Stop transient file conflict callouts (#2694)

* fix(app): prevent transient file conflict callouts

Watcher versions are candidates until a matching disk read settles them. The editor now classifies the settled bytes once, preserving dirty buffers and keeping reload content paired with its revision.

* fix(app): preserve external BOM changes

packages/app/e2e/file-change-conflicts.spec.ts

@@ -4,6 +4,11 @@ import { expect, test, type Page } from "./fixtures";
 import { expectFileTabOpen, openFileExplorer, openFileFromExplorer } from "./helpers/file-explorer";
 import type { WithWorkspace } from "./helpers/with-workspace";
 import { installDaemonWebSocketGate } from "./helpers/daemon-websocket-gate";
+import {
+  expectFileCalloutWasRendered,
+  expectNoFileCalloutWasRendered,
+  recordFileCallouts,
+} from "./helpers/file-callouts";
 
 function visibleEditor(page: Page) {
   return page.getByTestId("file-source-editor").filter({ visible: true }).locator(".cm-content");
@@ -61,10 +66,11 @@ async function replaceFileAfterDeletionWasObserved(input: {
   gate.holdFileReads(relativePath);
   await unlink(filePath);
   await gate.waitForHeldFileRead();
+  await expect(fileCallout(page)).toHaveCount(0);
+  gate.releaseHeldFileRead();
   await expectOnlyFileCallout(page, "File deleted on disk");
   gate.holdNextReadyFileUpdate(relativePath);
   await writeFile(filePath, content, "utf8");
-  gate.releaseHeldFileRead();
   await gate.waitForHeldReadyFileUpdate();
   await expect.poll(() => readFile(filePath, "utf8")).toBe(content);
 }
@@ -103,7 +109,96 @@ async function expectDirtyConflictCanReload(page: Page): Promise<void> {
   await expect(fileCallout(page)).toHaveCount(0);
 }
 
+async function restoreFileAfterWatcherObservedTemporaryAbsence(input: {
+  gate: Awaited<ReturnType<typeof installDaemonWebSocketGate>>;
+  filePath: string;
+  relativePath: string;
+}): Promise<void> {
+  const parkedPath = `${input.filePath}.saving`;
+  input.gate.holdFileReads(input.relativePath);
+  await rename(input.filePath, parkedPath);
+  await input.gate.waitForFileUpdate(input.relativePath, "missing");
+  await input.gate.waitForHeldFileRead();
+  await writeFile(input.filePath, await readFile(parkedPath));
+  await unlink(parkedPath);
+  input.gate.releaseHeldFileRead();
+}
+
 test.describe("Workspace file change conflicts", () => {
+  test("a temporary write gap never renders a disk-change callout", async ({
+    page,
+    withWorkspace,
+  }) => {
+    const gate = await installDaemonWebSocketGate(page);
+    const relativePath = "temporary-gap.ts";
+    const filePath = await openTrackedFile(page, withWorkspace, {
+      prefix: "file-temporary-gap-",
+      relativePath,
+      content: "const preserved = true;\n",
+    });
+    await gate.waitForFileSubscription(relativePath);
+    await recordFileCallouts(page);
+
+    await restoreFileAfterWatcherObservedTemporaryAbsence({ gate, filePath, relativePath });
+    await replaceEditorText(page, "const local = true;\n");
+
+    await expect.poll(() => readFile(filePath, "utf8")).toContain("const local = true;");
+    await expect(fileCallout(page)).toHaveCount(0);
+    await expectNoFileCalloutWasRendered(page);
+  });
+
+  test("an identical atomic rewrite never renders a disk-change callout", async ({
+    page,
+    withWorkspace,
+  }) => {
+    const gate = await installDaemonWebSocketGate(page);
+    const relativePath = "identical-rewrite.ts";
+    const content = "const preserved = true;\n";
+    const filePath = await openTrackedFile(page, withWorkspace, {
+      prefix: "file-identical-rewrite-",
+      relativePath,
+      content,
+    });
+    await gate.waitForFileSubscription(relativePath);
+    await recordFileCallouts(page);
+
+    gate.holdNextReadyFileUpdate(relativePath);
+    await writeFile(`${filePath}.tmp`, content, "utf8");
+    await rename(`${filePath}.tmp`, filePath);
+    await gate.waitForHeldReadyFileUpdate();
+    await replaceEditorText(page, "const local = true;\n");
+    gate.releaseHeldReadyFileUpdate();
+
+    await expect.poll(() => readFile(filePath, "utf8")).toContain("const local = true;");
+    await expect(fileCallout(page)).toHaveCount(0);
+    await expectNoFileCalloutWasRendered(page);
+  });
+
+  test("a save watcher refresh never replays the pre-save buffer", async ({
+    page,
+    withWorkspace,
+  }) => {
+    const gate = await installDaemonWebSocketGate(page);
+    const relativePath = "save-refresh.ts";
+    const filePath = await openTrackedFile(page, withWorkspace, {
+      prefix: "file-save-refresh-",
+      relativePath,
+      content: "const before = true;\n",
+    });
+    await gate.waitForFileSubscription(relativePath);
+    await recordFileCallouts(page);
+    gate.holdFileReads(relativePath);
+
+    await replaceEditorText(page, "const saved = true;\n");
+    await expect.poll(() => readFile(filePath, "utf8")).toContain("const saved = true;");
+    await gate.waitForHeldFileRead();
+
+    await expect(visibleEditor(page)).toContainText("const saved = true;");
+    await expect(fileCallout(page)).toHaveCount(0);
+    await expectNoFileCalloutWasRendered(page);
+    gate.releaseHeldFileRead();
+  });
+
   test("a clean file replaced on disk offers one working reload action", async ({
     page,
     withWorkspace,
@@ -122,8 +217,8 @@ test.describe("Workspace file change conflicts", () => {
       relativePath: "inventory.md",
       content: "# After\n",
     });
-    await expectCleanReplacementCanReload(page);
     gate.releaseHeldReadyFileUpdate();
+    await expectCleanReplacementCanReload(page);
   });
 
   test("a deleted file shows one explanatory notice and no resolution actions", async ({
@@ -136,8 +231,10 @@ test.describe("Workspace file change conflicts", () => {
       content: "# Present\n",
     });
     await expect(filePane(page).getByText("Present", { exact: true })).toBeVisible();
+    await recordFileCallouts(page);
     await unlink(filePath);
     await expectDeletedFileNotice(page);
+    await expectFileCalloutWasRendered(page, "File deleted on disk");
   });
 
   test("a file check error offers a working retry", async ({ page, withWorkspace }) => {

