fix: make run log creation atomic

src/main/database-base.ts

@@ -1,4 +1,4 @@
-import { mkdirSync } from "node:fs";
+import { mkdirSync, rmSync, writeFileSync } from "node:fs";
 import { join } from "node:path";
 import { DatabaseSync, type SQLInputValue } from "node:sqlite";
 import { buildThreadMethods } from "./database/threads";
@@ -38,6 +38,15 @@ function nowIso() {
   return new Date().toISOString();
 }
 
+function assertWritableDirectory(dir: string, label: string): void {
+  const probePath = join(dir, `.agentcompany-${label}-write-probe-${process.pid}-${Date.now()}`);
+  try {
+    writeFileSync(probePath, "", { encoding: "utf8", flag: "wx" });
+  } finally {
+    rmSync(probePath, { force: true });
+  }
+}
+
 export interface AppDatabaseCoreModules {
   threads: ReturnType<typeof buildThreadMethods>;
   company: ReturnType<typeof buildCompanyMethods>;
@@ -101,6 +110,7 @@ export class AppDatabaseBase {
     this.appVersion = options.appVersion ?? "unknown";
     mkdirSync(rootDir, { recursive: true });
     mkdirSync(this.logsDir, { recursive: true });
+    assertWritableDirectory(this.logsDir, "logs");
     mkdirSync(this.artifactsDir, { recursive: true });
     mkdirSync(this.backupsDir, { recursive: true });
     this.vault = new SecretVault(rootDir, { isPackaged: options.isPackaged });

src/main/database/runs.ts

@@ -1,5 +1,5 @@
 import { randomUUID } from "node:crypto";
-import { writeFileSync } from "node:fs";
+import { rmSync, writeFileSync } from "node:fs";
 import { join } from "node:path";
 import type { DatabaseSync, SQLInputValue } from "node:sqlite";
 import type { ConnectorId, RunRecord, RunUsageStatus } from "@shared/types";
@@ -24,6 +24,14 @@ export function buildRunMethods(
     logsDir: string;
   },
 ) {
+  function createEmptyRunLog(logPath: string): void {
+    writeFileSync(logPath, "", { encoding: "utf8", flag: "wx" });
+  }
+
+  function cleanupEmptyRunLog(logPath: string): void {
+    rmSync(logPath, { force: true });
+  }
+
   function insertRunRow(input: {
     id: string;
     companyId: string;
@@ -85,10 +93,15 @@ export function buildRunMethods(
       const id = input.id ?? randomUUID();
       const ts = nowIso();
       const logPath = join(deps.logsDir, `${id}.log`);
-      transaction(() => {
-        insertRunRow({ ...input, id, logPath, ts });
-      });
-      writeFileSync(logPath, "", "utf8");
+      createEmptyRunLog(logPath);
+      try {
+        transaction(() => {
+          insertRunRow({ ...input, id, logPath, ts });
+        });
+      } catch (error) {
+        cleanupEmptyRunLog(logPath);
+        throw error;
+      }
       return { id, logPath };
     },
 
@@ -103,6 +116,7 @@ export function buildRunMethods(
       const id = input.id ?? randomUUID();
       const ts = nowIso();
       const logPath = join(deps.logsDir, `${id}.log`);
+      createEmptyRunLog(logPath);
       try {
         transaction(() => {
           insertRunRow({ ...input, id, logPath, ts });
@@ -112,12 +126,12 @@ export function buildRunMethods(
           }
         });
       } catch (error) {
+        cleanupEmptyRunLog(logPath);
         if (error instanceof TaskCheckoutConflict) {
           return null;
         }
         throw error;
       }
-      writeFileSync(logPath, "", "utf8");
       return { id, logPath };
     },