diff --git a/.env.example b/.env.example
index 41f20ef..e1ffe93 100644
--- a/.env.example
+++ b/.env.example
@@ -13,6 +13,9 @@ export AGENT_URL=http://localhost:8123/   # AG-UI endpoint; the bundled Deep Age
 # export OPENAI_VERBOSITY=low
 
 # -- Internal Sources (Optional) --
+# A fine-grained PAT with read access enables GitHub code, repo, issue, and PR search.
+# export GITHUB_PERSONAL_ACCESS_TOKEN=github_pat_...
+# export GITHUB_MCP_URL=https://api.githubcopilot.com/mcp/readonly
 # Create a personal API key with PostHog's "MCP Server" preset.
 # The bundled connection uses CLI mode and is read-only.
 # export POSTHOG_PERSONAL_API_KEY=phx_...
diff --git a/.railway/railway.ts b/.railway/railway.ts
index 65f6b00..d79213e 100644
--- a/.railway/railway.ts
+++ b/.railway/railway.ts
@@ -26,6 +26,8 @@ export default defineRailway(() => {
       PORT: "8123",
       OPENAI_API_KEY: preserve(),
       TAVILY_API_KEY: preserve(),
+      GITHUB_PERSONAL_ACCESS_TOKEN: preserve(),
+      GITHUB_MCP_URL: preserve(),
       POSTHOG_PERSONAL_API_KEY: preserve(),
       POSTHOG_MCP_URL: preserve(),
       LINEAR_API_KEY: preserve(),
diff --git a/README.md b/README.md
index 0127074..6a6c395 100644
--- a/README.md
+++ b/README.md
@@ -27,6 +27,7 @@ runtime (Node + CopilotRuntime with embedded Channels)
 agent (Python + LangGraph deepagents)
           ├── OpenAI
           ├── Tavily (optional)
+          ├── GitHub MCP (optional, read-only)
           ├── PostHog MCP (optional, read-only)
           ├── Linear MCP (optional)
           └── Notion MCP (optional remote server)
@@ -67,8 +68,9 @@ Prerequisites: Node.js 22+, pnpm, Python 3.12, and
    INTELLIGENCE_API_KEY=cpk-...
    ```
 
-   Tavily, PostHog, Linear, and Notion are optional. Both Node and Python load
-   this root `.env`; Railway supplies the same values as service variables.
+   Tavily, GitHub, PostHog, Linear, and Notion are optional. Both Node and
+   Python load this root `.env`; Railway supplies the same values as service
+   variables.
 
    `INTELLIGENCE_API_URL` and `INTELLIGENCE_GATEWAY_WS_URL` default to the
    production Intelligence endpoints. `INTELLIGENCE_CHANNEL_NAME` defaults to
@@ -140,6 +142,9 @@ Slack app**. Reusing it preserves the bot user, workspace installation, and
 
 - `TAVILY_API_KEY` enables live web research. Without it, OpenTag still chats,
   triages requests and renders UI from model knowledge.
+- `GITHUB_PERSONAL_ACCESS_TOKEN` enables read-only repository, code, issue, and
+  pull-request search through GitHub's hosted MCP. `GITHUB_MCP_URL` can override
+  the endpoint; OpenTag still sends GitHub's read-only configuration header.
 - `POSTHOG_PERSONAL_API_KEY` enables PostHog analytics through its hosted MCP.
   Create the key with PostHog's **MCP Server** preset. The default connection is
   token-efficient and read-only; `POSTHOG_MCP_URL` can override the endpoint.
@@ -165,8 +170,9 @@ The runtime reaches the agent over Railway private networking and embeds the
 managed `open-tag` Channel. Railway sets
 `INTELLIGENCE_CHANNEL_NAME=open-tag`; Intelligence owns both platform
 adapters. The runtime API key is preserved. OpenAI is required on `agent`;
-Tavily, PostHog, Linear, and remote Notion settings are optional. Connecting both
-services to `main` enables GitHub-triggered deployments after merges.
+Tavily, GitHub search, PostHog, Linear, and remote Notion settings are optional.
+Connecting both services to `main` enables GitHub-triggered deployments after
+merges.
 