packages/app/e2e/helpers/daemon-websocket-gate.ts

@@ -76,6 +76,8 @@ export async function installDaemonWebSocketGate(page: Page) {
   const clientRequestCounts = new Map<string, number>();
   const subscribedFilePaths = new Set<string>();
   const fileSubscriptionWaiters = new Map<string, () => void>();
+  const observedFileUpdates = new Set<string>();
+  const fileUpdateWaiters = new Map<string, () => void>();
   let fileReadPathToHold: string | null = null;
   let heldFileReads: Array<() => void> = [];
   let resolveHeldFileRead: (() => void) | null = null;
@@ -84,6 +86,19 @@ export async function installDaemonWebSocketGate(page: Page) {
   let heldReadyFileUpdate: (() => void) | null = null;
   let resolveHeldReadyFileUpdate: (() => void) | null = null;
   let heldReadyFileUpdatePromise = Promise.resolve();
+  const recordFileUpdate = (message: ServerMessage): void => {
+    if (
+      message.type !== "fs.file.update" ||
+      typeof message.payload?.version?.status !== "string" ||
+      typeof message.payload.version.path !== "string"
+    ) {
+      return;
+    }
+    const key = `${message.payload.version.path}:${message.payload.version.status}`;
+    observedFileUpdates.add(key);
+    fileUpdateWaiters.get(key)?.();
+    fileUpdateWaiters.delete(key);
+  };
 
   await page.routeWebSocket(daemonWsRoutePattern(), (ws) => {
     if (!acceptingConnections) {
@@ -134,6 +149,7 @@ export async function installDaemonWebSocketGate(page: Page) {
         fileSubscriptionWaiters.get(path)?.();
         fileSubscriptionWaiters.delete(path);
       }
+      if (serverMessage) recordFileUpdate(serverMessage);
       if (
         serverMessage?.type === "fs.file.update" &&
         serverMessage.payload?.version?.status === "ready" &&
@@ -157,6 +173,11 @@ export async function installDaemonWebSocketGate(page: Page) {
       if (subscribedFilePaths.has(path)) return Promise.resolve();
       return new Promise((resolve) => fileSubscriptionWaiters.set(path, resolve));
     },
+    waitForFileUpdate(path: string, status: "ready" | "missing" | "error"): Promise<void> {
+      const key = `${path}:${status}`;
+      if (observedFileUpdates.has(key)) return Promise.resolve();
+      return new Promise((resolve) => fileUpdateWaiters.set(key, resolve));
+    },
     holdFileReads(path: string): void {
       fileReadPathToHold = path;
       heldFileReads = [];

packages/app/e2e/helpers/file-callouts.ts

@@ -0,0 +1,48 @@
+import type { Page } from "@playwright/test";
+import { expect } from "../fixtures";
+
+export async function recordFileCallouts(page: Page): Promise<void> {
+  await page.evaluate(() => {
+    const callouts: string[] = [];
+    const recordAlert = (alert: Element) => {
+      const text = alert.textContent?.trim();
+      if (text && !callouts.includes(text)) callouts.push(text);
+    };
+    const record = (records: MutationRecord[]) => {
+      for (const mutation of records) {
+        if (
+          !(mutation.target instanceof Element) ||
+          !mutation.target.closest('[data-testid="workspace-file-pane"]')
+        ) {
+          continue;
+        }
+        for (const node of mutation.addedNodes) {
+          if (!(node instanceof Element)) continue;
+          if (node.matches('[role="alert"]')) recordAlert(node);
+          for (const alert of node.querySelectorAll('[role="alert"]')) recordAlert(alert);
+        }
+      }
+    };
+    const observer = new MutationObserver(record);
+    observer.observe(document.body, { childList: true, subtree: true, characterData: true });
+    Object.assign(globalThis, { __PASEO_RECORDED_FILE_CALLOUTS__: callouts });
+  });
+}
+
+export async function expectFileCalloutWasRendered(page: Page, title: string): Promise<void> {
+  await expect
+    .poll(() => recordedFileCallouts(page))
+    .toEqual(expect.arrayContaining([expect.stringContaining(title)]));
+}
+
+export async function expectNoFileCalloutWasRendered(page: Page): Promise<void> {
+  await expect.poll(() => recordedFileCallouts(page)).toEqual([]);
+}
+
+function recordedFileCallouts(page: Page): Promise<string[]> {
+  return page.evaluate(
+    () =>
+      (globalThis as typeof globalThis & { __PASEO_RECORDED_FILE_CALLOUTS__?: string[] })
+        .__PASEO_RECORDED_FILE_CALLOUTS__ ?? [],
+  );
+}

packages/app/src/file-explorer/read-result.ts

@@ -12,6 +12,7 @@ export function explorerFileFromReadResult(file: FileReadResult): ExplorerFile {
     mimeType: file.mime,
     size: file.size,
     modifiedAt: file.modifiedAt,
+    revision: file.revision,
   };
 }
 

packages/app/src/file-pane/editor/model.test.ts

@@ -5,7 +5,9 @@ import {
   getFileConflictCallout,
   type FileEditorClock,
   type FileEditorFile,
+  type FileEditorObservation,
   type FileEditorSession,
+  type FileObservationSource,
 } from "./model";
 
 class TestClock implements FileEditorClock {
@@ -38,10 +40,6 @@ class FileSession implements FileEditorSession {
     this.file = file;
   }
 
-  async read(): Promise<FileEditorFile> {
-    return this.file;
-  }
-
   async write(input: {
     content: string;
     expectedModifiedAt: string;
@@ -71,6 +69,34 @@ class FileSession implements FileEditorSession {
   }
 }
 
+class ObservationSource implements FileObservationSource {
+  observation: FileEditorObservation | null;
+  refreshes = 0;
+  private readonly listeners = new Set<() => void>();
+
+  constructor(observation: FileEditorObservation | null) {
+    this.observation = observation;
+  }
+
+  subscribe(listener: () => void): () => void {
+    this.listeners.add(listener);
+    return () => this.listeners.delete(listener);
+  }
+
+  getObservation(): FileEditorObservation | null {
+    return this.observation;
+  }
+
+  refresh = (): void => {
+    this.refreshes += 1;
+  };
+
+  emit(observation: FileEditorObservation): void {
+    this.observation = observation;
+    for (const listener of this.listeners) listener();
+  }
+}
+
 function ready(
   modifiedAt = "2026-07-18T00:00:00.000Z",
   size = 3,
@@ -94,6 +120,14 @@ function makeModel(input: MakeModelInput = {}) {
   return { model: new FileEditorModel({ file, session, clock }), session, clock };
 }
 
+function observeFile(model: FileEditorModel, file: FileEditorFile): void {
+  model.receiveFileObservation({ status: "ready", file });
+}
+
+function observeVersion(model: FileEditorModel, version: FileEditorObservation): void {
+  model.receiveFileObservation(version);
+}
+
 describe("FileEditorModel", () => {
   test("tracks whether the current buffer differs from persisted content", async () => {
     const { model } = makeModel();
@@ -112,11 +146,194 @@ describe("FileEditorModel", () => {
   test("adopts a precise revision for otherwise unchanged initial metadata", () => {
     const { model } = makeModel();
 
