feat: add repo evidence mcp tool

runners/agent-runner/src/ipc-repo-evidence-tool.ts

@@ -0,0 +1,53 @@
+import type { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
+import { z } from 'zod';
+
+import {
+  formatRepoEvidenceResponse,
+  REPO_EVIDENCE_ACTIONS,
+  runRepoEvidenceRequestDirect,
+} from './repo-evidence.js';
+
+export function registerRepoEvidenceTool(
+  server: McpServer,
+  repoRoot: string,
+): void {
+  server.tool(
+    'read_repo_evidence',
+    'Read fixed git evidence directly from EJCLAW_WORK_DIR without broad shell access. Use this when reviewer/arbiter needs current branch, dirty state, recent commits, or a specific commit/ref.',
+    {
+      action: z
+        .enum(REPO_EVIDENCE_ACTIONS)
+        .describe(
+          'git_status=current branch and dirty state, git_head=current HEAD, git_recent_log=recent commits, git_show_ref=show a specific ref/commit',
+        ),
+      ref: z
+        .string()
+        .optional()
+        .describe('Only for git_show_ref. Defaults to HEAD.'),
+      limit: z
+        .number()
+        .int()
+        .min(1)
+        .max(30)
+        .optional()
+        .describe('Only for git_recent_log. Defaults to 10, max 30.'),
+    },
+    async (args) => {
+      const response = await runRepoEvidenceRequestDirect(repoRoot, {
+        action: args.action,
+        ref: args.ref,
+        limit: args.limit,
+      });
+
+      return {
+        content: [
+          {
+            type: 'text' as const,
+            text: formatRepoEvidenceResponse(response),
+          },
+        ],
+        isError: !response.ok,
+      };
+    },
+  );
+}