diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8ed8ef1584..84e34931b9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -22,6 +22,7 @@ _In development — bullets added per PR; finalized at release._
 - **fix(translator):** strip Claude output_config before MiniMax (rejected upstream). (thanks @hiepau1231)
 - **fix(combo): round-robin members fail over faster under concurrency saturation via a configurable queue depth** — when a round-robin combo member was saturated, requests sat in the per-model semaphore's **unbounded** queue and only failed over to the next member after the full `queueTimeoutMs` (default 30s) elapsed — so a burst of agentic requests deep-queued one hot member instead of spilling to healthy ones. The per-model semaphore now accepts a bounded queue depth and emits `SEMAPHORE_QUEUE_FULL` once it is full (the round-robin loop already cascades on that code), so a configured low depth fails over immediately. A new `queueDepth` combo-config knob (global default / provider override / per-combo, default **20** for backward compatibility; **0** = never queue → fail over now) is exposed in Settings → Combo Defaults. ([#3872](https://github.com/diegosouzapw/OmniRoute/issues/3872) — thanks @KooshaPari)
 - **fix(pricing): align Claude Code (`cc`) pricing with current Anthropic per-MTok rates** — the `cc` provider block in the default pricing table had stale numbers across every Claude 4.x family entry — most visibly, `claude-opus-4-5-20251101` was billed at the deprecated Opus 4.1 rate (`input $15` / `output $75`), and `claude-haiku-4-5-20251001` was at half the current Haiku 4.5 rate. The `cached` (cache hit) and `cache_creation` (5-minute cache write) multipliers were also off across Opus 4.6/4.7/4.8, Sonnet 4.5/4.6, Haiku 4.5, and Fable 5. All eight entries now match the rates Anthropic publishes (input, 5m cache write at 1.25x input, cache hit at 0.1x input, output; reasoning billed at the output rate), so cost accounting on the dashboard and per-request usage events stop under- or over-reporting Claude Code spend. (thanks @chulanpro5)
+- **fix(executors): sanitize Anthropic-shape content parts before GitHub Copilot `/chat/completions`** — Claude models on GitHub Copilot driven from clients like Cursor IDE (e.g. `gh/claude-sonnet-4.6`) failed with `Provider returned error: type has to be either 'image_url' or 'text' (reset after 30s)` because the client passed through Anthropic-shape content parts (`tool_use`, `tool_result`, `thinking`) untouched, and the Copilot chat-completions endpoint only accepts `text`/`image_url`. `GithubExecutor.transformRequest` now serializes any unsupported part type as `text` (preserving the model's context), drops empty parts, and collapses to `null` when an assistant message's only content was tool_calls — `tool_calls` ride alongside untouched. Codex-family models still route through `/responses` unchanged. (thanks @cngznNN)
 
 ---
 
diff --git a/open-sse/executors/github.ts b/open-sse/executors/github.ts
index 98a965f17e..6fcdd2e18c 100644
--- a/open-sse/executors/github.ts
+++ b/open-sse/executors/github.ts
@@ -99,9 +99,51 @@ export class GithubExecutor extends BaseExecutor {
       modifiedBody.tools = modifiedBody.tools.slice(0, 128);
     }
 
+    // GitHub Copilot /chat/completions only accepts {type:'text'} or {type:'image_url'}
+    // content parts. Clients like Cursor IDE pass through Anthropic-shape parts
+    // (tool_use, tool_result, thinking) untouched when using Claude models, which makes
+    // the endpoint return: "type has to be either 'image_url' or 'text'" (HTTP 400).
+    // Serialize unknown part types as text, drop empty parts, and collapse to null when
+    // every part is stripped (assistant messages whose only content was tool_calls).
+    // Port from 9router#220 (fixes 9router#219).
+    if (Array.isArray(modifiedBody.messages)) {
+      modifiedBody.messages = modifiedBody.messages.map((msg: any) =>
+        this.sanitizeChatCompletionsMessage(msg)
+      );
+    }
+
     return modifiedBody;
   }
 
+  private sanitizeChatCompletionsMessage(msg: any): any {
+    if (!msg || typeof msg !== "object") return msg;
+    // String content and missing content (e.g. assistant w/ only tool_calls) pass through.
+    if (typeof msg.content === "string" || msg.content == null) return msg;
+    if (!Array.isArray(msg.content)) return msg;
+
+    const cleanContent = msg.content
+      .map((part: any) => {
+        if (!part || typeof part !== "object") return part;
+        if (part.type === "text") return part;
+        if (part.type === "image_url") return part;
+        // Serialize any unsupported part (tool_use, tool_result, thinking, etc.) as text.
+        // Try common text-carrying fields first; fall back to a JSON dump so nothing is
+        // silently dropped from the model's context.
+        const raw =
+          (typeof part.text === "string" && part.text) ||
+          (typeof part.thinking === "string" && part.thinking) ||
+          (typeof part.content === "string" && part.content) ||
+          (part.content != null && JSON.stringify(part.content)) ||
+          JSON.stringify(part);
+        return { type: "text", text: typeof raw === "string" ? raw : JSON.stringify(raw) };
+      })
+      .filter((part: any) => !(part && part.type === "text" && part.text === ""));
+
+    // If every part stripped to empty (e.g. tool_use with no text), collapse to null so
+    // GitHub does not reject an empty-array body. tool_calls ride alongside content.
+    return { ...msg, content: cleanContent.length > 0 ? cleanContent : null };
+  }
+
   async execute(input: ExecuteInput) {
     const result = await super.execute(input);
     if (!result || !result.response) return result;
diff --git a/tests/unit/executor-github.test.ts b/tests/unit/executor-github.test.ts
index 95cf3bcc2f..dd2c1a4b3c 100644
--- a/tests/unit/executor-github.test.ts
+++ b/tests/unit/executor-github.test.ts
@@ -97,6 +97,102 @@ test("GithubExecutor.transformRequest injects JSON response instructions for Cla
   assert.equal(result.messages[2].reasoning_content, undefined);
 });
 
