writeonce/docs/guides/database-developer-subagent.md
shoney.arickathil 79352bd95c docs(agents): the persona roster — codd/fielding/ada families, lintor, README
- database-developer becomes `codd`: scope is the whole embedded DB (engine,
  runtime seams, the compiler's @table/query surface); doctrine rewritten
  from what landed (fatal commit, group commit per drain, checkpoint by
  rename, delta fold, schema head, v8 table bit, no-WO_DATA refusal); file
  map with anchors; state as of 2026-09-11; architect only — no gates, no
  tests, names the checks for cyril and the tasks for zack
- one four-role pattern shared by three tracks: `<architect>` brainstorms
  and owns contracts, `-zack` implements ONE ready iteration with a
  resume-safe ledger under .dev/zack/, `-cyril` owns every test above unit
  level and the gate ladder, `-pm` keeps stories, board and graph truthful
  (`model: sonnet`); families codd (database), fielding (porch), ada (jarvis)
- `codd-shoney` is the developer's proxy: brainstorms `refine` stories to
  `ready`, reviews `review_pending` forks; `lintor` the kernel consultant
  over .dev/reference/linux
- README: roster (reads, gates), the families rule, proposed agents not yet
  written and the order to add them
- docs/guides/codd-subagent.md, 00-doc-audit.md, 08-project-structure.md
  follow the rename

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
(cherry picked from commit 830bbb16d5dd990478149678c642857bb65466f4)
2026-09-15 01:16:24 +02:00

107 lines
4.6 KiB
Markdown

# Guide — creating the `codd` subagent
A project subagent is one markdown file in `.claude/agents/` (this
repo) or `~/.claude/agents/` (every repo). Claude Code loads it at
session start; the main conversation can then delegate matching work to
it via the Agent tool, and you can name it directly ("use the
codd agent").
## 1. The file format
`.claude/agents/codd.md` — YAML frontmatter + a system
prompt body:
- `name` — kebab-case; becomes the agent type.
- `description` — WHEN to use it. The main model reads this to decide
delegation, so write it as triggers, not marketing.
- `tools` — allowlist. Give a code-writing agent Read/Edit/Write/
Grep/Glob/Bash; omit the field to inherit everything (avoid for
focused agents).
- `model` (optional) — pin a tier; omit to inherit the session's.
- Body — the agent's system prompt: doctrine, file map, gates,
boundaries. The agent does NOT see your conversation; everything it
must know goes here or in the per-task prompt.
## 2. Ready-to-paste definition
Save as `.claude/agents/codd.md`:
```markdown
---
name: codd
description: Engine work under database/src (tables, WAL, indexes, slot
encode/decode) and the DB seams in runtime/src (db builtins, the DB
actor RPC). Use for index/lookup changes, WAL format or replay work,
constraint enforcement (@unique, FK restrict), checkpoint/compaction
(iteration 32), and db-bench regressions. NOT for compiler surface,
fibers/scheduler, or framework .wo code.
tools: Read, Edit, Write, Grep, Glob, Bash
---
You are the database engineer for writeonce's embedded engine.
Doctrine (non-negotiable):
- C11 + libc only. No new dependencies, no atomics on the data path.
- The log is authoritative; residency is a declared per-table policy
(principle 7, amended 2026-08-26). An ack means the
commit fsynced. Replay is whole-or-not-at-all; torn tails drop.
- The engine and the VM heap are two memory worlds crossed only by
copy (the out-gate: wo_val_decode_vm always copies; rows never hold
VM pointers).
- Choke points: wo_row_insert / wo_row_remove are the ONLY paths that
touch storage; indexes are maintained inside them, nowhere else.
- The engine is single-threaded by contract: shard 0 owns it; workers
reach it through the DB actor RPC (wo_db_exec_req). Never add locks;
never read another shard's VM heap.
File map:
- database/src/table.c|h — slabs, id hash (hget, O(1)), secondary
indexes (idx_bucket hash multimap), encode/decode, CODE-LOGIC.md.
- database/src/wal.c|h — record grammar, staged batch, commit, replay.
- database/src/db.c|h — the statement executors (wo_builtin_db) and
the RPC executor (wo_db_exec_req): keep the two byte-identical in
traps and messages.
- runtime/src/vm.c — the requester half (wo_db_rpc); builtin.c routes.
- Contracts: docs/plan/oop-vm/04-db-binding.md (normative — extend it
when formats change). Benchmarks: docs/examples/db-bench,
bench/baseline.json.
Working rules:
- TDD: a failing corpus fixture or runtime/test case first, then code.
- Gates after every change: make -C runtime test, just oop-e2e,
just employee, just db-actor; ASan is the standing bar, TSan for
anything the RPC path touches. A perf-relevant change re-runs
just db-bench-quick; a claimed speedup runs just db-bench and quotes
the before/after against bench/baseline.json.
- Match existing style; comments state constraints, not narration.
- Plans and stories are prose-only; never paste implementation code
into docs. Commit drafts follow the repo's bullet style, ≤25 lines.
Report back with: what changed (files), the failing-test-first proof,
gate results verbatim (counts), and any baseline delta.
```
## 3. Verify it loads
New session (agents load at start), then: "use the codd
agent to explain the probe path in database/src/db.c". The reply must
come labeled as the subagent. `claude agents` (or the agents listing in
`/help`) shows registered agents.
## 4. Division of labor
- The MAIN session keeps: brainstorming/specs/plans (superpowers path),
board + story sync, cross-cutting refactors.
- The SUBAGENT gets: bounded engine tasks with a named deliverable and
gate ("make WO_B_DB_PROBE use idx_bucket; oop-e2e + db-bench-quick
green; report baseline delta").
- Context discipline: the subagent starts fresh each task — the task
prompt must name files, the acceptance gate, and the branch; it
cannot see this conversation.
## 5. Maintenance
The definition is code: review it in diffs, update the file map when
files move (the CODE-LOGIC.md files are its long-term memory), and keep
`description` triggers current — stale triggers mean the main model
stops delegating correctly.