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F3 hardening: observable seam misses, cheaper disk-compare, E2E ordering notes (#6)

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Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
This commit is contained in:
Ben Stull
2026-06-10 11:00:28 -07:00
parent fc5fde1cc9
commit 41b1cb4f3b
4 changed files with 49 additions and 6 deletions
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src/attributionController.ts
+30 -3
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@@ -169,10 +169,24 @@ export class AttributionController implements vscode.Disposable {
this.render(e.document);
}
/** True when the document buffer is byte-identical to the file on disk. */
/**
* True when the document buffer is byte-identical to the file on disk.
* Fires only on `!isDirty` change events — first change after every clean
* state (frequent under `files.autoSave: afterDelay`) and reverts/reloads;
* O(file size) sync read. A size pre-check avoids the full read in the
* common case: if the byte lengths differ (accounting for a possible 3-byte
* UTF-8 BOM that `document.getText()` never includes) we return early. When
* a BOM is present the disk read is stripped before comparing so a genuine
* revert does not clobber attribution.
*/
private matchesDisk(document: vscode.TextDocument): boolean {
try {
return fs.readFileSync(document.uri.fsPath, "utf8") === document.getText();
const bufLen = Buffer.byteLength(document.getText(), "utf8");
const stat = fs.statSync(document.uri.fsPath);
// Allow size === bufLen (no BOM) OR size === bufLen + 3 (UTF-8 BOM).
if (stat.size !== bufLen && stat.size !== bufLen + 3) return false;
const disk = fs.readFileSync(document.uri.fsPath, "utf8").replace(/^/, "");
return disk === document.getText();
} catch {
// Unreadable/missing file: treat as a real edit (attribute), per
// fail-open honesty — misclassifying a sync as an edit is recoverable.
@@ -190,6 +204,8 @@ export class AttributionController implements vscode.Disposable {
* `match` already consumed it), so a no-op edit never leaks a registration.
* The replace is self-minimized (common prefix/suffix trimmed) to mirror the
* host's WorkspaceEdit diff-minimization, so registered == applied == delivered.
* Callers issuing concurrent edits on the same document must serialize them or
* pass `expectedVersion` (offsets are computed against the call-time snapshot).
*/
async applyAgentEdit(
document: vscode.TextDocument,
@@ -225,7 +241,18 @@ export class AttributionController implements vscode.Disposable {
const we = new vscode.WorkspaceEdit();
we.replace(document.uri, new vscode.Range(document.positionAt(minStart), document.positionAt(minEnd)), minText);
const ok = await vscode.workspace.applyEdit(we);
this.pending.unregister(pendingEdit);
const removed = this.pending.unregister(pendingEdit);
if (ok && removed) {
// workspace.applyEdit resolves AFTER onDidChangeTextDocument is dispatched
// synchronously to listeners, so a matching change event should have already
// consumed the registration before we reach here. If it is still present,
// the host minimized the diff differently than we predicted — attribution
// may be wrong for this edit (INV-9).
this.output.appendLine(
"WARN: seam edit applied but its change event never matched the registration " +
"(host minimized differently?) — the edit may be mis-attributed (INV-9).",
);
}
return ok;
}