Why: rollback eligibility was implicit (any struct with a mark field),
restore followed symlinks out of the root, a single failing file
aborted the rewind leaving unreported partial state, and the log grew
unboundedly with an O(N) read per record.
Evidence: GOWORK=off go vet + go test -count=1 ./... green;
TestCheckpointedToolSetIsPinned (eligibility is exactly
{write_file, edit_file, multi_edit}), TestRewindSkipsSymlinkTarget
(link and outside target untouched, classified Skipped),
TestRewindPartialFailureContinues (Failed reported, rest restored),
TestCompactKeepsRecentAnchors (original seqs kept, monotonic after),
plus pinned edges for empty ordered, identical-rewrite=Already, and
per-record roots; all pre-existing rewind tests pass unchanged.
Impact: Result gains Failed (additive); Rewind no longer aborts on a
single file; symlinks classify as external changes; Compact bounds the
log; Seq is computed from a cached counter instead of a full read.
Refs: Agent-System-Documents#43 (N3 plan WP3)
Why: a crash after a tool was about to run left the call unpaired, and workspace writes could not be rewound.
Evidence: GOWORK=off go test ./runtime/ ./runtime/llm/ ./runtime/checkpoint/ ./runtime/telemetry/ ./runtime/tools/ ./runtime/session/ ./adapters/native/
Impact: pending calls rerun only when both the stored and current replay declarations are safe; otherwise the result is an error. Empty fallback lists and a nil checkpoint log keep the previous behavior.
Refs: feature/durable-rewind
Co-authored-by: Cursor <cursoragent@cursor.com>
weichen