 The repository configuration does not mutate the existing production Railway
 project. Inventory and cutover should happen after Railway authentication.
diff --git a/agent/internal_sources.py b/agent/internal_sources.py
index f9a5383..1471b3f 100644
--- a/agent/internal_sources.py
+++ b/agent/internal_sources.py
@@ -1,4 +1,4 @@
-"""Optional PostHog, Linear, and Notion MCP integrations."""
+"""Optional GitHub, PostHog, Linear, and Notion MCP integrations."""
 
 import asyncio
 import logging
@@ -13,6 +13,15 @@
 
 
 MCP_SERVERS = {
+    "github": {
+        "token_env": "GITHUB_PERSONAL_ACCESS_TOKEN",
+        "url_env": "GITHUB_MCP_URL",
+        "default_url": "https://api.githubcopilot.com/mcp/readonly",
+        "headers": {
+            "X-MCP-Readonly": "true",
+            "X-MCP-Toolsets": "repos,issues,pull_requests",
+        },
+    },
     "posthog": {
         "token_env": "POSTHOG_PERSONAL_API_KEY",
         "url_env": "POSTHOG_MCP_URL",
@@ -82,10 +91,14 @@ def _configured_connections(
             )
             continue
 
+        headers = {
+            "Authorization": f"Bearer {token}",
+            **config.get("headers", {}),
+        }
         connections[name] = {
             "transport": "streamable_http",
             "url": url,
-            "headers": {"Authorization": f"Bearer {token}"},
+            "headers": headers,
         }
     return connections
 
diff --git a/agent/prompts/system.py b/agent/prompts/system.py
index 1616c24..b83641e 100644
--- a/agent/prompts/system.py
+++ b/agent/prompts/system.py
@@ -1,7 +1,7 @@
 """Core OpenTag persona and workflow."""
 
 SYSTEM_PROMPT = """You are OpenTag, your team's on-call triage assistant for fast
-incident support, research, and Linear/Notion workflows.
+incident support, research, GitHub search, and Linear/Notion workflows.
 
 Hard rules (ALWAYS follow):
 - NEVER output raw JSON, data structures, or code blocks in your messages
diff --git a/agent/prompts/tools.py b/agent/prompts/tools.py
index f348fca..24fd15f 100644
--- a/agent/prompts/tools.py
+++ b/agent/prompts/tools.py
@@ -1,7 +1,9 @@
 """Guidance for internal sources and write tools."""
 
 TOOLS_PROMPT = """- For internal or company-specific questions, prefer the team's Notion/Linear
-  (internal sources) first; use the web for external questions
+  and GitHub sources first; use the web for external questions
+- Use GitHub tools to search repositories, code, issues, and pull requests. The
+  GitHub integration is read-only
 - CRITICAL: Every Linear or Notion mutation tool automatically pauses with its
   exact action and draft details. Call the mutation once; it runs only after
   the user grants approval, and otherwise no write occurs
diff --git a/agent/tests/test_agent_configuration.py b/agent/tests/test_agent_configuration.py
index 1a01ab7..94c2eee 100644
--- a/agent/tests/test_agent_configuration.py
+++ b/agent/tests/test_agent_configuration.py
@@ -39,6 +39,7 @@ def build_with_captured_configuration(monkeypatch):
 