-    model.receiveFileVersion({ ...ready(), revision: "precise-revision" });
+    observeFile(model, {
+      content: "one",
+      hasBom: false,
+      version: { ...ready(), revision: "precise-revision" },
+    });
 
     expect(model.getSnapshot().observedVersion).toMatchObject({ revision: "precise-revision" });
   });
 
+  test("adopts an unchanged disk revision without disturbing a dirty buffer", async () => {
+    const { model, session } = makeModel();
+    model.edit("local");
+    observeFile(model, {
+      content: "one",
+      hasBom: false,
+      version: { ...ready(), revision: "replacement-revision" },
+    });
+
+    expect(model.getSnapshot()).toMatchObject({ status: "dirty", content: "local" });
+    await model.save();
+
+    expect(session.writes).toEqual([
+      {
+        content: "local",
+        expectedModifiedAt: "2026-07-18T00:00:00.000Z",
+        expectedRevision: "replacement-revision",
+      },
+    ]);
+  });
+
+  test("adopts an external BOM change before saving a dirty buffer", async () => {
+    const { model, session } = makeModel();
+    model.edit("local");
+    observeFile(model, {
+      content: "one",
+      hasBom: true,
+      version: { ...ready(), revision: "replacement-revision" },
+    });
+
+    await model.save();
+
+    expect(session.writes).toEqual([
+      {
+        content: "\uFEFFlocal",
+        expectedModifiedAt: "2026-07-18T00:00:00.000Z",
+        expectedRevision: "replacement-revision",
+      },
+    ]);
+  });
+
+  test("conflicts when a same-content observation changes the BOM during a save", async () => {
+    const { model, session } = makeModel();
+    session.holdNextWrite();
+    model.edit("saved");
+    const save = model.save();
+    observeFile(model, {
+      content: "saved",
+      hasBom: true,
+      version: ready("2026-07-18T00:00:02.000Z", 6),
+    });
+    session.finishHeldWrite({
+      status: "written",
+      modifiedAt: "2026-07-18T00:00:01.000Z",
+      size: 5,
+    });
+
+    await save;
+
+    expect(model.getSnapshot()).toMatchObject({
+      status: "conflict",
+      observedVersion: { modifiedAt: "2026-07-18T00:00:02.000Z" },
+    });
+  });
+
+  test("ignores a settled observation that was already consumed", () => {
+    const { model } = makeModel();
+    const observation: FileEditorObservation = {
+      status: "ready",
+      file: { content: "one", hasBom: false, version: ready() },
+    };
+    let emissions = 0;
+    model.subscribe(() => {
+      emissions += 1;
+    });
+    model.receiveFileObservation(observation);
+    const emissionsAfterFirstDelivery = emissions;
+
+    model.receiveFileObservation(observation);
+
+    expect(emissions).toBe(emissionsAfterFirstDelivery);
+  });
+
+  test("does not replay the pre-save observation while its refresh is pending", async () => {
+    const { model } = makeModel();
+    const observation: FileEditorObservation = {
+      status: "ready",
+      file: { content: "one", hasBom: false, version: ready() },
+    };
+    model.receiveFileObservation(observation);
+    model.edit("saved");
+    await model.save();
+
+    model.receiveFileObservation(observation);
+
+    expect(model.getSnapshot()).toMatchObject({ status: "clean", content: "saved" });
+  });
+
+  test("does not reload stale bytes after a write conflict", async () => {
+    const { model, session } = makeModel();
+    session.nextWrite = {
+      status: "conflict",
+      version: ready("2026-07-18T00:00:02.000Z", 8),
+    };
+    model.edit("important local work");
+    await model.save();
+
+    await model.reload();
+
+    expect(model.getSnapshot()).toMatchObject({
+      status: "conflict",
+      content: "important local work",
+      observedVersion: { modifiedAt: "2026-07-18T00:00:02.000Z" },
+    });
+  });
+
+  test("reloads a write conflict only after refreshed bytes arrive", async () => {
+    const { model, session } = makeModel();
+    const source = new ObservationSource({
+      status: "ready",
+      file: { content: "one", hasBom: false, version: ready() },
+    });
+    model.connectFileObservations(source);
+    session.nextWrite = {
+      status: "conflict",
+      version: ready("2026-07-18T00:00:02.000Z", 4),
+    };
+    model.edit("local");
+    await model.save();
+
+    await model.reload();
+    expect(source.refreshes).toBe(1);
+    expect(model.getSnapshot().content).toBe("local");
+    source.emit({
+      status: "ready",
+      file: {
+        content: "disk",
+        hasBom: false,
+        version: ready("2026-07-18T00:00:02.000Z", 4),
+      },
+    });
+
+    expect(model.getSnapshot()).toMatchObject({ status: "clean", content: "disk" });
+  });
+
+  test("abandons a deferred reload when its refresh fails", async () => {
+    const { model, session } = makeModel();
+    const source = new ObservationSource({
+      status: "ready",
+      file: { content: "one", hasBom: false, version: ready() },
+    });
+    model.connectFileObservations(source);
+    session.nextWrite = {
+      status: "conflict",
+      version: ready("2026-07-18T00:00:02.000Z", 4),
+    };
+    model.edit("local");
+    await model.save();
+    await model.reload();
+    source.emit({
+      status: "error",
+      cwd: "/workspace",
+      path: "file.ts",
+      error: "File unavailable.",
+    });
+    model.edit("new local work");
+
+    source.emit({
+      status: "ready",
+      file: {
+        content: "disk",
+        hasBom: false,
+        version: ready("2026-07-18T00:00:03.000Z", 4),
+      },
+    });
+
+    expect(model.getSnapshot()).toMatchObject({ status: "conflict", content: "new local work" });
+  });
+
   test("keeps a newer edit modified when an older save finishes", async () => {
     const { model, session } = makeModel();
     session.holdNextWrite();
@@ -204,8 +421,7 @@ describe("FileEditorModel", () => {
       version: ready("2026-07-18T00:00:02.000Z", 8) as Extract<FileVersion, { status: "ready" }>,
     };
 
-    model.receiveFileVersion(session.file.version);
-    await Promise.resolve();
+    observeFile(model, session.file);
 
     expect(model.getSnapshot()).toMatchObject({ status: "clean", content: "external" });
   });
@@ -218,8 +434,7 @@ describe("FileEditorModel", () => {
       version: ready("2026-07-18T00:00:02.000Z", 7) as Extract<FileVersion, { status: "ready" }>,
     };
 
