From 9b78d475becf58cb33a3cd049672c15eda1017b3 Mon Sep 17 00:00:00 2001
From: diegosouzapw <8016841+diegosouzapw@users.noreply.github.com>
Date: Tue, 15 Sep 2026 15:39:58 -0300
Subject: [PATCH] fix(providers): stop zed-hosted claude-haiku-4-5 thinking
 from inflating max_tokens (#13364)

zed-hosted's passthrough catalog exposes the short hyphenated id
"claude-haiku-4-5", but modelSpecs' registered alias is the dotted
"claude-haiku-4.5" - a spelling mismatch, not a missing spec. With no
zed-hosted entry in PROVIDER_MODEL_ALIASES, capMaxOutputTokens() resolved
no cap for this model, so fitThinkingToMaxTokens added the response
headroom directly to the requested thinking budget (32000 + 131072 =
163072) instead of fitting under the real 64000 output cap - Zed's proxy
rejects the inflated request. Same class of fix already applied for the
"kiro" provider in the same table.

Regression test: tests/unit/issue-13364-zed-hosted-haiku-thinking-inflation.test.ts

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
---
 ...364-zed-hosted-haiku-thinking-inflation.md |  1 +
 open-sse/services/model.ts                    |  8 ++++
 ...ed-hosted-haiku-thinking-inflation.test.ts | 39 +++++++++++++++++++
 3 files changed, 48 insertions(+)
 create mode 100644 changelog.d/fixes/13364-zed-hosted-haiku-thinking-inflation.md
 create mode 100644 tests/unit/issue-13364-zed-hosted-haiku-thinking-inflation.test.ts

diff --git a/changelog.d/fixes/13364-zed-hosted-haiku-thinking-inflation.md b/changelog.d/fixes/13364-zed-hosted-haiku-thinking-inflation.md
new file mode 100644
index 000000000000..9b6ec3a649d5
--- /dev/null
+++ b/changelog.d/fixes/13364-zed-hosted-haiku-thinking-inflation.md
@@ -0,0 +1 @@
+- **fix(providers):** stop zed-hosted `claude-haiku-4-5` extended-thinking requests from inflating `max_tokens` past the model's real 64000 output cap (#13364) — thanks @ThiagoMafra-Integrare
diff --git a/open-sse/services/model.ts b/open-sse/services/model.ts
index ec0080ef8387..ad90495558b2 100644
--- a/open-sse/services/model.ts
+++ b/open-sse/services/model.ts
@@ -102,6 +102,14 @@ const PROVIDER_MODEL_ALIASES: ProviderModelAliasMap = {
     "claude-sonnet-4-5": "claude-sonnet-4.5",
     "claude-haiku-4-5": "claude-haiku-4.5",
   },
+  // #13364: zed-hosted's passthrough catalog exposes short hyphenated Claude ids
+  // that don't match modelSpecs' dotted canonical alias, so capMaxOutputTokens()
+  // resolves no cap and thinking+tools requests inflate max_tokens unbounded.
+  // Scoped to claude-haiku-4-5 (the reported/reproduced model) — add Sonnet/Opus
+  // entries only once confirmed against the live Zed catalog.
+  "zed-hosted": {
+    "claude-haiku-4-5": "claude-haiku-4.5",
+  },
 };
 
 const CROSS_PROXY_MODEL_ALIASES: Record<string, string> = {
diff --git a/tests/unit/issue-13364-zed-hosted-haiku-thinking-inflation.test.ts b/tests/unit/issue-13364-zed-hosted-haiku-thinking-inflation.test.ts
new file mode 100644
index 000000000000..43df02bb6ebe
--- /dev/null
+++ b/tests/unit/issue-13364-zed-hosted-haiku-thinking-inflation.test.ts
@@ -0,0 +1,39 @@
+import { test } from "node:test";
+import assert from "node:assert/strict";
+import { openaiToClaudeRequest } from "../../open-sse/translator/request/openai-to-claude.ts";
+
+// #13364 — zed-hosted/claude-haiku-4-5: extended thinking + tools inflates
+// max_tokens to 163072 (> Anthropic's real 64000 cap for this model), causing
+// Zed's proxy to reject the request in-stream with:
+//   "max_tokens: 163072 > 64000, which is the maximum allowed number of
+//    output tokens for claude-haiku-4-5-20251001"
+//
+// Root cause: zed-hosted's passthrough catalog exposes the short hyphenated id
+// "claude-haiku-4-5", but modelSpecs' registered alias for that model is the
+// dotted "claude-haiku-4.5" — a spelling mismatch (not a missing spec) means
+// capMaxOutputTokens() resolves no cap for zed-hosted, so fitThinkingToMaxTokens
+// adds the requested budget instead of fitting it under the model's real ceiling.
+test("zed-hosted/claude-haiku-4-5 thinking+tools must not inflate max_tokens past the real 64000 output cap", () => {
+  const body = {
+    model: "claude-haiku-4-5",
+    max_tokens: 16000,
+    reasoning_effort: "high", // what claude-to-openai produces for the client's budget_tokens:15999
+    tools: [
+      {
+        type: "function",
+        function: { name: "read_file", parameters: { type: "object", properties: {} } },
+      },
+    ],
+    messages: [{ role: "user", content: "hello" }],
+  };
+  const credentials = { _provider: "zed-hosted" };
+
+  const result = openaiToClaudeRequest("claude-haiku-4-5", body, false, credentials);
+  const claudeHaiku45OutputCap = 64000; // src/shared/constants/modelSpecs.ts "claude-haiku-4-5-20251001"
+
+  assert.ok(
+    (result.max_tokens as number) <= claudeHaiku45OutputCap,
+    `max_tokens (${result.max_tokens}) must not exceed the model's real output cap ` +
+      `(${claudeHaiku45OutputCap}) — Anthropic/Zed rejects the request otherwise`
+  );
+});