writeonce/docs/stories/language-runtime-database/done/09-database-engine.md
shoney.arickathil 57b4b56eae docs: stories foldered by state — done/ and refine/
- done/ (11): 1, 2, 3, 4, 6, 7, 7b, 9, 9b, 15, 16 — landed iterations
  (9/9b remainders live in the post-12 drain list, not in the files)
- refine/ (8): 9c, 9d, 9e, 9f, 9g, 11, 13, 14 — everything marked
  "no spec yet / brainstorm before planning"
- root keeps: 00-story (index), 05 (partial, plan 8 open), 8/10/12
  (specs or plans exist), 17 (parked, spec+plan approved), 18 (next)
- every cross-reference re-pathed and VERIFIED resolving: board, specs,
  plans, employee-list README, story table, intra-story links (moved
  files' relative links deepened one level; done/7b's 9e pointer now
  crosses to refine/)
- pre-existing dead link noted, not touched: refine/11-fibers.md points
  at docs/plan/exploration/fibers/00-fibers.md which does not exist
  (predates the move)

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-20 04:33:24 +02:00

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2.9 KiB
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# Iteration 9 — database engine
> Format: fiberloom `product/story-iteration-template`. Part of
> [Story — one language, one runtime, one database, one binary](../00-story.md).
## Goals
- The language's oldest promise executes on the new runtime: every class is
a table. `insert` and `select` stop trapping (`DB_STUB` retires) and run
against class-shaped row storage inside the VM's shards.
- Data survives anything: a typed write-ahead log with ack-after-fsync,
parallel boot replay, and a crash battery proving no committed row is
ever lost and no half-applied transaction ever visible.
## Acceptance Criteria
- What to achieve?
- **Given** a class annotated `@table` and a method inserting rows,
- **when** the method runs,
- **then** the insert is WAL-logged before acknowledgment, visible to
subsequent `select`, and the pricing fixture that previously trapped
`DB_STUB` now passes with real data.
- What to achieve?
- **Given** kill -9 at arbitrary points during committed writes,
- **when** the process reboots and replays,
- **then** every acknowledged commit is present, no unacknowledged
partial write is visible, and replay across shards completes without
manual steps.
- What to achieve?
- **Given** a `@unique` field and a duplicate insert,
- **when** it executes,
- **then** the insert traps with the unique-violation code and
secondary indexes remain consistent (maintained only through the
engine's row choke points).
## Out Of Scope
- Cypher/document query paradigms and `LIVE` subscriptions (the query
layer's later phases; `prototypes/wo-db` stays the reference).
- Cross-shard 2PC transactions; Postgres mirroring (exists on the Rust
side; ports after parity).
## Info
- Doctrine: RAM is authoritative; the WAL makes it durable; indexes drift
unless writes go through the row API — the Rust runtime learned this
lesson, the C engine enforces it.
- The wo-db overlap manifest keeps the C++ prototype and this engine
answer-compatible where features overlap.
- **Ownership/GC analysis (2026-08-15):** the engine and the VM heap are two
memory worlds crossed only by copy — rows store no VM pointers, GC-managed
values in stored fields are a compile error, and everything a query returns
is copied out — so the collector never traces rows and the engine never
counts references. The full analysis (row views as borrows without a
runtime net, cursor stability, GC-pause interaction) lives in the 9b
design's section 6:
[`2026-08-15-table-relations-query-design.md`](../../../superpowers/specs/2026-08-15-table-relations-query-design.md).
## Proposed Solution
- Execute the existing plan: `docs/superpowers/plans/2026-08-01-db-engine-binding.md`
(class-shaped row slabs with a choke-point row API, typed WAL + parallel
replay + crash battery, insert execution, doctrine-enforced indexes +
`@unique` trap, select subset, db corpus).