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fix(agent-edit-v2): detect live ref drift against persisted base not live fallback #62

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fix(agent-edit-v2): detect live ref drift against persisted base not live fallback #62

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48a7abd
fix(agent-edit-v2): detect live ref drift against persisted base not …
devYRPauli Jun 20, 2026
d7dadc8
fix(agent-edit-v2): gate the persisted drift baseline on baseRevision
devYRPauli Jul 15, 2026
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17 changes: 16 additions & 1 deletion server/agent-edit-v2.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -867,7 +867,22 @@ export async function applyAgentEditV2(
const usingAuthoritativeFallback = authoritativeBase.base.source === 'live_yjs'
|| authoritativeMarkdown !== stripEphemeralCollabSpans(doc.markdown ?? '');
if (usingAuthoritativeFallback) {
const persistedBase = parseMarkdownWithHtmlFallback(parser, stripEphemeralCollabSpans(doc.markdown ?? ''));
// The b1..bN refs the agent sent were assigned against the base it declared. For a
// baseRevision-only edit that base is the persisted document row at that revision.
// doc.markdown here is the live-fallback canonical read, so using it would compare the
// live authoritative fragment against itself and never detect that a concurrent edit
// shifted block topology under the agent's refs. Use the persisted row as the drift
// baseline. When a baseToken is supplied the agent opted into the live base directly
// (validated above), so that base is already the correct comparison frame.
const persistedDriftBaseline = baseToken ? null : getDocumentBySlug(slug);
const driftBaselineMarkdown = baseToken
? stripEphemeralCollabSpans(doc.markdown ?? '')
: stripEphemeralCollabSpans(
persistedDriftBaseline?.revision === baseRevision
? persistedDriftBaseline.markdown
: doc.markdown ?? '',
);
const persistedBase = parseMarkdownWithHtmlFallback(parser, driftBaselineMarkdown);
if (!persistedBase.doc) {
return {
status: 500,
Expand Down