fix(X402-43): variant-aware extensions.bazaar validation (D.5)

[fardinvahdat]

Summary

X402-43 (D.5) — bug fix carrying the v0.3.2 metadata-propagation work forward. Variant-aware extensions.bazaar validation per ADR-004 Pillar 1's verdict semantics + the original bug report from @AsaiShota on #72.

Closes false-positive implementation_issue on every body-discovery v2 service.

Why

@x402/[email protected] ships TWO discovery-extension variants:

Variant	Top-level fields	Used by
MCP-discovery	name, description	MCP-style services (TheRoosters, GM, hypeprinter007 #65)
Body-discovery	info.input + info.output + schema	API-style services with declareDiscoveryExtension(...) (AsaiShota test-echo-cdp, 0xdespot hyperD)

v0.3.0/0.3.1 assumed only the MCP shape. PR #70's D.1 manifest hygiene check carried the same assumption into well-known.ts. Real-world v2 services using the Body-discovery shape verdict to implementation_issue despite being correctly implemented — verdict overrides the substantive indexing-probe signal.

What changes

New file: src/bazaar/extensions-bazaar.ts (variant detection + validation helper)

• detectBazaarVariant(bazaar) — body-discovery indicators win when all 3 present (info.input + info.output + schema); else assume mcp-discovery per ADR-004 "else assume Mcp"; third "unknown" branch is defensive for future @x402/extensions variants
• validateBazaarExtension(bazaar) — variant-appropriate required-field check; pure-function, presentation-free; callers format messages in their own voice

src/bazaar/challenge.ts (refactor)

Inline validation replaced with validateBazaarExtension call. mcp-discovery behavior preserved (regression-clean). New body-discovery pass + fail paths. New defensive "unknown variant" pass path.

src/bazaar/well-known.ts (refactor)

Same refactor as challenge.ts. The pillar-2 D.1 manifest hygiene check (PR #70) now respects variant.

JSON output additive

detail.variant field added to extensions.bazaar-related check results. Additive per the JSON API stability commitment (ADR-004 Pillar 2); no field renames/removals.

CHANGELOG.md [Unreleased] ### Fixed

Crediting @AsaiShota for the diagnosis + @0xdespot for the second-voice corroboration. ### JSON API subsection documents the additive detail.variant field.

Acceptance criteria (X402-43)

• Re-running bazaar-check against AsaiShota's x402-market-api.lien-studio-akiyama.workers.dev/api/seller-4068b8fc/test-echo-cdp under v0.3.2 produces challenge: pass for the body-discovery variant — verified via the body-discovery happy-path test in bazaar-challenge.test.ts
• hyperD-style body-discovery shape similarly produces clean envelope verdict — same code path
• Verdict envelope no longer overrides the substantive signal on body-discovery services — body-discovery is its own success path
• Test coverage: ≥4 cases per affected file (8+ tests total) — challenge.ts: 4 new; well-known.ts: 4 new; plus 13 helper unit tests = 21 new tests
• Default-deny path: unknown variant skips shape validation, emits info-level message — challenge.ts returns pass with "variant not recognised; skipping" message; well-known.ts handles via catch-all branch
• CHANGELOG entry crediting @AsaiShota + @0xdespot

Strict audit gate — abbreviated (user-in-loop mode per ADR-003)

• Stage 1 pre-work: branched off bd7494a (PR feat(X402-41): ADR-004 — v0.3.2 scope + JSON API stability + facilitator-aware verdict semantics #75 ADR-004 just-merged); .gitignore WIP on branch but NOT staged (hard rule docs(X402-8): SPEC.md v0.1 — implements the wedge from ADR-001 #7 preserved); 4 source files modified + 2 created + 1 CHANGELOG appended (one-thing-per-PR: variant-aware refactor)
• Stage 2 implementation: helper extracted + 2 checkers refactored + 21 new tests + CHANGELOG ### Fixed entry crediting evidence sources
• Stage 3 correctness: ✅ typecheck clean; ✅ lint+prettier clean; ✅ 450 tests pass + 4 skipped (was 429+4; +21 new); ✅ build clean; ✅ check:publish-surface 98 files / 363 KB / 0 devDep imports (under 400 KB cap, +10 KB for the new helper + tests)
• Stage 4 edge cases: ≥10 edges enumerated — empty {} (mcp default, fails as before — regression preserved); null/undefined (caller pre-screens); hybrid both-shapes (body wins per detection order); info non-object (falls to mcp); info.input/output null after detection (body-discovery, validate-fails); unicode in fields; future 3rd variant (defensive unknown path); concurrency (pure-function, no shared state); whitespace-only strings (.trim() preserved); foreign-key objects (mcp default per AC)
• Stage 5 gap check: all 6 X402-43 AC items satisfied; CHANGELOG entry added (was missing in first pass; flagged + remedied in stage 5); cross-references to ADR-004 + X402-46 (D.3 not_applicable_non_cdp state) + X402-47 (fixture consumption) all present
• Stage 6 ship: this PR; awaiting maintainer merge per [[user-merges-prs-themselves]]

What unblocks on merge

• X402-42 (D.4) is parallel-safe and can continue independently
• X402-44 (JSON API stability) can now snapshot the new detail.variant field as part of the baseline
• X402-47 (fixture consumption) acceptance against anchor-x402's JPYC Polygon rail will use the new variant-aware path

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Project	Deployment	Actions	Updated (UTC)
x402trace-dogfood	Ready	Preview, Comment	May 22, 2026 9:32pm