bug(unic-archon-dlc): `reconcile` marks a finding fixed when the next review omits it, and `post` resolves the thread

Observed

Run 3, unic-dlc-pr-review iteration 2 on PR 5881, byte-identical commit 08e2523 to iteration 1. The second review did not mention six of the first iteration's thirteen findings (confidence 78, 74, 72, 72, 64, 61, all Standards). reconcile returned:

{"iteration":2,"fixed":6,"still_present":7,"regressed":0,"new":4,"prior_count":13,"verdicts":13,"unverified_fixed":0,"unmatched_priors":0}

post then set threads 65901, 65904, 65905, 65906, 65909 and 65910 to Azure DevOps status fixed. Nobody changed the code and nobody resolved anything by hand.

Why it matters

A duplicate thread is noise a reader discards. A false fixed is a defect a reader stops looking for. On a repository with no CI the pull request is the only record, so this turns the reviewer's variance (#{G5}) into false state on the client's PR. unverified_fixed exists and stayed 0, so the Box does not even flag the inference.

Evidence

• Findings register, § "G. What run 3 taught about the instrument", row G4: https://github.com/unic/unic-agents-plugins/blob/bcf688a/docs/research/2026-08-31-dlc-run-2-findings.md
• Run record and harvested artefacts: ~/Desktop/run3-parked/ on the maintainer's machine (artefacts-908e3735…-pr-review-2038/findings.json, threads.json; az devops invoke … pullRequestThreads for PR 5881)
• Dispatch record: #457 from comment 5698289748 down

Not decided

• Whether fixed requires evidence from the diff (the prior finding's file and line changed since the prior iteration) or from a re-check of the prior finding against the current tree.
• What post does with a fixed it cannot verify: reply without resolving, or resolve with an unverified marker.
• Whether unverified_fixed should be the default verdict for an omitted prior.

Filed 2026-09-17 by wayfinder-orchestrator-10 from run 3's measurements. needs-specs: grill before dispatch.

Start by reading the findings register at docs/research/2026-08-31-dlc-run-2-findings.md and the dispatch record in issue #457, then locate the reconcile and post entry points. Compare the harvested findings.json and threads.json for PR 5881 with the reported output. Done requires an agreed specification for omitted findings and behavior for unverifiable fixed results, plus behavior that matches it.