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51dd42f9db docs(databasev2): rewrite iteration 2 to match what was designed and built
Flagged by the developer: the iteration still described the pre-brainstorm
three-mode design behind a "superseded in part" banner while four tasks had
landed against it.

- iteration 2 rewritten around the shape as built: two keys
  (`durable: true|false`, `resident: all|keys`), not a `mode:` enum with
  `cold`. status refine -> in-progress
- added a task-by-task progress table with commit hashes, and split the
  acceptance criteria into MET (each with how it was verified, not just that
  it passed — e.g. the goldens-unchanged claim is `git diff` over golden/
  being empty after a WOC_BLESS run, since blessing rewrites all of them) and
  OUTSTANDING with the task that owns each
- kept the history rather than deleting it: the three-mode replacement, the
  "one real rewrite" that was fiction, and the opposite half that turned out
  genuinely deep. An iteration file is where that record belongs
- board row rewritten to agree; the track index's "the lever" section, its
  principle-7 paragraph and its sequence rationale all still taught the dead
  three-mode design

ITERATION 6 IS NOW LARGELY SUPERSEDED, and bannered as such rather than
quietly gutted. `resident: keys` is the ceiling-raiser and it lives in
iteration 2 (tasks 5c/5d). More than relocated: 6's premise — a user-space
resident working set with faulting and 5's eviction policy — was specifically
REJECTED by the spec in favour of the kernel page cache, since a pread against
a cached page is a memcpy. What may still be left is recorded honestly: revisit
only with a measurement showing the page cache insufficient. Its fork list
survives, especially "does the language surface the fault cost at the use
site", which is still open and still the largest question about what writeonce
is. The sequence rationale is amended too — it had 6 as the ceiling-raiser and
5 as a prerequisite on the critical path; neither holds.

Docs only. linkcheck 0 broken / 0 anchors.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-27 13:10:30 +02:00
746dc2b42b docs(databasev2): third track — the database beyond RAM, with per-table storage modes
- docs/stories/databasev2/, numbered from 1. Six PENDING database iterations
  moved from the language track and renumbered, keeping the old id in
  `was_language_iteration:` so a search for "iteration 32" still finds it:
  32 -> 3 WAL checkpoint, 23 -> 4 io_uring commit, 33 -> 7 single-file store,
  27 -> 8 query grammar, 20 -> 9 cross-program, 21 -> 10 keypair auth.
  Done work (9, 9b, 22) stays as v1 history; language 18 left whole
- the problem, read off the engine not guessed: rows are malloc'd slabs with
  addresses stable forever, NO eviction/spill/paging anywhere in database/src,
  the WAL never checkpoints so boot replays all history, and durability is one
  process-global WO_DATA so no table can say it matters more than another.
  An allocation failure IS a clean catchable WO_T_OOM — but swap thrash
  arrives first and carries no error signal at all, which is the real hazard
- four new iterations:
  1 measure the ceiling FIRST (curve not cliff; the three exits; kill -9 at
    exhaustion) — every later default should follow from a number
  2 `@table(mode: ram | durable | cold)` — the grammar ask. Small surface
    (Ast.table_cfg gains a key, the parser already rejects unknown args), big
    semantics: `durable` defaults so nothing changes silently, and the
    compiler refuses a durable row holding a `ref` into a ram table
  5 bounded tables + refuse/evict/back-pressure, shedding BEFORE the OS acts
  6 cold tiering — mostly forks, incl. whether the language surfaces the
    fault cost and whether @unique on cold is refused outright. A paged
    B-tree stays rejected: if tiering needs one, reject tiering
- 39 links repointed, link TEXT renumbered to track-local ids; arc gains one
  pointer row replacing the six moved; board + board-views cover three tracks
- linkcheck 0 broken / 0 anchors; no code blocks in any story

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-26 20:52:48 +02:00