[dezren39]

Closes #1685. Design #1684 phase 1 — tests/tables only, no production changes under packages/ai/src/.

What

One shared fidelity corpus, packages/ai/test/tool-schema-fidelity-corpus.test.ts, holding a checked-in disposition table per translator — antigravity convertSchema, GeminiJsonSchema.normalize, ToolSchemaProjection.moonshot — and running every row through its translator, asserting the projected shape the table states. The tables are the named oracle (header comment; model-based testing per design #1684's contract: preserved / approximated-named-with-direction / refused / known-lossy-with-issue-link, never silent).

Coverage: every keyword shape exercised by #1548/#1550/#1556/#1573/#1585/#1667 — boolean subschemas, multi-valued type, allOf/not-only roots, ARRAY without items, mutually recursive $defs, draft-04 bounds, draft-07 tuples — plus the built-in-schema keyword set probed row by row against the current translators.

Known-lossy rows (asserted as current behaviour, flip when their issues land)

• antigravity const dropped by the SCHEMA_FIELDS allowlist -> fix(ai): antigravity convertSchema drops const — a fixed-value parameter is sent upstream unconstrained #1557
• Moonshot prefixItems with items present folds into one items:anyOf -> fix(ai): moonshot tool-schema projection drops prefixItems when items is also present — position constraints are silently replaced #1574

Recorded named approximations include: Gemini loop-cut to {} (#1585), antigravity anyOf->oneOf for Anthropic targets (#1550, narrowing), Moonshot prefixItems fold when items is absent (widening). objectRoot forcing is recorded in the header note: it lives in the unexported tools() layer above moonshot(), which the corpus asserts directly.

Tests

On the laptop worktree (fleet CI-first policy; CI on this PR is the gate):

• bun test test/tool-schema-fidelity-corpus.test.ts test/tool-schema-projection.test.ts test/gemini-json-schema.test.ts test/provider/antigravity.test.ts — 139 pass, 0 fail on current main (32f3d6c)
• Corpus alone: 99 pass. Formatted with the repo's prettier config.
• git diff packages/ai/src/ is empty.

🤖 Agent note · queue task 9799 (repo-worker-opencode), phase 1 of #1684.