     monkeypatch.setenv("OPENAI_API_KEY", "sk-test")
     monkeypatch.delenv("TAVILY_API_KEY", raising=False)
+    monkeypatch.delenv("GITHUB_PERSONAL_ACCESS_TOKEN", raising=False)
     monkeypatch.delenv("POSTHOG_PERSONAL_API_KEY", raising=False)
     monkeypatch.delenv("LINEAR_API_KEY", raising=False)
     monkeypatch.delenv("NOTION_MCP_AUTH_TOKEN", raising=False)
@@ -146,6 +147,7 @@ def _generate(
     model = RecordingOpenAIModel()
     monkeypatch.setenv("OPENAI_API_KEY", "sk-test")
     monkeypatch.delenv("TAVILY_API_KEY", raising=False)
+    monkeypatch.delenv("GITHUB_PERSONAL_ACCESS_TOKEN", raising=False)
     monkeypatch.delenv("POSTHOG_PERSONAL_API_KEY", raising=False)
     monkeypatch.delenv("LINEAR_API_KEY", raising=False)
     monkeypatch.delenv("NOTION_MCP_AUTH_TOKEN", raising=False)
@@ -170,6 +172,7 @@ def _configure_minimal_environment(monkeypatch):
     monkeypatch.delenv("OPENAI_REASONING_EFFORT", raising=False)
     monkeypatch.delenv("OPENAI_VERBOSITY", raising=False)
     monkeypatch.delenv("TAVILY_API_KEY", raising=False)
+    monkeypatch.delenv("GITHUB_PERSONAL_ACCESS_TOKEN", raising=False)
     monkeypatch.delenv("POSTHOG_PERSONAL_API_KEY", raising=False)
     monkeypatch.delenv("LINEAR_API_KEY", raising=False)
     monkeypatch.delenv("NOTION_MCP_AUTH_TOKEN", raising=False)
diff --git a/agent/tests/test_health.py b/agent/tests/test_health.py
index 8529298..cb39210 100644
--- a/agent/tests/test_health.py
+++ b/agent/tests/test_health.py
@@ -7,6 +7,7 @@
 def test_health_ok(monkeypatch):
     monkeypatch.setenv("OPENAI_API_KEY", "sk-test")
     monkeypatch.delenv("TAVILY_API_KEY", raising=False)
+    monkeypatch.delenv("GITHUB_PERSONAL_ACCESS_TOKEN", raising=False)
     monkeypatch.delenv("POSTHOG_PERSONAL_API_KEY", raising=False)
     monkeypatch.delenv("LINEAR_API_KEY", raising=False)
     monkeypatch.delenv("NOTION_MCP_AUTH_TOKEN", raising=False)
@@ -24,6 +25,7 @@ def test_health_ok(monkeypatch):
 def test_server_exposes_opentag_metadata(monkeypatch):
     monkeypatch.setenv("OPENAI_API_KEY", "sk-test")
     monkeypatch.delenv("TAVILY_API_KEY", raising=False)
+    monkeypatch.delenv("GITHUB_PERSONAL_ACCESS_TOKEN", raising=False)
     monkeypatch.delenv("POSTHOG_PERSONAL_API_KEY", raising=False)
     monkeypatch.delenv("LINEAR_API_KEY", raising=False)
     monkeypatch.delenv("NOTION_MCP_AUTH_TOKEN", raising=False)
@@ -52,6 +54,7 @@ def test_local_agent_port_rejects_invalid_server_port():
 def test_build_agent_without_tavily(monkeypatch, capsys):
     monkeypatch.setenv("OPENAI_API_KEY", "sk-test")
     monkeypatch.delenv("TAVILY_API_KEY", raising=False)
+    monkeypatch.delenv("GITHUB_PERSONAL_ACCESS_TOKEN", raising=False)
     monkeypatch.delenv("POSTHOG_PERSONAL_API_KEY", raising=False)
     monkeypatch.delenv("LINEAR_API_KEY", raising=False)
     monkeypatch.delenv("NOTION_MCP_AUTH_TOKEN", raising=False)
@@ -64,6 +67,7 @@ def test_build_agent_without_tavily(monkeypatch, capsys):
 def test_build_agent_with_tavily(monkeypatch, capsys):
     monkeypatch.setenv("OPENAI_API_KEY", "sk-test")
     monkeypatch.setenv("TAVILY_API_KEY", "tvly-test")
+    monkeypatch.delenv("GITHUB_PERSONAL_ACCESS_TOKEN", raising=False)
     monkeypatch.delenv("POSTHOG_PERSONAL_API_KEY", raising=False)
     monkeypatch.delenv("LINEAR_API_KEY", raising=False)
     monkeypatch.delenv("NOTION_MCP_AUTH_TOKEN", raising=False)
diff --git a/agent/tests/test_internal_sources.py b/agent/tests/test_internal_sources.py
index 6979507..debfad8 100644
--- a/agent/tests/test_internal_sources.py
+++ b/agent/tests/test_internal_sources.py
@@ -9,12 +9,22 @@
 
