[TheGreatAxios]

Summary

• Adds docs/TUI-064-compat-spike.md: the pre-0.6.0 compatibility spike for the staged @opentui/core 0.5.12 → 0.6.4 bump, with no version change and no code changes.
• Inventories every reflection/monkeypatch site in src/tui/ on the 0.6.4 breaking surface (13 sites with 0.6.0 dispositions), plus reproducible zero-scan greps proving zero uses of enableLayout, custom Renderable subclasses, render() overrides, yogaNode/getLayoutNode refs, and custom paint-hook/frame-cell reads in prod code.
• Flags the test-harness follow-ups: the 51 test suites (248 call sites) reading painted frames via captureCharFrame/captureSpans, the prototype-level reflection in markdown-rows.test.ts, and the e2e/ coupling through src/tui/test-helpers.ts.
• Records a qualified go/no-go (go, with the 0.5.17 intermediate uninspected and capture fidelity under NativePaintRecorder named as empirical gates) and corrections for later tickets in the series (no QR API in 0.6.4; detectLinks is a standalone export; Timeline uses state-change listeners, not events; markdown-parser.ts is not wholesale-deletable).

Verification

• bun run check passes (oxfmt + oxlint, tsc --noEmit, dead-export guard, build, bun test ./src ./e2e ./evals ./scripts — 8938 pass / 0 fail across 580 files).
• git diff --name-only origin/main...HEAD lists exactly one file; package.json and bun.lock are untouched.
• Every file:line citation in the doc spot-checked against the worktree; 0.6.4 API claims checked against the extracted @opentui/core@0.6.4 tarball (npm pack, no manifest change); zero-scan counts re-run in the worktree.

Fixes CL-10649

[linear-code]

CL-10649

[corbits-triage]

Triage: Pass

No changes needed from you. A maintainer will review this pull request.

[TheGreatAxios]

Findings moved to a Linear implementation doc (https://linear.app/abklabs/document/tui-pre-060-compat-spike-cl-10649-decision-record-1104b83309f3) rather than a checked-in doc; closing in favor of proceeding directly to the staged bump. Branch and worktree are being removed.