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2 Commits
Author SHA1 Message Date
timothy 1641ca8305 fix(578): the LIKE prefilter under-matched every accented artist; make the superset provable
Review of 1b78dc9e found the pre-filter's correctness claim was false, and the claim was in the
decision record as well as the code.

F1 (high). The pattern JSON-encoded the whole query prefix on the reasoning that the stored text
escapes non-ASCII, so encoding the prefix the same way would line up. It does not: SQL LOWER()
lowercases the *escape text* (`É` -> `é`); it cannot case-fold the codepoint that escape
denotes. So `q=é` built `%"é%`, the stored `Édith Piaf` never matched, and the row was
discarded before the in-memory filter could accept it. Every accented artist — Beyoncé, Björk,
Sigur Rós, Édith Piaf — was silently unsuggestable, which in a music library is the common case.

The invariant that was missing, now stated in the code: the SQL pre-filter is an OPTIMIZATION. It
may over-match; it must never under-match. Correctness lives in the in-memory filter. So the pattern
now narrows only on the leading run of characters the JSON writer stores verbatim and stops at the
first character it cannot prove — `q=Beyoncé` still narrows on `beyonc`, `q=é` narrows on nothing
and leans on the row cap. Soundness rests on two facts now asserted by exhaustive computation rather
than argued: no non-ASCII codepoint in U+0080..U+10FFFF OrdinalIgnoreCase-equals a printable ASCII
character (false for InvariantCultureIgnoreCase, which folds ~190 — the choice of Ordinal is
load-bearing), and the exact set of ASCII the encoder escapes.

F1b. `UseRequestLocalization` honours Accept-Language, so the culture was caller-controlled and
`ToLower()` plus the default linguistic `StartsWith(string)` let a header change the answer.
Comparison is now OrdinalIgnoreCase and ordering StringComparer.Ordinal throughout — including the
shared FilterSortTake that state/video_dynamic_range/content_rating also use. Sets unchanged,
order now ordinal rather than culture-dependent.

F2. The merge comment asserted an exactness the code does not have: sources truncate by their own
ordering (DB collation / primary key), not the merge's, so a dropped value can outrank a survivor.
Comment and record now say best-effort, exact only below the truncation points.

F3/F4. The cap now rides `ORDER BY Id` rather than the JSON column: MySQL sorts TEXT by only
max_sort_length bytes, so the old ordering was not deterministic there, and sorting the whole
matching set was avoidable work. What the cap still does NOT bound is the scan — a leading-wildcard
LIKE cannot seek an index — so that cost is now documented as accepted, with a normalized
`SongArtist` table named as the follow-up candidate rather than left implicit.

Every clause above is covered by a test verified to FAIL when that clause is mutated (old pattern
builder: 5 red; culture chain: 3 red; cap=3 / cap=limit / ORDER BY json / no cap: red each).

F5. Converted to a proper supersession. The old record did not merely hold a stale fact — it
recorded song/music-video credits as an "intentionally-uncovered gap" and album_artist as
unsupported, and this reverses that call, which `docs.decision-lifecycle` says is never a
line-edit. `api.search-field-values` is archived with its original prose restored, and
`api.search-field-values-sources` replaces it carrying the whole endpoint contract.
2026-07-27 03:10:35 +02:00
timothy fba5233caf feat(610): split the decision corpus into one YAML-frontmatter file per record
PR Gates / CI image pin matches docker/ci (pull_request) Successful in 11s
PR Gates / Docs update reminder (pull_request) Successful in 16s
PR Gates / decisions lifecycle (pull_request) Failing after 23s
Build ErsatzTV Image / Formatting (changed .cs conform to .editorconfig) (pull_request) Successful in 1m17s
Build ErsatzTV Image / API docs in sync (OpenAPI + endpoint index) (pull_request) Successful in 1m29s
Build ErsatzTV Image / Build & test (.NET) (pull_request) Successful in 8m5s
Build ErsatzTV Image / EF migration integrity (SQLite + MySql) (pull_request) Successful in 16m5s
Build ErsatzTV Image / Functional E2E (curl + UI contracts) (pull_request) Successful in 17m6s
Build ErsatzTV Image / Build & push image (amd64) (pull_request) Has been skipped
168 records -> docs/decisions/records/<area>/<topic>.md (163 active, 23 dirs) and
docs/decisions/archive/<area>/<topic>.md (5 archived). The filename IS the key,
so one-active-record-per-key becomes a filesystem property rather than a
validator check, and supersession becomes a `git mv`.

WHY: the monolith was a concurrency problem before an aesthetic one. A
3,900-line append target made parallel sessions collide -- PR #605 and PR #614
both hit append-vs-append conflicts during routine rebases, and hand-resolving
those inside the corpus is exactly the operation the rationale-rewrite guard
exists to police.

HOW IT IS VERIFIED: a ~170-file diff cannot be meaningfully read, so correctness
does not rest on reading it. The parser was taught BOTH formats first, so the
body-diff guard parses the old form at the merge-base and the new form at head --
the migration validates itself, no bypass. The proof is a field-level equivalence
harness: 168 records before and after, zero lost, zero gained, zero field
mismatches, zero rationale bodies differing. Reviewers should scrutinise the
harness; it is the actual evidence.

What measuring caught that reading would not have:

- ~500 lines sit OUTSIDE any record -- decisions.md's lifecycle schema and each
  topic file's preamble, mostly the only copy. Source files are kept and
  stripped, never deleted. They also cannot be filed per-area: topic files hold
  several areas and 4 of 23 areas span several files.
- Archive discovery was a non-recursive glob; after the split it found ZERO
  archived records, surfacing as four bogus "supersedes points to unknown key"
  errors rather than an obvious failure.
- ~32 live docs point into the corpus BY DATE, which the split dangles. Each
  stripped file now ends with a generated "Records formerly in this file" index,
  which also rescues the identical breadcrumbs in old issue comments.
- decisions.md's "In this file:" list was 97 same-file anchor bullets that the
  split makes WRONG, not merely stale. Dropped; the generated index replaces
  them with links that resolve.

The equivalence harness now runs against a checked-in FIXTURE, not the live
corpus. The earlier version migrated the real tree, which made it a one-shot:
the moment the migration landed there was nothing left to move and the tests
failed for reasons unrelated to the code. A fixture keeps them testing the
SCRIPT rather than the repo's current state.

Keys preserved verbatim, warts included: `sched` (12) and `scheduling` (1) remain
two directories for one concept. Renaming a key is not a move -- it changes
identity, breaks the equivalence proof, and invalidates MemPalace's per-key
drawers. Taxonomy normalisation is separate work.

refs #610
2026-07-25 19:45:09 +02:00