📝 Allow the floating-promise header in test files

Agents may add the fixed file-level typescript/no-floating-promises
oxlint-disable header at the top of a `*.test.ts` file — the
expectTypeOf() misidentification is a documented false positive
(development/testing.md § Known issues) and the await/void workarounds
collide with eslint/no-void. Every other suppression stays the human
last resort it was.

AGENTS.md

@@ -25,10 +25,10 @@ first-action facts. Do not restate evolving prose here — it will drift.
 Don't silence the type system to force a green run. As an agent these are forbidden:
 
 - `// @ts-nocheck`, `// @ts-ignore`, `// @ts-expect-error`
-- `// oxlint-disable` / `// oxlint-disable-next-line`
+- `// oxlint-disable` / `// oxlint-disable-next-line` — the sole exception is the fixed file-level `typescript/no-floating-promises` header at the top of a `*.test.ts` file, spelled exactly as [CONTRIBUTING.md § Rules the tools don't enforce](./CONTRIBUTING.md#rules-the-tools-dont-enforce) prescribes
 - `as` casts used to push an expression through (type-aware oxlint already flags unsafe assertions)
 
-Fix the root cause with the type system instead — narrowing, generics, `satisfies`, conditional / mapped types, utility types (`NonNullable`, `Exclude`, …). TypeScript can express it; that's the intended tool. The `oxlint-disable`-location rule in [CONTRIBUTING.md § Rules the tools don't enforce](./CONTRIBUTING.md#rules-the-tools-dont-enforce) is a **human** last-resort convention (so a reviewer can spot a deliberate suppression) — it is not permission for you to add one. If the types genuinely cannot express something, stop and surface the conflict (commit message / handover) rather than suppress it.
+Fix the root cause with the type system instead — narrowing, generics, `satisfies`, conditional / mapped types, utility types (`NonNullable`, `Exclude`, …). TypeScript can express it; that's the intended tool. The `oxlint-disable`-location rule in [CONTRIBUTING.md § Rules the tools don't enforce](./CONTRIBUTING.md#rules-the-tools-dont-enforce) is a **human** last-resort convention (so a reviewer can spot a deliberate suppression) — it is not permission for you to add one, except the one fixed `*.test.ts` file-level header named there. If the types genuinely cannot express something, stop and surface the conflict (commit message / handover) rather than suppress it.
 
 The same applies to the checks themselves: **never `git commit --no-verify`** (or otherwise skip a pre-commit / pre-push hook). The checks are fast and offline, so a redundant run is fine — bypassing a hook to get green is the identical anti-pattern. If a commit already skipped a hook, redo it through one: `git reset --soft HEAD~1 && git commit -C <skipped-sha>`.
 

CONTRIBUTING.md

@@ -151,7 +151,11 @@ reaches for by default:
 - **`oxlint-disable` directives live in source, not `.oxlintrc.json`.** The
   trade-off must sit next to the code it silences. This is a _human_ last-resort
   convention; agents must not add these — see
-  [AGENTS.md § Never do](./AGENTS.md#never-do). (why:
+  [AGENTS.md § Never do](./AGENTS.md#never-do). The sole agent exception is the
+  fixed file-level header at the top of a `*.test.ts` file, spelled exactly:
+  `/* oxlint-disable typescript/no-floating-promises -- expectTypeOf() is a sync
+type-assertion library that the type-aware linter misidentifies as a promise
+*/` — any other suppression stays human-last-resort. (why:
   [development/tooling.md](./development/tooling.md#oxlint-disable-directives-live-next-to-the-code))
 - **Don't put slow / network / whole-project scans in `check` or pre-commit.**
   Advisory scans are not correctness gates; they belong under `maintain:`. (why: