docs: establish pre-alpha clean-cutover policy

AGENTS.md

@@ -0,0 +1,5 @@
+# Compatibility
+
+Vamp is a single-user, pre-alpha tool. Prefer clean cutovers to the simplest current design across code, configuration, interfaces, and persisted formats. Update callers and remove obsolete paths together; add backwards compatibility or migrations only when explicitly requested.
+
+Report incompatible persisted data clearly and preserve it unless the user explicitly requests a reset or deletion.

TODO.md

@@ -6,14 +6,12 @@
 	- save and reopen reviews using local files that coding agents can read; no server or client/server protocol.
 	- anchor comments to immutable revision IDs, paths, sides, and source line ranges, never screen coordinates or mutable file indices.
 	- preserve original anchors and mark comments stale when the reviewed snapshot no longer matches; defer automatic reanchoring.
-- [ ] add an option for three pane lef/base/right view for conflict resolution.
-    - alternative pane layout as left/right with base underneath (configurable)
 - [x] diff view: attach local review comments to arbitrary contiguous text ranges, not only containing lines.
 	- preserve exact start/end source positions in grapheme coordinates with an exclusive end, including partial-line and multiline selections on either diff side.
 	- characterwise Visual (`v`) anchors the exact selected text; Visual Line (`V`) anchors whole selected lines; no selection retains current-line behavior.
 	- retain gutter markers for discovery and highlight the exact anchored text when its comment is selected.
 	- preserve immutable snapshot identity and existing stale detection; never silently reanchor comments after source changes.
-	- persist precise ranges in version 2 JSON import/export; no backwards compatibility with old review formats. SQLite storage follows in the next item.
+	- persist precise ranges in version 2 JSON import/export. SQLite storage follows in the next item.
 	- future GitHub publishing may map precise local anchors to supported line ranges without reducing precision in the local review.
 - [ ] persist local reviews automatically in a local SQLite database using rusqlite; no server, hosted storage, or synchronization.
    - keep one database under $XDG_DATA_HOME/vamp/reviews/, falling back to ~/.local/share/vamp/reviews/; allow a configurable review_directory.
@@ -21,9 +19,11 @@
    - autosave committed comment edits and summaries when dismissing or switching review editors; save verdicts and deletions immediately, using transactions rather than per-keystroke writes.
    - automatically reopen the repository's sole review; offer a selector when several exist.
    - retain explicit JSON export/import for sharing with coding agents; export must not redirect subsequent autosaves away from the database.
-   - version the database schema and migrate it safely; use review-version checks to reject conflicting edits from multiple editor instances.
+   - version the database schema; use review-version checks to reject conflicting edits from multiple editor instances.
    - surface write failures and conflicts without discarding drafts or marking unsuccessful saves as persisted.
    - persist the precise start/end grapheme anchors without reducing them to line ranges.
+- [ ] add an option for three pane lef/base/right view for conflict resolution.
+    - alternative pane layout as left/right with base underneath (configurable)
 - [ ] diff view: GitHub code review integration after the local review UX is usable.
 	- publish local reviews explicitly: general PR comments, inline line/range comments, review summaries, approval, and requests for changes.
 	- preserve explicit PR identity and reviewed commit IDs; validate anchors against GitHub's PR diff and recheck the PR head before submission.