-    model.receiveFileVersion(session.file.version);
-    await Promise.resolve();
+    observeFile(model, session.file);
     expect(model.getSnapshot().lineSeparator).toBe("\n");
     model.edit("saved\n");
     await model.save();
@@ -230,19 +445,13 @@ describe("FileEditorModel", () => {
     });
   });
 
-  test("coalesces consecutive clean disk updates onto the latest reload", async () => {
-    const { model, session } = makeModel();
-    const reads: Array<(file: FileEditorFile) => void> = [];
-    session.read = () => new Promise((resolve) => reads.push(resolve));
+  test("applies consecutive clean disk observations", () => {
+    const { model } = makeModel();
     const firstVersion = ready("2026-07-18T00:00:02.000Z", 5);
     const latestVersion = ready("2026-07-18T00:00:03.000Z", 6);
 
-    model.receiveFileVersion(firstVersion);
-    model.receiveFileVersion(latestVersion);
-    reads[0]?.({ content: "first", hasBom: false, version: firstVersion });
-    await Promise.resolve();
-    reads[1]?.({ content: "latest", hasBom: false, version: latestVersion });
-    await Promise.resolve();
+    observeFile(model, { content: "first", hasBom: false, version: firstVersion });
+    observeFile(model, { content: "latest", hasBom: false, version: latestVersion });
 
     expect(model.getSnapshot()).toMatchObject({ status: "clean", content: "latest" });
   });
@@ -250,7 +459,11 @@ describe("FileEditorModel", () => {
   test("preserves a dirty buffer and overwrites against the newest disk revision", async () => {
     const { model, session } = makeModel();
     model.edit("local");
-    model.receiveFileVersion(ready("2026-07-18T00:00:02.000Z", 4));
+    observeFile(model, {
+      content: "disk",
+      hasBom: false,
+      version: ready("2026-07-18T00:00:02.000Z", 4),
+    });
 
     expect(model.getSnapshot()).toMatchObject({ status: "conflict", content: "local" });
     await model.overwrite();
@@ -264,7 +477,11 @@ describe("FileEditorModel", () => {
   test("keeps the local CRLF and BOM when overwriting a conflict", async () => {
     const { model, session } = makeModel({ content: "one\r\n", hasBom: true });
     model.edit("local\r\n");
-    model.receiveFileVersion(ready("2026-07-18T00:00:02.000Z", 4));
+    observeFile(model, {
+      content: "disk",
+      hasBom: false,
+      version: ready("2026-07-18T00:00:02.000Z", 4),
+    });
 
     await model.overwrite();
 
@@ -284,7 +501,7 @@ describe("FileEditorModel", () => {
       { status: "ready" }
     >;
     session.file = { content: "disk", hasBom: false, version: diskVersion };
-    model.receiveFileVersion(diskVersion);
+    observeFile(model, session.file);
 
     await model.reload();
 
@@ -299,7 +516,7 @@ describe("FileEditorModel", () => {
       { status: "ready" }
     >;
     session.file = { content: "disk\n", hasBom: false, version: diskVersion };
-    model.receiveFileVersion(diskVersion);
+    observeFile(model, session.file);
 
     await model.reload();
     model.edit("saved\n");
@@ -328,7 +545,7 @@ describe("FileEditorModel", () => {
   test("a deletion conflicts with local changes and stops autosave", () => {
     const { model, session, clock } = makeModel();
     model.edit("local");
-    model.receiveFileVersion({ status: "missing", cwd: "/workspace", path: "file.ts" });
+    observeVersion(model, { status: "missing", cwd: "/workspace", path: "file.ts" });
 
     clock.fire();
 
@@ -338,14 +555,14 @@ describe("FileEditorModel", () => {
 
   test("clears a transient check error when the recovered file is unchanged", () => {
     const { model } = makeModel();
-    model.receiveFileVersion({
+    observeVersion(model, {
       status: "error",
       cwd: "/workspace",
       path: "file.ts",
       error: "Requested path is not a file",
     });
 
-    model.receiveFileVersion(ready());
+    observeFile(model, { content: "one", hasBom: false, version: ready() });
 
     expect(model.getSnapshot()).toMatchObject({
       status: "clean",
@@ -358,14 +575,14 @@ describe("FileEditorModel", () => {
   test("resumes autosave when a dirty file recovers unchanged from a check error", async () => {
     const { model, session, clock } = makeModel();
     model.edit("local");
-    model.receiveFileVersion({
+    observeVersion(model, {
       status: "error",
       cwd: "/workspace",
       path: "file.ts",
       error: "Requested path is not a file",
     });
 
-    model.receiveFileVersion(ready());
+    observeFile(model, { content: "one", hasBom: false, version: ready() });
     clock.fire();
     await Promise.resolve();
 

packages/app/src/file-pane/editor/model.ts

@@ -1,6 +1,6 @@
 import type { FileVersion, FileWriteResult } from "@getpaseo/protocol/messages";
 
-export type FileEditorStatus = "loading" | "clean" | "dirty" | "saving" | "conflict" | "error";
+export type FileEditorStatus = "clean" | "dirty" | "saving" | "conflict" | "error";
 export type FileLineSeparator = "\n" | "\r\n" | "\r";
 
 export interface FileEditorSnapshot {
@@ -25,7 +25,6 @@ export interface FileEditorFile {
 }
 
 export interface FileEditorSession {
-  read(): Promise<FileEditorFile>;
   write(input: {
     content: string;
     expectedModifiedAt: string;
@@ -33,11 +32,18 @@ export interface FileEditorSession {
   }): Promise<FileWriteResult>;
 }
 
-export interface FileVersionSource {
+export type FileEditorObservation =
+  | { status: "ready"; file: FileEditorFile }
+  | Extract<FileVersion, { status: "missing" | "error" }>;
+
+export interface FileObservationSource {
   subscribe(listener: () => void): () => void;
-  getVersion(): FileVersion | null;
+  getObservation(): FileEditorObservation | null;
+  refresh(): void;
 }
 
+type ObservedDiskState = FileEditorObservation | { status: "unsettled"; version: FileVersion };
+
 export interface FileEditorClock {
   setTimeout(callback: () => void, delayMs: number): ReturnType<typeof setTimeout>;
   clearTimeout(handle: ReturnType<typeof setTimeout>): void;
@@ -60,10 +66,14 @@ export class FileEditorModel {
   private autosave: ReturnType<typeof setTimeout> | null = null;
   private saveSequence = 0;
   private disposed = false;
-  private observedWhileSaving: FileVersion | null = null;
+  private observedWhileSaving: FileEditorObservation | null = null;
+  private observed: ObservedDiskState;
+  private lastReceivedObservation: FileEditorObservation | null = null;
+  private refreshObservation: (() => void) | null = null;
+  private reloadRequested = false;
   private persistedContent: string;
   private hasBom: boolean;
-  private unsubscribeVersionSource: (() => void) | null = null;
+  private unsubscribeObservationSource: (() => void) | null = null;
 
   constructor(input: {
     file: FileEditorFile;
@@ -74,6 +84,7 @@ export class FileEditorModel {
     this.clock = input.clock ?? systemClock;
     this.persistedContent = input.file.content;
     this.hasBom = input.file.hasBom;
+    this.observed = { status: "ready", file: input.file };
     this.snapshot = {
       status: "clean",
       content: input.file.content,
@@ -92,26 +103,29 @@ export class FileEditorModel {
 
   getSnapshot = (): FileEditorSnapshot => this.snapshot;
 
