feat: add non-blocking installation migration controller

[ericlitman]

Summary

• Persist the initiating task as ThreadBear's main task and keep that identity stable across reinstall.
• Add one resumable migration controller with the three explicit phases, single-controller enforcement, main/controller scope exclusion, and applied:true convergence gating.
• Keep installation non-blocking for the persistent task, refuse uninstall during active migration, and update the public/installed lifecycle guidance and status contract.
• Require status to reject modified installed skill or managed AGENTS guidance, with corruption regressions for both surfaces.

Tests

• go test ./...
• go test -race ./...
• go vet ./...
• Darwin arm64 and amd64 cross-builds
• cmp -s INSTALL.md site/install
• sh -n install.sh site/install.sh scripts/release-smoke.sh
• git diff --check
• Exact CI production Go line check: 1,000 lines
• Shipped executable logic check: 1,262 lines against the 1,500 absolute ceiling

The installed candidate passed the pre-review Codex Desktop gate for fresh-task running and terminal rewrites, stable-subject preservation, explicit-target isolation/repaint, and bounded Stop behavior. The full 20-turn, 200-task, uninstall/reinstall, and published-artifact lifecycle remains the BEAR-104 closeout gate.

Linear: BEAR-104

[mobilyze-open-swe-studio2]

Open SWE Review found 1 potential issue.

Open in Web

[mergify]

Merge Queue Status

• ✅ Entered queue — 2026-08-01 02:44 UTC · Rule: default · triggered by merge protections
• ✅ Checks skipped · PR is already up-to-date
• ✅ Merged — 2026-08-01 02:44 UTC · at 4ec6a325dc87a70b773396f684346d6096587a8f

This pull request spent 17 seconds in the queue, including 4 seconds running CI.

Required conditions to merge

• github-review-approved [🛡 GitHub repository ruleset rule Mergify automatic merge queue]
  • feat: add non-blocking installation migration controller #101
• all of [🛡 Merge Protections rule Queue ready pull requests]:
  • -draft
    • feat: add non-blocking installation migration controller #101
• any of [🛡 GitHub branch protection]:
  • check-success = verify
  • check-neutral = verify
  • check-skipped = verify
• any of [🛡 GitHub branch protection]:
  • check-success = Open SWE Review
  • check-neutral = Open SWE Review
  • check-skipped = Open SWE Review
• any of [🛡 GitHub repository ruleset rule Mergify automatic merge queue]:
  • check-success = @mergify/Mergify Merge Protections
  • check-neutral = @mergify/Mergify Merge Protections
  • check-skipped = @mergify/Mergify Merge Protections