pv extract emits a PARTIAL graph on an unparseable binding.yaml (one dropped quote → 356 triples silently gone, --check agrees with itself) — it must refuse, naming the line #3640

What

contracts/binding.yaml on PR #3350's branch lost one closing " (commit d3cc76f1f, the QE2E-INV-001 note) and stopped being valid YAML at line 764. pv extract did not refuse. It emitted a graph with every bound symbol after the broken entry silently gone — prune::run, distill::run, harness_ir::*, ptx_explain::run — 356 triples smaller than main, and --check (committed == fresh) would have agreed with itself. Found by aprender-d4 on 2026-09-20 ~22:50Z only because the rebase regenerated contracts.nt under a pinned in-tree pv and the count was compared to main by hand. Fixed in da1ee1506 (one character; 156 entries parse again; extraction byte-identical to main).

This is tonight's absence-scored-as-conformance class with a fresh mechanism: a malformed input producing a confidently smaller output, confirmed by the instrument that caused it. Sibling of #3639 (producer failure invisible to the consumer) and of the stale-pv 107-triples-short case on #3600.

done_when

• pv extract (and every pv reader of binding.yaml) exits non-zero on a binding.yaml that does not parse, naming the file and line, and writes NO graph — mutation: drop one " at an arbitrary entry → RED with the line number; restore → GREEN, byte-identical graph
• the partial-parse path cannot be reached: a parse error is not an empty-tail; the case table covers unterminated string, bad indent, duplicate key
• pv extract contracts --check on the mutated tree is RED for the parse reason, not for a count delta

Refs #3350 (the branch that carried it), #3639, #3641 (the consumer-side floor).