-  connectFileVersions(source: FileVersionSource): void {
-    this.disconnectFileVersions();
-    const receiveVersion = () => {
-      const version = source.getVersion();
-      if (version) this.receiveFileVersion(version);
+  connectFileObservations(source: FileObservationSource): void {
+    this.disconnectFileObservations();
+    this.refreshObservation = source.refresh;
+    const receiveObservation = () => {
+      const observation = source.getObservation();
+      if (observation) this.receiveFileObservation(observation);
     };
-    this.unsubscribeVersionSource = source.subscribe(receiveVersion);
-    receiveVersion();
+    this.unsubscribeObservationSource = source.subscribe(receiveObservation);
+    receiveObservation();
   }
 
-  disconnectFileVersions(): void {
-    this.unsubscribeVersionSource?.();
-    this.unsubscribeVersionSource = null;
+  disconnectFileObservations(): void {
+    this.unsubscribeObservationSource?.();
+    this.unsubscribeObservationSource = null;
+    this.refreshObservation = null;
   }
 
   edit(content: string): void {
     if (this.disposed || content === this.snapshot.content) return;
+    this.reloadRequested = false;
     const modified = content !== this.persistedContent;
     let status: FileEditorStatus = modified ? "dirty" : "clean";
-    if (this.snapshot.status === "conflict" || this.snapshot.status === "loading") {
+    if (this.snapshot.status === "conflict") {
       status = "conflict";
     }
     this.setSnapshot({ ...this.snapshot, status, content, modified, error: null });
@@ -130,34 +144,32 @@ export class FileEditorModel {
     await this.performWrite(this.snapshot.observedVersion);
   }
 
-  receiveFileVersion(version: FileVersion): void {
-    if (this.disposed) return;
-    if (sameVersion(version, this.snapshot.observedVersion)) {
-      if (
-        version.status === "ready" &&
-        this.snapshot.observedVersion.status === "ready" &&
-        version.revision &&
-        !this.snapshot.observedVersion.revision
-      ) {
-        this.setSnapshot({
-          ...this.snapshot,
-          version:
-            this.snapshot.version.status === "ready"
-              ? { ...this.snapshot.version, revision: version.revision }
-              : this.snapshot.version,
-          observedVersion: version,
-        });
-      }
-      return;
-    }
-    if (this.restoreUnchangedConflict(version)) return;
+  receiveFileObservation(observation: FileEditorObservation): void {
+    if (this.disposed || observation === this.lastReceivedObservation) return;
+    this.lastReceivedObservation = observation;
+    const version = observationVersion(observation);
+    this.observed = observation;
     this.setSnapshot({ ...this.snapshot, observedVersion: version });
     if (this.snapshot.status === "saving") {
-      this.observedWhileSaving = version;
+      this.observedWhileSaving = observation;
       return;
     }
-    if (this.snapshot.status === "clean" || this.snapshot.status === "loading") {
-      void this.reloadFromDisk(version);
+    if (observation.status !== "ready") {
+      this.reloadRequested = false;
+      this.enterConflict(version);
+      return;
+    }
+    if (this.reloadRequested) {
+      this.reloadRequested = false;
+      this.applyFile(observation.file);
+      return;
+    }
+    if (observation.file.content === this.persistedContent) {
+      this.adoptUnchangedFile(observation.file);
+      return;
+    }
+    if (this.snapshot.status === "clean") {
+      this.applyFile(observation.file);
       return;
     }
     this.enterConflict(version);
@@ -171,14 +183,20 @@ export class FileEditorModel {
 
   async reload(): Promise<void> {
     if (this.disposed) return;
-    await this.reloadFromDisk(this.snapshot.observedVersion);
+    if (this.observed.status !== "ready") {
+      this.reloadRequested = true;
+      this.refreshObservation?.();
+      return;
+    }
+    this.applyFile(this.observed.file);
   }
 
   dispose(): void {
     this.disposed = true;
+    this.reloadRequested = false;
     this.saveSequence += 1;
     this.clearAutosave();
-    this.disconnectFileVersions();
+    this.disconnectFileObservations();
     this.listeners.clear();
   }
 
@@ -199,9 +217,10 @@ export class FileEditorModel {
     this.clearAutosave();
     const sequence = ++this.saveSequence;
     const content = this.snapshot.content;
+    const hasBom = this.hasBom;
     this.observedWhileSaving = null;
     this.setSnapshot({ ...this.snapshot, status: "saving", error: null });
-    const serializedContent = this.hasBom ? `\uFEFF${content}` : content;
+    const serializedContent = hasBom ? `\uFEFF${content}` : content;
     let result: FileWriteResult;
     try {
       result = await this.session.write({
@@ -224,11 +243,12 @@ export class FileEditorModel {
       return;
     }
     if (result.status === "conflict") {
+      this.observed = { status: "unsettled", version: result.version };
       this.enterConflict(result.version);
       return;
     }
 
-    const writtenVersion: FileVersion = {
+    const writtenVersion: Extract<FileVersion, { status: "ready" }> = {
       status: "ready",
       cwd: this.snapshot.version.cwd,
       path: this.snapshot.version.path,
@@ -236,64 +256,56 @@ export class FileEditorModel {
       modifiedAt: result.modifiedAt,
       revision: result.revision,
     };
-    const pending = this.observedWhileSaving;
-    this.observedWhileSaving = null;
+    const pending = this.takeObservedWhileSaving();
     this.persistedContent = content;
-    if (pending && !sameVersion(pending, writtenVersion)) {
+    if (pending && !observationMatchesWrite(pending, content, hasBom)) {
+      const pendingVersion = observationVersion(pending);
+      this.observed = pending;
       this.setSnapshot({
         ...this.snapshot,
         status: "conflict",
         modified: this.snapshot.content !== this.persistedContent,
         version: writtenVersion,
-        observedVersion: pending,
+        observedVersion: pendingVersion,
         error: null,
       });
       return;
     }
+    const settledVersion = pending?.status === "ready" ? pending.file.version : writtenVersion;
+    this.observed = pending ?? { status: "unsettled", version: writtenVersion };
     const modified = this.snapshot.content !== this.persistedContent;
     this.setSnapshot({
       ...this.snapshot,
       status: modified ? "dirty" : "clean",
       modified,
-      version: writtenVersion,
-      observedVersion: writtenVersion,
+      version: settledVersion,
+      observedVersion: settledVersion,
       error: null,
     });
     if (modified) this.scheduleAutosave();
   }
 
