docs(worker): spike contract for trivial diffs — evidence or declared skip, never post-hoc narratives

[thewrz]

This was written agentically; verify its assertions:

Why

Orchestrators bounced two fleet workers for marking "SPIKE + REVERT: N/A" on code-bearing work and demanded corrected reports — but a report rewritten on demand after completion proves compliance, not process, and invites confabulated spike narratives. Medium-effort workers may also legitimately skip spikes on trivial diffs (a 5-line enum addition does not need a throwaway pass).

Acceptance criteria

• worker-prompts.md defines when a spike may be declared skipped (e.g. diff under a stated threshold touching only existing patterns) with a one-line justification in the handback.
• For performed spikes, the report cites transcript evidence (the spike edit + revert), not a narrative.
• Root validation stops requesting post-hoc report rewrites; it accepts declared-skip-with-justification or evidence-cited spikes, and bounces only absent/unjustified cases.

Evidence

2026-08-13 fleet night (downstream repo A #15/#17 report-correction cycles).

🤖 Co-authored by Claude Fable 5.