feat(knowledge): conflict resolution — agent annotates, nightly executor applies (agents' KB #4)

[mkreyman]

What — route-the-findings step 1: conflict resolution

#224/#225 detect and surface conflicts. This closes the loop: the retrieving agent (which has the live context the nightly job lacks) records a verdict; a trusted nightly executor applies it. Judgment stays with the grounded agent — the KB never re-judges. No LLM (dismiss/supersede only; merge is the later LLM step).

Design

• Separate conflict_resolutions table — article_links are immutable by design, so the verdict lives in a new mutable row. One row per canonical (sorted) pair; re-annotation upserts = last-write-wins, so the freshest grounded judgment governs.
• annotate_conflict/3 (agent, non-destructive → agent role): dismiss | supersede | merge, with authoritative_article_id (winner) for supersede/merge, plus classification / evidence / confidence. dismiss takes effect immediately (pair drops from the queue + the article surface); supersede/merge defer.
• execute_conflict_resolutions/2 (nightly, in KnowledgeLintWorker, system-privileged): applies only high-confidence supersedes — reuses create_link(:supersedes) to link winner→loser and transition the loser to :superseded (reversible + audited). Bounded. Lower confidence / merge left for review / the LLM step.
• Queue + get_article field now exclude resolved pairs — the conflict queue shows only OPEN conflicts.

This is the division we agreed on: agent judges (cheap, in-context, non-destructive), privileged batch executes (reversible-only, above a confidence bar), humans get the rest.

Surface

• POST /api/v1/knowledge/conflicts/resolve (agent+).
• MCP v2.27.0 knowledge_resolve_conflict. RLS on the new table.

Tests (+9 Elixir, +1 MCP)

dismiss-immediate + queue-drop; high-conf supersede applied (loser :superseded + :supersedes link created); sub-high not applied; last-write-wins across pair order; get_article drops resolved; supersede requires authoritative; controller dismiss/supersede/422; MCP plumbing.

Full gate green: format, credo --strict, dialyzer, 3057 tests, 0 failures; 53 MCP tests. Migration runs on deploy via release_command.

What's still open (honest)

• merge disposition is recorded but not executed — that's US-20.1: Documentation page with setup guides #4 step 2 (the isolated LLM-synthesis increment, drafts-only, behind the confidence gate).
• The tool-description pointers + a wiki playbook article (the "when you see a conflict, here's the protocol" instruction) are a small follow-up.