-  private async reloadFromDisk(version: FileVersion): Promise<void> {
+  private applyFile(file: FileEditorFile): void {
     this.clearAutosave();
-    if (version.status !== "ready") {
-      this.enterConflict(version);
-      return;
-    }
-    const sequence = ++this.saveSequence;
-    this.setSnapshot({ ...this.snapshot, status: "loading", error: null });
-    try {
-      const file = await this.session.read();
-      if (this.disposed || sequence !== this.saveSequence || this.snapshot.status !== "loading") {
-        return;
-      }
-      this.persistedContent = file.content;
-      this.hasBom = file.hasBom;
-      this.setSnapshot({
-        status: "clean",
-        content: file.content,
-        lineSeparator: detectLineSeparator(file.content),
-        modified: false,
-        version: file.version,
-        observedVersion: file.version,
-        error: null,
-      });
-    } catch (error) {
-      if (this.disposed || sequence !== this.saveSequence) return;
-      this.setSnapshot({
-        ...this.snapshot,
-        status: "error",
-        error: error instanceof Error ? error.message : String(error),
-      });
-    }
+    this.saveSequence += 1;
+    this.persistedContent = file.content;
+    this.hasBom = file.hasBom;
+    this.observed = { status: "ready", file };
+    this.setSnapshot({
+      status: "clean",
+      content: file.content,
+      lineSeparator: detectLineSeparator(file.content),
+      modified: false,
+      version: file.version,
+      observedVersion: file.version,
+      error: null,
+    });
+  }
+
+  private takeObservedWhileSaving(): FileEditorObservation | null {
+    const observation = this.observedWhileSaving;
+    this.observedWhileSaving = null;
+    return observation;
   }
 
   private enterConflict(version: FileVersion): void {
@@ -307,27 +319,23 @@ export class FileEditorModel {
     });
   }
 
-  private restoreUnchangedConflict(version: FileVersion): boolean {
-    if (
-      this.snapshot.status !== "conflict" ||
-      version.status !== "ready" ||
-      this.snapshot.version.status !== "ready" ||
-      !sameVersion(version, this.snapshot.version)
-    ) {
-      return false;
-    }
+  private adoptUnchangedFile(file: FileEditorFile): void {
+    this.hasBom = file.hasBom;
+    this.observed = { status: "ready", file };
     const modified = this.snapshot.content !== this.persistedContent;
+    const recovering = this.snapshot.status === "conflict";
+    let status = this.snapshot.status;
+    if (recovering) status = modified ? "dirty" : "clean";
     this.setSnapshot({
       ...this.snapshot,
-      status: modified ? "dirty" : "clean",
+      status,
       modified,
-      version,
-      observedVersion: version,
-      error: null,
+      version: file.version,
+      observedVersion: file.version,
+      error: recovering ? null : this.snapshot.error,
     });
-    if (modified) this.scheduleAutosave();
+    if (status === "dirty") this.scheduleAutosave();
     else this.clearAutosave();
-    return true;
   }
 
   private scheduleAutosave(): void {
@@ -377,13 +385,18 @@ function detectLineSeparator(content: string): FileLineSeparator {
   return "\n";
 }
 
-function sameVersion(left: FileVersion, right: FileVersion): boolean {
-  if (left.status !== right.status || left.cwd !== right.cwd || left.path !== right.path)
-    return false;
-  if (left.status === "ready" && right.status === "ready") {
-    if (left.revision && right.revision) return left.revision === right.revision;
-    return left.modifiedAt === right.modifiedAt && left.size === right.size;
-  }
-  if (left.status === "error" && right.status === "error") return left.error === right.error;
-  return true;
+function observationVersion(observation: FileEditorObservation): FileVersion {
+  return observation.status === "ready" ? observation.file.version : observation;
+}
+
+function observationMatchesWrite(
+  observation: FileEditorObservation,
+  content: string,
+  hasBom: boolean,
+): boolean {
+  return (
+    observation.status === "ready" &&
+    observation.file.content === content &&
+    observation.file.hasBom === hasBom
+  );
 }

packages/app/src/file-pane/editor/observation-source.test.ts

@@ -0,0 +1,60 @@
+import type { FileReadResult } from "@getpaseo/client/internal/daemon-client";
+import { describe, expect, test } from "vitest";
+import type { LiveFileObservation } from "../live-file/model";
+import { createFileObservationSource, type LiveObservationSource } from "./observation-source";
+
+class TestLiveObservationSource implements LiveObservationSource {
+  observation: LiveFileObservation | null;
+
+  constructor(observation: LiveFileObservation | null) {
+    this.observation = observation;
+  }
+
+  subscribe(): () => void {
+    return () => undefined;
+  }
+
+  getObservation(): LiveFileObservation | null {
+    return this.observation;
+  }
+
+  refresh(): void {}
+}
+
+function readyObservation(): LiveFileObservation {
+  const file: FileReadResult = {
+    bytes: new TextEncoder().encode("one"),
+    mime: "text/plain",
+    size: 3,
+    path: "file.ts",
+    kind: "text",
+    modifiedAt: "2026-07-18T00:00:00.000Z",
+    revision: "revision-1",
+  };
+  return {
+    status: "ready",
+    file,
+    version: {
+      status: "ready",
+      cwd: "/workspace",
+      path: "file.ts",
+      size: file.size,
+      modifiedAt: file.modifiedAt,
+      revision: file.revision,
+    },
+  };
+}
+
+describe("createFileObservationSource", () => {
+  test("returns the same editor observation until the live observation changes", () => {
+    const liveFile = new TestLiveObservationSource(readyObservation());
+    const source = createFileObservationSource(liveFile);
+
+    const first = source.getObservation();
+    const repeated = source.getObservation();
+
+    expect(repeated).toBe(first);
+    liveFile.observation = readyObservation();
+    expect(source.getObservation()).not.toBe(first);
+  });
+});