 
 @pytest.fixture(autouse=True)
-def clear_posthog_credentials(monkeypatch):
+def clear_ambient_credentials(monkeypatch):
+    monkeypatch.delenv("GITHUB_PERSONAL_ACCESS_TOKEN", raising=False)
     monkeypatch.delenv("POSTHOG_PERSONAL_API_KEY", raising=False)
 
 
 def test_mcp_servers_are_configured_in_one_place():
     assert internal_sources.MCP_SERVERS == {
+        "github": {
+            "token_env": "GITHUB_PERSONAL_ACCESS_TOKEN",
+            "url_env": "GITHUB_MCP_URL",
+            "default_url": "https://api.githubcopilot.com/mcp/readonly",
+            "headers": {
+                "X-MCP-Readonly": "true",
+                "X-MCP-Toolsets": "repos,issues,pull_requests",
+            },
+        },
         "posthog": {
             "token_env": "POSTHOG_PERSONAL_API_KEY",
             "url_env": "POSTHOG_MCP_URL",
@@ -36,12 +46,46 @@ def test_mcp_servers_are_configured_in_one_place():
 
 
 def test_internal_source_tools_empty_without_env(monkeypatch):
+    monkeypatch.delenv("GITHUB_PERSONAL_ACCESS_TOKEN", raising=False)
     monkeypatch.delenv("POSTHOG_PERSONAL_API_KEY", raising=False)
     monkeypatch.delenv("LINEAR_API_KEY", raising=False)
     monkeypatch.delenv("NOTION_MCP_AUTH_TOKEN", raising=False)
     assert internal_sources.internal_source_tools() == []
 
 
+def test_github_uses_hosted_read_only_search_mcp_with_pat():
+    assert internal_sources._configured_connections(
+        {"GITHUB_PERSONAL_ACCESS_TOKEN": "github_pat_test"}
+    ) == {
+        "github": {
+            "transport": "streamable_http",
+            "url": "https://api.githubcopilot.com/mcp/readonly",
+            "headers": {
+                "Authorization": "Bearer github_pat_test",
+                "X-MCP-Readonly": "true",
+                "X-MCP-Toolsets": "repos,issues,pull_requests",
+            },
+        }
+    }
+
+
+def test_github_url_can_be_overridden_without_disabling_read_only_mode():
+    assert internal_sources._configured_connections(
+        {
+            "GITHUB_PERSONAL_ACCESS_TOKEN": "github_pat_test",
+            "GITHUB_MCP_URL": "https://github.example.test/mcp",
+        }
+    )["github"] == {
+        "transport": "streamable_http",
+        "url": "https://github.example.test/mcp",
+        "headers": {
+            "Authorization": "Bearer github_pat_test",
+            "X-MCP-Readonly": "true",
+            "X-MCP-Toolsets": "repos,issues,pull_requests",
+        },
+    }
+
+
 def test_posthog_uses_hosted_read_only_mcp_with_personal_api_key():
     assert internal_sources._configured_connections(
         {"POSTHOG_PERSONAL_API_KEY": "phx_test"}
diff --git a/agent/tests/test_prompts.py b/agent/tests/test_prompts.py
index e6cb007..d53d4b4 100644
--- a/agent/tests/test_prompts.py
+++ b/agent/tests/test_prompts.py
@@ -19,6 +19,11 @@ def test_prompt_uses_triage_first_behavior():
     assert "/reports/final_report.md" not in BASE_SYSTEM_PROMPT
 
