feat: Add codegraph (#22485)

.claude/CLAUDE.md

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+<!-- CODEGRAPH_START -->
+## CodeGraph
+
+In repositories indexed by CodeGraph (a `.codegraph/` directory exists at the repo root), reach for it BEFORE grep/find or reading files when you need to understand or locate code:
+
+- **MCP tool** (when available): `codegraph_explore` answers most code questions in one call — the relevant symbols' verbatim source plus the call paths between them, including dynamic-dispatch hops grep can't follow. Name a file or symbol in the query to read its current line-numbered source. If it's listed but deferred, load it by name via tool search.
+- **Shell** (always works): `codegraph explore "<symbol names or question>"` prints the same output.
+
+If there is no `.codegraph/` directory, skip CodeGraph entirely — indexing is the user's decision.
+<!-- CODEGRAPH_END -->

.claude/settings.json

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+{
+  "permissions": {
+    "allow": [
+      "mcp__codegraph__*"
+    ]
+  },
+  "hooks": {
+    "UserPromptSubmit": [
+      {
+        "hooks": [
+          {
+            "type": "command",
+            "command": "codegraph prompt-hook"
+          }
+        ]
+      }
+    ]
+  }
+}

.codegraph/.gitignore

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+# CodeGraph data files — local to each machine, not for committing.
+# Ignore everything in .codegraph/ except this file itself, so transient
+# files (the database, daemon.pid, sockets, logs) never show up in git.
+*
+!.gitignore

.cursor/mcp.json

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+{
+  "mcpServers": {
+    "codegraph": {
+      "type": "stdio",
+      "command": "codegraph",
+      "args": [
+        "serve",
+        "--mcp",
+        "--path",
+        "."
+      ]
+    }
+  }
+}

.mcp.json

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+{
+  "mcpServers": {
+    "codegraph": {
+      "type": "stdio",
+      "command": "codegraph",
+      "args": [
+        "serve",
+        "--mcp"
+      ]
+    }
+  }
+}