-week-and-weekday-aliases.md)