F3 SLICE-3/4 review fixes: counted self-writes, persist deletion-to-empty, render all visible editors (#6)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/store.ts

@@ -11,19 +11,33 @@ import * as path from "node:path";
 import { emptyArtifact, serializeArtifact, type Artifact } from "./model";
 
 export class CoauthorStore {
-  /** sidecar paths this store just wrote, so the shared watcher can ignore them. */
-  private readonly selfWrites = new Set<string>();
+  /**
+   * Pending-write counts keyed by absolute sidecar path. A Map (not Set) because
+   * one doc save can trigger TWO store.update() calls (ThreadController then
+   * AttributionController), both writing the same sidecar — a Set would let the
+   * second watcher event leak through as "external" (comment-UI flicker).
+   */
+  private readonly selfWrites = new Map<string, number>();
 
   /** @param rootDir absolute workspace-folder root that owns the `.threads/` tree. */
   constructor(private readonly rootDir: string) {}
 
   /**
-   * Delete-and-report: true iff `fsPath` was a sidecar we just wrote via
-   * `update`. The shared watcher (extension.ts) calls this to suppress
-   * self-write events before fanning out to the controllers.
+   * Decrement-and-report: true iff `fsPath` was a sidecar this store just
+   * wrote via `update`. Each successful `update` increments the counter once;
+   * each call here decrements it (deleting the key at zero). The shared watcher
+   * (extension.ts) calls this to suppress self-write events before fanning out
+   * to the controllers.
    */
   consumeSelfWrite(fsPath: string): boolean {
-    return this.selfWrites.delete(fsPath);
+    const count = this.selfWrites.get(fsPath);
+    if (!count) return false;
+    if (count === 1) {
+      this.selfWrites.delete(fsPath);
+    } else {
+      this.selfWrites.set(fsPath, count - 1);
+    }
+    return true;
   }
 
   /** `.threads/<repo-relative-docPath>.json` (spec §6.3). */
@@ -61,8 +75,12 @@ export class CoauthorStore {
     for (const id of Object.keys(artifact.anchors)) {
       if (!referenced.has(id)) delete artifact.anchors[id];
     }
-    this.selfWrites.add(this.sidecarPath(docPath));
     this.save(docPath, artifact);
+    // Increment AFTER the synchronous write: fs.writeFileSync completes before
+    // this line executes, and watcher events are delivered async, so marking
+    // post-write is race-free for suppression purposes.
+    const p = this.sidecarPath(docPath);
+    this.selfWrites.set(p, (this.selfWrites.get(p) ?? 0) + 1);
     return artifact;
   }
 }