docs(agents): Prime Directive #12 — contract-first (fix the metadata, not the runtime) (#2424)

Codify the rule that governed the AI-flow create_record fix: when metadata
doesn't work, first ask if it's spec-compliant and whether the fix is the
long-term-correct direction. Fix the producer + reject off-spec input at
authoring/publish; never add a lenient `??` alias in a consumer (executor /
renderer) to tolerate non-compliant metadata. `packages/spec` stays the single
strict contract; change the spec only when it is genuinely wrong. The existing
`cfg.filter ?? cfg.filters` style fallbacks are debt, not a pattern to extend.

Same principle added to the cloud and objectui AGENTS.md.

Co-authored-by: Jack Zhuang <277994282+os-zhuang@users.noreply.github.com>
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

Author: os-zhuang

AGENTS.md

@@ -66,6 +66,7 @@ Other scripts: `objectui:bump` (pull only), `objectui:build`, `objectui:clean`.
 9. **`OS_` env-var prefix.** All ObjectStack-owned env vars MUST start with `OS_`. When renaming a legacy var, use `readEnvWithDeprecation('OS_NEW', 'LEGACY')` from `@objectstack/types` (keeps legacy working one release). Third-party exceptions kept as-is: `NODE_ENV`, `HOME`, `OPENAI_API_KEY`, `TURSO_*`, OAuth `*_CLIENT_ID/SECRET`, `RESEND_API_KEY`, `POSTMARK_TOKEN`, `AI_GATEWAY_*`, `SMTP_*`. See #1382.
 10. **File issues for out-of-scope findings — don't silently expand scope or leave them buried.** When you hit a bug, gap, or unenforced capability that's unrelated to the current task, or too large to fix in scope, open a GitHub issue (`gh issue create`) with a clear repro/decision and link it from your PR. Corollary: **never advertise or demo a capability the runtime doesn't actually deliver** (declared ≠ enforced) — fix it, trim it, or file an issue, but don't fake coverage. Example: the spec declares 9 validation-rule types but the write-path validator enforces only 3 (`state_machine`/`script`/`cross_field`); the other 6 are tracked in #1475 rather than demoed in the showcase.
 11. **Worktree-first — never edit on the shared `main` checkout.** This repo is edited by **multiple agents at once**; the shared `main` tree has its HEAD switched and reset *under you*, silently clobbering uncommitted work. Before your **first file edit**, you MUST be in a dedicated worktree on a feature branch: `git worktree add ../framework-<task> -b <branch> main && cd ../framework-<task> && pnpm install`. A PreToolUse hook (`.claude/hooks/guard-main-checkout.sh`) **enforces** this — it blocks `Edit`/`Write`/`NotebookEdit` whenever HEAD is on `main` (override for a deliberate non-task fix with `OS_ALLOW_MAIN_EDITS=1`). Full playbook below.
+12. **Contract-first — fix the metadata, not the runtime.** This is a metadata-driven framework: `packages/spec` is the one contract between metadata *producers* and the runtime/renderers that *consume* it. When a piece of metadata "doesn't work," ask **first**: *is it spec-compliant? is this the long-term-correct direction?* If the metadata is wrong, fix it at the **producer** and **reject it at authoring/publish** (validation / lint) so the error surfaces loudly — do **not** add a lenient alias or `??` fallback in the consumer (a node executor, the REST layer, a renderer) to tolerate off-spec input. A tolerant fallback fossilizes the wrong convention into a second de-facto contract, dilutes the spec, and hides the producer's bug — one strict contract beats N dialects. This is an **internal** contract (we own both ends), so "be liberal in what you accept" (Postel) does **not** apply — that's for untrusted boundaries. Change the **spec** only when the spec itself is genuinely wrong, and then deliberately (edit the Zod schema + migrate), never by accreting consumer-side fallbacks. The existing `cfg.filter ?? cfg.filters` / `cfg.objectName ?? cfg.object` in the flow executors are **debt to pay down, not a pattern to copy**. *Worked example:* an AI-authored `create_record` used `fieldValues` / `today()` / `{{trigger.record.id}}` while the executor reads `fields` / `{TODAY()}` / `{record.id}` → the fix was correcting the authoring skill + a publish-gate lint that rejects the wrong shape (cloud#688), **not** a `cfg.fields ?? cfg.fieldValues` runtime alias (framework#2419, rejected). Strengthens #5.
 
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