+test("GithubExecutor.transformRequest sanitizes Anthropic-shape content parts (tool_use, tool_result, thinking) for /chat/completions (port from 9router#220)", () => {
+  // GitHub Copilot /chat/completions only accepts {type:'text'} or {type:'image_url'} content
+  // parts. Clients like Cursor IDE pass through Anthropic-shape parts (tool_use, tool_result,
+  // thinking) untouched when using Claude models, which makes the endpoint return:
+  //   "type has to be either 'image_url' or 'text'" (HTTP 400)
+  // Port: serialize unknown part types as text, drop empty content, and skip assistant
+  // messages whose only content was tool_calls (content collapses to null).
+  const executor = new GithubExecutor();
+  const body = {
+    messages: [
+      {
+        role: "user",
+        content: [
+          { type: "text", text: "Search for X" },
+          { type: "image_url", image_url: { url: "data:image/png;base64,AAAA" } },
+        ],
+      },
+      {
+        role: "assistant",
+        content: [
+          { type: "thinking", thinking: "let me search" },
+          { type: "tool_use", id: "call_1", name: "search", input: { q: "X" } },
+        ],
+      },
+      {
+        role: "tool",
+        tool_call_id: "call_1",
+        content: [{ type: "tool_result", tool_use_id: "call_1", content: "result" }],
+      },
+    ],
+  };
+
+  const result = executor.transformRequest("claude-sonnet-4.6", body, true, {});
+
+  // user message keeps text + image_url parts untouched
+  assert.equal(result.messages[0].content[0].type, "text");
+  assert.equal(result.messages[0].content[0].text, "Search for X");
+  assert.equal(result.messages[0].content[1].type, "image_url");
+  assert.equal(result.messages[0].content[1].image_url?.url, "data:image/png;base64,AAAA");
+
+  // assistant: thinking + tool_use serialized to text type — no unknown type leaks to wire
+  for (const part of result.messages[1].content) {
+    assert.ok(part.type === "text" || part.type === "image_url", `unsupported type leaked: ${part.type}`);
+  }
+  assert.ok(result.messages[1].content.some((p: any) => /let me search/.test(p.text)));
+  assert.ok(result.messages[1].content.some((p: any) => /search/.test(p.text) && /"q":"X"/.test(p.text)));
+
+  // tool message: tool_result serialized to text — no unknown type leaks
+  for (const part of result.messages[2].content) {
+    assert.ok(part.type === "text" || part.type === "image_url", `unsupported type leaked: ${part.type}`);
+  }
+});
+
+test("GithubExecutor.transformRequest collapses assistant content to null when every part stripped to empty", () => {
+  // assistant messages whose only content was tool_use (no text) should not ship empty
+  // strings to /chat/completions — GitHub rejects "" parts. Mirror upstream by dropping
+  // empty parts and falling back to null when nothing meaningful remains.
+  const executor = new GithubExecutor();
+  const body = {
+    messages: [
+      {
+        role: "assistant",
+        content: [{ type: "tool_use", id: "call_x", name: "noop", input: {} }],
+        tool_calls: [{ id: "call_x", type: "function", function: { name: "noop", arguments: "{}" } }],
+      },
+    ],
+  };
+
+  const result = executor.transformRequest("claude-sonnet-4.6", body, true, {});
+  // Either null or an array of {text:non-empty} — never an empty-text part.
+  const c = result.messages[0].content;
+  if (Array.isArray(c)) {
+    for (const part of c) {
+      assert.notEqual(part.text, "", "empty text part leaked to wire");
+    }
+  } else {
+    assert.equal(c, null);
+  }
+  // tool_calls must survive — they ride alongside content
+  assert.equal(result.messages[0].tool_calls[0].id, "call_x");
+});
+
+test("GithubExecutor.transformRequest leaves string content and missing content untouched", () => {
+  const executor = new GithubExecutor();
+  const body = {
+    messages: [
+      { role: "user", content: "plain string" },
+      { role: "assistant", tool_calls: [{ id: "c1", type: "function", function: { name: "f", arguments: "{}" } }] },
+    ],
+  };
+  const result = executor.transformRequest("claude-sonnet-4.6", body, true, {});
+  assert.equal(result.messages[0].content, "plain string");
+  assert.equal(result.messages[1].content, undefined);
+  assert.equal(result.messages[1].tool_calls[0].id, "c1");
+});
+
 test("GithubExecutor.buildHeaders prefers Copilot token and sets GitHub-specific headers", () => {
   const executor = new GithubExecutor();
   const headers = executor.buildHeaders(