Legacy NULL-scope dedupe only compared Gitea targets, so duplicate rows
with the same provider key and issue but different fingerprint/status/
event_count/etc. collapsed to the lowest link_id and silently dropped
observation data. Migration now compares all meaningful observation
fields and refuses to discard conflicts (#619 RC3 / #613).
Address remaining PR #619 blockers on head 783ea88:
- Deduplicate legacy NULL-scope incident_links before normalizing to ''
- Fail closed when duplicate rows disagree on Gitea target
- Require non-empty expected_head_sha for PR assign and mutation
Address REQUEST_CHANGES on PR #619:
- require_valid_assignment rejects terminal work states and head drift
- incident_links scope keys normalize NULL/blank to '' for UNIQUE
- remove trailing whitespace in control-plane-db-substrate.md
Add SQLite single-writer MVP control plane per the allocator ADR:
sessions, work_items (issue/pr only), atomic assign+lease, mutation
gates, terminal-lock index, and provider-neutral incident_links.
DB coordinates concurrency; Gitea remains assignable work; raw
Sentry/GlitchTip incidents are never work items. #600 and #612 build on
this substrate.
sysadmin