packages/app/src/file-pane/editor/observation-source.ts

@@ -0,0 +1,50 @@
+import { explorerFileFromReadResult } from "@/file-explorer/read-result";
+import type { LiveFileObservation } from "../live-file/model";
+import type { FileEditorObservation, FileObservationSource } from "./model";
+
+export interface LiveObservationSource {
+  subscribe(listener: () => void): () => void;
+  getObservation(): LiveFileObservation | null;
+  refresh(): void;
+}
+
+export function createFileObservationSource(
+  liveFile: LiveObservationSource,
+): FileObservationSource {
+  let liveObservation: LiveFileObservation | null = null;
+  let editorObservation: FileEditorObservation | null = null;
+  return {
+    subscribe: liveFile.subscribe,
+    refresh: liveFile.refresh,
+    getObservation() {
+      const nextLiveObservation = liveFile.getObservation();
+      if (nextLiveObservation === liveObservation) return editorObservation;
+      liveObservation = nextLiveObservation;
+      editorObservation = fileEditorObservation(nextLiveObservation);
+      return editorObservation;
+    },
+  };
+}
+
+function fileEditorObservation(
+  observation: LiveFileObservation | null,
+): FileEditorObservation | null {
+  if (!observation || observation.status !== "ready") return observation;
+  const decodedFile = explorerFileFromReadResult(observation.file);
+  if (decodedFile.kind !== "text" || decodedFile.content === undefined) {
+    return {
+      status: "error",
+      cwd: observation.version.cwd,
+      path: observation.version.path,
+      error: "File is no longer text.",
+    };
+  }
+  return {
+    status: "ready",
+    file: {
+      content: decodedFile.content,
+      hasBom: decodedFile.hasBom,
+      version: observation.version,
+    },
+  };
+}

packages/app/src/file-pane/live-file/hook.ts

@@ -38,7 +38,7 @@ export function useLiveFile(input: {
 
   const snapshot = useSyncExternalStore(model.subscribe, model.getSnapshot, model.getSnapshot);
   return {
-    file: snapshot.file,
+    file: snapshot.observation?.status === "ready" ? snapshot.observation.file : null,
     error: snapshot.read.status === "error" ? snapshot.read.error : null,
     isFetching: snapshot.read.status === "pending",
     isRetrying: snapshot.read.status === "pending" && snapshot.read.requested,

packages/app/src/file-pane/live-file/model.test.ts

@@ -117,6 +117,68 @@ async function waitForRead(
 }
 
 describe("LiveFileModel", () => {
+  it("does not publish a missing candidate when the following read succeeds", async () => {
+    const session = new TestLiveFileSession();
+    const model = new LiveFileModel();
+    model.open({
+      session,
+      target: { cwd: "/workspace", path: "file.ts" },
+      liveUpdates: true,
+    });
+    await waitForRead(session, 1);
+    session.reads[0].resolve(file());
+    await vi.waitFor(() => expect(model.getObservation()).toMatchObject({ status: "ready" }));
+    const publishedStatuses: string[] = [];
+    model.subscribe(() => {
+      const observation = model.getObservation();
+      if (observation) publishedStatuses.push(observation.status);
+    });
+
+    session.emit({ status: "missing", cwd: "/workspace", path: "file.ts" });
+    await waitForRead(session, 2);
+    session.reads[1].resolve(file());
+    await vi.waitFor(() => expect(model.getSnapshot().read).toEqual({ status: "idle" }));
+
+    expect(publishedStatuses).not.toContain("missing");
+  });
+
+  it("publishes missing when the following read also fails", async () => {
+    const session = new TestLiveFileSession();
+    const model = new LiveFileModel();
+    model.open({
+      session,
+      target: { cwd: "/workspace", path: "file.ts" },
+      liveUpdates: true,
+    });
+    await waitForRead(session, 1);
+    session.reads[0].resolve(file());
+    await vi.waitFor(() => expect(model.getObservation()?.status).toBe("ready"));
+
+    session.emit({ status: "missing", cwd: "/workspace", path: "file.ts" });
+    await waitForRead(session, 2);
+    session.reads[1].reject(new Error("File not found."));
+
+    await vi.waitFor(() => expect(model.getObservation()?.status).toBe("missing"));
+  });
+
+  it("preserves a missing candidate for its queued confirming read", async () => {
+    const session = new TestLiveFileSession();
+    const model = new LiveFileModel();
+    model.open({
+      session,
+      target: { cwd: "/workspace", path: "file.ts" },
+      liveUpdates: true,
+    });
+    await waitForRead(session, 1);
+
+    session.emit({ status: "missing", cwd: "/workspace", path: "file.ts" });
+    session.reads[0].resolve(file());
+    await waitForRead(session, 2);
+    session.reads[1].reject(new Error("File not found."));
+
+    await vi.waitFor(() => expect(model.getObservation()?.status).toBe("missing"));
+  });
+
   it("recovers only from a read begun after a missing observation", async () => {
     const session = new TestLiveFileSession();
     const model = new LiveFileModel();
@@ -127,7 +189,7 @@ describe("LiveFileModel", () => {
     });
     await waitForRead(session, 1);
     session.reads[0].resolve(file());
-    await vi.waitFor(() => expect(model.getSnapshot().file).toEqual(file()));
+    await vi.waitFor(() => expect(model.getObservation()).toMatchObject({ status: "ready" }));
 
     model.refresh();
     await waitForRead(session, 2);
@@ -135,14 +197,17 @@ describe("LiveFileModel", () => {
     session.reads[1].resolve(file("revision-2", "two"));
 
     await waitForRead(session, 3);
-    expect(model.getSnapshot().version?.status).toBe("missing");
+    expect(model.getObservation()?.status).toBe("ready");
     expect(model.getSnapshot().read).toEqual({ status: "pending", requested: true });
 
     session.reads[2].resolve(file("revision-2", "two"));
     await vi.waitFor(() => {
       expect(model.getSnapshot()).toMatchObject({
-        version: { status: "ready", revision: "revision-2" },
-        file: { revision: "revision-2" },
+        observation: {
+          status: "ready",
+          version: { revision: "revision-2" },
+          file: { revision: "revision-2" },
+        },
         read: { status: "idle" },
       });
     });
@@ -158,7 +223,7 @@ describe("LiveFileModel", () => {
     });
     await waitForRead(session, 1);
     session.reads[0].resolve(file());
-    await vi.waitFor(() => expect(model.getSnapshot().file).toEqual(file()));
+    await vi.waitFor(() => expect(model.getObservation()).toMatchObject({ status: "ready" }));
 
     session.emit({
       status: "error",
@@ -172,7 +237,7 @@ describe("LiveFileModel", () => {
 
     await vi.waitFor(() => {
       expect(model.getSnapshot()).toMatchObject({
-        version: { status: "error", error: "Requested path is not a file" },
+        observation: { status: "error", error: "Requested path is not a file" },
         read: { status: "error", error: "File unavailable." },
       });
     });
@@ -195,7 +260,7 @@ describe("LiveFileModel", () => {
     session.subscription.resolve({ initial: ready("revision-1"), unsubscribe() {} });
 
     await waitForRead(session, 1);
-    expect(model.getVersion()).toMatchObject({ status: "ready", revision: "revision-2" });
+    expect(model.getObservation()).toBeNull();
   });
 
   it("retries a failed subscription when the user refreshes", async () => {
@@ -210,7 +275,7 @@ describe("LiveFileModel", () => {
     expect(session.subscribeAttempts).toBe(1);
 
     session.reads[0].resolve(file());
-    await vi.waitFor(() => expect(model.getVersion()?.status).toBe("ready"));
+    await vi.waitFor(() => expect(model.getObservation()?.status).toBe("ready"));
     model.refresh();
 
     await waitForRead(session, 2);
@@ -247,8 +312,7 @@ describe("LiveFileModel", () => {
     await Promise.resolve();
 
     expect(model.getSnapshot()).toEqual({
-      file: null,
-      version: null,
+      observation: null,
       read: { status: "idle" },
     });
   });

packages/app/src/file-pane/live-file/model.ts

@@ -24,15 +24,21 @@ export type LiveFileReadState =
   | { status: "pending"; requested: boolean }
   | { status: "error"; error: string };
 
