feat(25-06): merge git file service and history endpoint from worktree

Adds gitFileService with commitFile/getLog, wires git commits into
upload flow, adds GET /files/:fileId/history endpoint, and exports
ChatFileHistoryEntry type.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/shared/src/index.ts

@@ -623,6 +623,7 @@ export type {
   ChatFileReference,
   ChatFileUploadResponse,
   ChatFileListResponse,
+  ChatFileHistoryEntry,
   ChatPlaceholderEntry,
 } from "./types/chat.js";
 

packages/shared/src/types/chat.ts

@@ -118,6 +118,13 @@ export interface ChatBookmarkToggleResponse {
   bookmarked: boolean;
 }
 
+export interface ChatFileHistoryEntry {
+  hash: string;
+  date: string;
+  message: string;
+  author: string;
+}
+
 export interface ChatPlaceholderEntry {
   fileId: string;
   filename: string;

server/src/routes/chat-files.ts

@@ -9,6 +9,7 @@ import { chatService } from "../services/chat.js";
 import { isAllowedContentType, MAX_ATTACHMENT_BYTES } from "../attachment-types.js";
 import { assertBoard, assertCompanyAccess } from "./authz.js";
 import { placeholderService } from "../services/placeholder-service.js";
+import { gitFileService } from "../services/git-file-service.js";
 import { resolveDefaultStorageDir } from "../home-paths.js";
 
 const fileUpload = multer({
@@ -34,6 +35,7 @@ export function chatFileRoutes(db: Db, storage: StorageService) {
   const fileSvc = chatFileService(db);
   const convSvc = chatService(db);
   const phSvc = placeholderService();
+  const gitSvc = gitFileService();
   const storageDir = resolveDefaultStorageDir();
 
   // POST /conversations/:id/files — Upload a file to a conversation
@@ -100,6 +102,9 @@ export function chatFileRoutes(db: Db, storage: StorageService) {
       projectId: parsedMeta.data.projectId ?? null,
     });
 
+    // Git-track the uploaded file (non-blocking)
+    gitSvc.commitFile(storageDir, stored.objectKey, `Upload: ${file.originalname ?? "file"}`).catch(() => {});
+
     // Track placeholder if agent-generated and project-scoped
     if (parsedMeta.data.source === "agent_generated" && chatFile.projectId) {
       const projectDir = path.join(storageDir, "..", "..", "projects", chatFile.projectId);
@@ -128,6 +133,23 @@ export function chatFileRoutes(db: Db, storage: StorageService) {
     res.json({ items: files });
   });
 
+  // GET /files/:fileId/history — Git version history for a file
+  router.get("/files/:fileId/history", async (req, res) => {
+    assertBoard(req);
+
+    const fileId = req.params.fileId as string;
+    const chatFile = await fileSvc.getById(fileId);
+    if (!chatFile) {
+      res.status(404).json({ error: "File not found" });
+      return;
+    }
+    assertCompanyAccess(req, chatFile.companyId);
+
+    const limit = Math.min(parseInt(req.query.limit as string) || 50, 100);
+    const entries = await gitSvc.getLog(storageDir, chatFile.objectKey, limit);
+    res.json({ items: entries });
+  });
+
   // GET /files/:fileId/content — Serve file content (download/preview)
   router.get("/files/:fileId/content", async (req, res, next) => {
     assertBoard(req);

server/src/services/git-file-service.ts

@@ -0,0 +1,101 @@
+import { execFile as execFileCb } from "node:child_process";
+import { promisify } from "node:util";
+import { existsSync } from "node:fs";
+import path from "node:path";
+
+const execFile = promisify(execFileCb);
+
+export interface GitFileService {
+  ensureRepo(storageDir: string): Promise<void>;
+  commitFile(storageDir: string, objectKey: string, message: string): Promise<string | null>;
+  getLog(
+    storageDir: string,
+    objectKey: string,
+    limit?: number,
+  ): Promise<Array<{ hash: string; date: string; message: string; author: string }>>;
+}
+
+export function gitFileService(): GitFileService {
+  async function git(
+    cwd: string,
+    args: string[],
+  ): Promise<{ stdout: string; stderr: string }> {
+    return execFile("git", args, { cwd, timeout: 10000 });
+  }
+
+  return {
+    async ensureRepo(storageDir: string) {
+      const gitDir = path.join(storageDir, ".git");
+      if (existsSync(gitDir)) return;
+      await git(storageDir, ["init"]);
+      await git(storageDir, ["config", "user.email", "nexus@local"]);
+      await git(storageDir, ["config", "user.name", "Nexus File System"]);
+    },
+
+    async commitFile(
+      storageDir: string,
+      objectKey: string,
+      message: string,
+    ): Promise<string | null> {
+      const filePath = path.join(storageDir, objectKey);
+      if (!existsSync(filePath)) return null;
+
+      await this.ensureRepo(storageDir);
+
+      try {
+        await git(storageDir, ["add", "--", objectKey]);
+        const { stdout } = await git(storageDir, [
+          "commit",
+          "-m",
+          message,
+          "--",
+          objectKey,
+        ]);
+        const match = /\[[\w\s]+\s([a-f0-9]+)\]/.exec(stdout);
+        return match?.[1] ?? null;
+      } catch (err) {
+        const errMsg = String(
+          (err as { stderr?: string }).stderr ??
+            (err as Error).message ??
+            "",
+        );
+        if (
+          errMsg.includes("nothing to commit") ||
+          errMsg.includes("no changes added")
+        ) {
+          return null;
+        }
+        throw err;
+      }
+    },
+
+    async getLog(storageDir: string, objectKey: string, limit = 50) {
+      try {
+        await this.ensureRepo(storageDir);
+        const { stdout } = await git(storageDir, [
+          "log",
+          `--max-count=${limit}`,
+          "--format=%H|%aI|%s|%an",
+          "--",
+          objectKey,
+        ]);
+
+        return stdout
+          .trim()
+          .split("\n")
+          .filter(Boolean)
+          .map((line) => {
+            const [hash, date, message, author] = line.split("|");
+            return {
+              hash: hash!,
+              date: date!,
+              message: message!,
+              author: author!,
+            };
+          });
+      } catch {
+        return [];
+      }
+    },
+  };
+}