enhancement: recovered judge verdicts are indistinguishable from clean ones in report.json #321

Problem / motivation

When the judge agent errors but leaves a salvageable FinalMessage, agentCallError intentionally recovers it (CHANGELOG-documented and unit-tested behavior — this request does not question that design; the recovered output passes the same strict validation as a clean one).

The gap is observability: in report.json, a recovered verdict is indistinguishable from a clean one. The recovery is WARN-logged to the console, but nothing machine-readable records it — so a CI gate consuming reports cannot tell "judge was healthy" from "judge crashed/timed out and its output was salvaged". Across a benchmark run, a degrading judge engine is invisible exactly where judgments are aggregated.

Notably, the precedent already exists in the same schema: gate-short-circuited criteria carry "skipped": true, and judge.Result has skip_reason/error_reason slots — skill-up already treats abnormal verdicts as explainable; the recovery path just isn't wired into it.

Proposed solution

Surface the recovery in report.json (not grading.json, which is an Anthropic-compatible contract). The plumbing mostly exists: SessionResult.Warnings is already a field and buildResult already holds the session — carrying the recovery warning along that channel would make the change small. Any machine-readable marker (e.g. a recovered: true / warning entry on the judge result) solves it.

Alternatives considered

• Do nothing (console WARN is enough for humans) — leaves automated consumers blind; infrastructure noise then hides inside aggregate scores.
• Put it in grading.json — rejected: that file is an Anthropic-compatible contract.

Additional context

Found via deterministic fault injection of the judge channel (custom engine emitting exit_code=124 with a valid final_message): recovered verdicts produce reports structurally identical to healthy controls except timing fields. Related: #319 / #320 (found in the same fault-injection pass). The gate-skip path already demonstrates the desired disclosure shape ("skipped": true on judge criteria when the expect gate fails).