+export type LiveFileObservation =
+  | {
+      status: "ready";
+      version: Extract<FileVersion, { status: "ready" }>;
+      file: FileReadResult;
+    }
+  | Extract<FileVersion, { status: "missing" | "error" }>;
+
 export interface LiveFileSnapshot {
-  file: FileReadResult | null;
-  version: FileVersion | null;
+  observation: LiveFileObservation | null;
   read: LiveFileReadState;
 }
 
 const idleSnapshot: LiveFileSnapshot = {
-  file: null,
-  version: null,
+  observation: null,
   read: { status: "idle" },
 };
 
@@ -49,6 +55,7 @@ export class LiveFileModel {
   private activeReadSequence: number | null = null;
   private activeReadRequested = false;
   private observedAfterReadSequence: number | null = null;
+  private candidateVersion: FileVersion | null = null;
   private refreshQueued = false;
   private requestedRefreshQueued = false;
 
@@ -59,7 +66,7 @@ export class LiveFileModel {
 
   getSnapshot = (): LiveFileSnapshot => this.snapshot;
 
-  getVersion = (): FileVersion | null => this.snapshot.version;
+  getObservation = (): LiveFileObservation | null => this.snapshot.observation;
 
   open(input: { session: LiveFileSession; target: LiveFileTarget; liveUpdates: boolean }): void {
     this.reset();
@@ -111,6 +118,7 @@ export class LiveFileModel {
     this.activeReadSequence = null;
     this.activeReadRequested = false;
     this.observedAfterReadSequence = null;
+    this.candidateVersion = null;
     this.refreshQueued = false;
     this.requestedRefreshQueued = false;
     this.setSnapshot(idleSnapshot);
@@ -144,7 +152,7 @@ export class LiveFileModel {
 
   private observeVersion(version: FileVersion): void {
     this.observedAfterReadSequence = this.issuedReadSequence;
-    this.setSnapshot({ ...this.snapshot, version });
+    this.candidateVersion = version;
     this.scheduleRead(false);
   }
 
@@ -180,9 +188,13 @@ export class LiveFileModel {
       return;
     }
     this.observedAfterReadSequence = null;
+    this.candidateVersion = null;
     this.setSnapshot({
-      file: input.file,
-      version: readyVersion(input.target, input.file),
+      observation: {
+        status: "ready",
+        file: input.file,
+        version: readyVersion(input.target, input.file),
+      },
       read: { status: "idle" },
     });
     this.startQueuedRead();
@@ -203,11 +215,14 @@ export class LiveFileModel {
       return;
     }
     const message = errorMessage(input.error);
-    let version = this.snapshot.version;
-    if (version?.status !== "missing" && version?.status !== "error") {
-      version = { status: "error", cwd: input.target.cwd, path: input.target.path, error: message };
-    }
-    this.setSnapshot({ ...this.snapshot, version, read: { status: "error", error: message } });
+    const candidate = this.candidateVersion;
+    this.candidateVersion = null;
+    const candidateDescribesFailure =
+      candidate?.status === "missing" || candidate?.status === "error";
+    const observation: LiveFileObservation = candidateDescribesFailure
+      ? candidate
+      : { status: "error", cwd: input.target.cwd, path: input.target.path, error: message };
+    this.setSnapshot({ ...this.snapshot, observation, read: { status: "error", error: message } });
     this.startQueuedRead();
   }
 

packages/app/src/file-pane/pane.tsx

@@ -35,12 +35,8 @@ import { isWeb } from "@/constants/platform";
 import { useAppSettings } from "@/hooks/use-settings";
 import { useLiveFile } from "./live-file/hook";
 import { FilePanelBar } from "./bar";
-import {
-  FileEditorModel,
-  getFileConflictCallout,
-  type FileConflictCallout,
-  type FileEditorFile,
-} from "./editor/model";
+import { FileEditorModel, getFileConflictCallout, type FileConflictCallout } from "./editor/model";
+import { createFileObservationSource } from "./editor/observation-source";
 import { FileEditorView } from "./editor/view";
 import type { FileConflictAlertState } from "./conflict-alert";
 import type { LiveFileModel } from "./live-file/model";
@@ -667,25 +663,6 @@ function EditableFilePane({
   const [vimMode, setVimMode] = useState<string | null>(settings.vimKeybindings ? "NORMAL" : null);
   const session = useMemo(
     () => ({
-      async read(): Promise<FileEditorFile> {
-        const file = await client.readFile(cwd, path);
-        const decodedFile = explorerFileFromReadResult(file);
-        if (decodedFile.kind !== "text" || decodedFile.content === undefined) {
-          throw new Error("File is no longer text.");
-        }
-        return {
-          content: decodedFile.content,
-          hasBom: decodedFile.hasBom,
-          version: {
-            status: "ready",
-            cwd,
-            path,
-            size: file.size,
-            modifiedAt: file.modifiedAt,
-            revision: file.revision,
-          },
-        };
-      },
       write(input: { content: string; expectedModifiedAt: string; expectedRevision?: string }) {
         return client.writeFile({ cwd, path, ...input });
       },
@@ -703,14 +680,16 @@ function EditableFilePane({
           path,
           size: preview.size,
           modifiedAt: preview.modifiedAt,
+          revision: preview.revision,
         },
       },
       session,
     });
   });
   useEffect(() => {
-    model.connectFileVersions(liveFile);
-    return () => model.disconnectFileVersions();
+    const source = createFileObservationSource(liveFile);
+    model.connectFileObservations(source);
+    return () => model.disconnectFileObservations();
   }, [liveFile, model]);
   const snapshot = useSyncExternalStore(model.subscribe, model.getSnapshot, model.getSnapshot);
   const suspendPendingSave = useCallback(() => model.suspendAutosave(), [model]);

packages/app/src/stores/session-store.ts

@@ -272,6 +272,7 @@ export interface ExplorerFile {
   mimeType?: string;
   size: number;
   modifiedAt: string;
+  revision?: string;
 }
 
 export interface ExplorerDirectory {