 
+def test_prompt_describes_read_only_github_search():
+    assert "GitHub tools to search repositories" in BASE_SYSTEM_PROMPT
+    assert "GitHub integration is read-only" in BASE_SYSTEM_PROMPT
+
+
 def test_prompt_describes_direct_optional_web_search():
     assert "web_search(query, max_results=5)" in WEB_SEARCH_TOOL_ADDENDUM
     assert "source snippets" in WEB_SEARCH_TOOL_ADDENDUM
diff --git a/app/railway.test.ts b/app/railway.test.ts
index 8f836b3..650929d 100644
--- a/app/railway.test.ts
+++ b/app/railway.test.ts
@@ -68,6 +68,8 @@ describe("Railway deployment graph", () => {
     expect(agent?.variables).toMatchObject({
       OPENAI_API_KEY: { type: "preserve" },
       TAVILY_API_KEY: { type: "preserve" },
+      GITHUB_PERSONAL_ACCESS_TOKEN: { type: "preserve" },
+      GITHUB_MCP_URL: { type: "preserve" },
       POSTHOG_PERSONAL_API_KEY: { type: "preserve" },
       POSTHOG_MCP_URL: { type: "preserve" },
       LINEAR_API_KEY: { type: "preserve" },
diff --git a/setup.md b/setup.md
index e62f4dd..742881f 100644
--- a/setup.md
+++ b/setup.md
@@ -61,6 +61,8 @@ cp .env.example .env
 | `OPENAI_REASONING_EFFORT` | No | Defaults to `low` |
 | `OPENAI_VERBOSITY` | No | Defaults to `low` |
 | `TAVILY_API_KEY` | No | Enables live web research |
+| `GITHUB_PERSONAL_ACCESS_TOKEN` | No | Enables read-only GitHub repository, code, issue, and PR search |
+| `GITHUB_MCP_URL` | No | Overrides the hosted GitHub MCP URL; OpenTag still sends read-only headers |
 | `POSTHOG_PERSONAL_API_KEY` | No | Enables the hosted PostHog MCP in read-only CLI mode |
 | `POSTHOG_MCP_URL` | No | Overrides the hosted PostHog MCP URL |
 | `LINEAR_API_KEY` | No | Enables the hosted Linear MCP |
@@ -179,6 +181,15 @@ Reads and UI rendering are never gated.
 Set `TAVILY_API_KEY` in the root `.env` to enable live web research. The
 `web_search` tool is not registered when the key is absent.
 
+### GitHub
+
+Set `GITHUB_PERSONAL_ACCESS_TOKEN` in the root `.env` to enable GitHub search.
+Use a fine-grained personal access token limited to the repositories and read
+permissions the agent needs. OpenTag connects to GitHub's hosted MCP with only
+the repository, issue, and pull-request toolsets and requests read-only mode.
+Set `GITHUB_MCP_URL` only to override the hosted endpoint, then restart
+`pnpm agent` so it discovers the tools.
+
 ### PostHog
 
 Create a PostHog personal API key using the **MCP Server** preset, then set
@@ -212,8 +223,8 @@ The IaC file declares exactly:
 `runtime.AGENT_URL` references the agent's Railway private domain and port.
 Production Intelligence URLs are literal configuration, the API key is
 preserved, and the Channel name is `open-tag`. `OPENAI_API_KEY` is required on
-`agent`; Tavily, PostHog, Linear, and the paired remote Notion variables are
-optional preserved settings.
+`agent`; Tavily, GitHub, PostHog, Linear, and the paired remote Notion variables
+are optional preserved settings.
 
 Evaluate the configuration locally without applying it: