feat: Add Polymarket connector with Gamma API integration

[vale9888]

Team 18!

• Add Polymarket connector with 7 tools for prediction markets
• Implement Gamma API client with proper error handling
• Add comprehensive test suite following project standards
• Update TypeScript config to include DOM lib for fetch support
• Add detailed integration plan documentation
• Support both public data (no API key) and private data (with API key)
• Tools include: get markets, search markets, trending markets, user profile, positions, trade history

---

Summary by cubic

Add a Polymarket connector powered by the Gamma API, exposing 7 tools for prediction markets with solid error handling and full tests. Public data works without a key; user tools require an API key.

• New Features

  • Polymarket connector with 7 tools: get markets, get market, search, trending, user profile, positions, trade history.
  • Gamma API client with consistent errors and readable output formatting.
  • Comprehensive tests using MSW; detailed integration plan docs.
  • Connector exported in index; fetch enabled via DOM lib in tsconfig.

• Migration

  • No breaking changes.
  • Set the apiKey credential to use user-specific tools (profile, positions, trade history).

[cubic-dev-ai]

5 issues found across 5 files

_{React with 👍 or 👎 to teach cubic. You can also tag @cubic-dev-ai to give feedback, ask questions, or re-run the review.}

[cubic-dev-ai]

Including DOM in lib for a Node package is unnecessary with @types/node v22 and can pollute globals or cause subtle type conflicts; rely on Node’s fetch types instead.

(Based on your PR description about enabling fetch support by adding the DOM lib.)

Prompt for AI agents

Address the following comment on packages/mcp-connectors/tsconfig.json at line 3:

<comment>Including DOM in lib for a Node package is unnecessary with @types/node v22 and can pollute globals or cause subtle type conflicts; rely on Node’s fetch types instead.

(Based on your PR description about enabling fetch support by adding the DOM lib.)</comment>

<file context>
@@ -1,6 +1,6 @@
 {
     &quot;compilerOptions&quot;: {
-        &quot;lib&quot;: [&quot;ESNext&quot;],
+        &quot;lib&quot;: [&quot;ESNext&quot;, &quot;DOM&quot;],
         &quot;target&quot;: &quot;ESNext&quot;,
         &quot;module&quot;: &quot;ESNext&quot;,
</file context>

[cubic-dev-ai]

Hardcoded API key ('test-api-key') found in test file; secrets should not be committed to source control.

Prompt for AI agents

Address the following comment on packages/mcp-connectors/src/connectors/polymarket.spec.ts at line 126:

<comment>Hardcoded API key (&#39;test-api-key&#39;) found in test file; secrets should not be committed to source control.</comment>

<file context>
@@ -0,0 +1,406 @@
+        it(&#39;returns formatted markets list&#39;, async () =&gt; {
+          const tool = PolymarketConnectorConfig.tools.GET_MARKETS as MCPToolDefinition;
+          const mockContext = createMockConnectorContext({
+            apiKey: &#39;test-api-key&#39;,
+          });
+
</file context>

[cubic-dev-ai]

Zero value hidden by truthiness check; check for undefined/null instead so 0 is shown.

Prompt for AI agents

Address the following comment on packages/mcp-connectors/src/connectors/polymarket.ts at line 382:

<comment>Zero value hidden by truthiness check; check for undefined/null instead so 0 is shown.</comment>

<file context>
@@ -0,0 +1,431 @@
+   Outcome ID: ${pos.outcomeId}
+   Amount: ${pos.amount}
+   Average Price: $${pos.averagePrice}
+   ${pos.unrealizedPnL ? `Unrealized P&amp;L: $${pos.unrealizedPnL.toLocaleString()}` : &#39;&#39;}`
+          ).join(&#39;\n\n&#39;);
+          
</file context>

[cubic-dev-ai]

Zero value hidden by truthiness check; use an undefined/null check so 0 is displayed correctly.

Prompt for AI agents

Address the following comment on packages/mcp-connectors/src/connectors/polymarket.ts at line 352:

<comment>Zero value hidden by truthiness check; use an undefined/null check so 0 is displayed correctly.</comment>

<file context>
@@ -0,0 +1,431 @@
+          return `User Profile:
+Username: ${user.username || &#39;N/A&#39;}
+Balance: $${user.balance.toLocaleString()}
+${user.totalPnL ? `Total P&amp;L: $${user.totalPnL.toLocaleString()}` : &#39;&#39;}
+Active Positions: ${user.positions.length}`;
+        } catch (error) {
</file context>

[cubic-dev-ai]

Possible crash: reduce on potentially empty outcomes array; guard for empty outcomes before reducing or provide a safe fallback.

Prompt for AI agents

Address the following comment on packages/mcp-connectors/src/connectors/polymarket.ts at line 216:

<comment>Possible crash: reduce on potentially empty outcomes array; guard for empty outcomes before reducing or provide a safe fallback.</comment>

<file context>
@@ -0,0 +1,431 @@
+  }
+
+  const formatted = markets.map((market, index) =&gt; {
+    const topOutcome = market.outcomes.reduce((prev, current) =&gt; 
+      current.probability &gt; prev.probability ? current : prev
+    );
</file context>