Method getCodeGraph

src/mcp/tools.ts:1562–1638

* Get CodeGraph instance for a project * * If projectPath is provided, opens that project's CodeGraph (cached). * Otherwise returns the default CodeGraph instance. * * Walks up parent directories to find the nearest .codegraph/ folder, * similar to how git finds .git/ directories.

(projectPath?: string)

   * similar to how git finds .git/ directories.
   */
  private getCodeGraph(projectPath?: string): CodeGraph {
    if (!projectPath) {
      if (!this.cg) {
        const searched = this.defaultProjectHint ?? process.cwd();
        throw new NotIndexedError(
          'No CodeGraph project is loaded for this session.\n' +
          `Searched for a .codegraph/ directory starting from: ${searched}\n` +
          this.formatKnownSubprojects() +
          'Either the server root has no index of its own (e.g. a monorepo where only ' +
          "sub-projects are indexed), or the MCP client launched the server outside your " +
          'project without reporting the workspace root. Either way, target the project ' +
          'explicitly:\n' +
          '  • Pass projectPath to the tool call, e.g. projectPath: "/absolute/path/to/your/project" ' +
          '(any project that has a .codegraph/ — including a sub-project of a monorepo)\n' +
          '  • Or add --path to the server\'s MCP config args: ["serve", "--mcp", "--path", "/absolute/path/to/your/project"]\n' +
          'If a project simply has no index, use your built-in tools (Read/Grep/Glob) for THAT ' +
          "project (the user can run 'codegraph init' there to enable it) — you can still query " +
          'other indexed projects by projectPath in the same session.'
        );
      }
      return this.freshen(this.cg);
    }

    // Reject sensitive system directories before opening. Only validate a
    // path that actually exists — a nested or not-yet-created sub-path of a
    // real project must still be allowed to resolve UP to its .codegraph/
    // root below (issue #238), so we don't run the existence-checking
    // validator on paths that are meant to walk up.
    if (existsSync(projectPath)) {
      const pathError = validateProjectPath(projectPath);
      if (pathError) {
        throw new PathRefusalError(pathError);
      }
    }

    // Always RE-RESOLVE the nearest .codegraph/ from the input path. The walk
    // is cheap (a few existsSync up the tree) and is the only thing that
    // notices a path whose index root CHANGED since it was first seen — most
    // importantly a git worktree that gained its own .codegraph/ after the
    // (long-lived) server first resolved it up to the parent checkout. We used
    // to short-circuit on a `projectCache[projectPath]` entry before resolving,
    // which pinned that first resolution for the server's whole lifetime, so a
    // worktree kept being served the parent checkout's index until restart
    // (#926). The DB connection itself is still cached (by resolved root,
    // below), so re-resolving costs only the stat walk, never a reopen.
    const resolvedRoot = findNearestCodeGraphRoot(projectPath);

    if (!resolvedRoot) {
      throw new NotIndexedError(
        `The project at ${projectPath} isn't indexed with codegraph (no .codegraph/ directory found ` +
        'walking up from it), so codegraph cannot query it. Use your built-in tools (Read/Grep/Glob) ' +
        "for that codebase instead, and don't call codegraph for it again this session. " +
        "Indexing is the user's decision — they can run 'codegraph init' in that project to enable it."
      );
    }

    // If the path resolves to the default project, reuse the already-open
    // default instance rather than opening a SECOND connection to the same DB.