fix(proxy): keep tool_use stop_reason when the stream ends with [DONE]

package.json

@@ -38,7 +38,7 @@
     "desktop:package:win": "npm run dist:win --workspace @blockrun/franklin-desktop",
     "dev": "tsc --watch",
     "start": "node dist/index.js",
-    "test": "npm run build && node --test --test-concurrency=4 --test-reporter=spec test/local.mjs test/api-key.local.mjs test/solana-migration.local.mjs test/serve-security.local.mjs test/skills.local.mjs test/skills-management.local.mjs test/glob-responsive.local.mjs test/desktop-auto-routing.local.mjs test/desktop-questions.local.mjs test/desktop-question-flow.local.mjs test/desktop-input.local.mjs test/desktop-image-flow.local.mjs test/repair.mjs test/model-resolver.mjs test/exa.local.mjs test/audit-batch.local.mjs test/polymarket.local.mjs test/market.local.mjs test/hooks.local.mjs test/scheduler.local.mjs test/trade-plan.local.mjs test/goal.local.mjs test/memory.local.mjs test/agent-host.local.mjs test/reservation.local.mjs test/model-catalog.local.mjs test/arc.local.mjs test/subprocess-env.local.mjs test/withdraw.local.mjs test/orders.local.mjs test/payment-hold.local.mjs test/experience.local.mjs",
+    "test": "npm run build && node --test --test-concurrency=4 --test-reporter=spec test/local.mjs test/api-key.local.mjs test/solana-migration.local.mjs test/serve-security.local.mjs test/skills.local.mjs test/skills-management.local.mjs test/glob-responsive.local.mjs test/desktop-auto-routing.local.mjs test/desktop-questions.local.mjs test/desktop-question-flow.local.mjs test/desktop-input.local.mjs test/desktop-image-flow.local.mjs test/repair.mjs test/model-resolver.mjs test/exa.local.mjs test/audit-batch.local.mjs test/polymarket.local.mjs test/market.local.mjs test/hooks.local.mjs test/scheduler.local.mjs test/trade-plan.local.mjs test/goal.local.mjs test/memory.local.mjs test/agent-host.local.mjs test/reservation.local.mjs test/model-catalog.local.mjs test/arc.local.mjs test/subprocess-env.local.mjs test/withdraw.local.mjs test/orders.local.mjs test/payment-hold.local.mjs test/experience.local.mjs test/sse-translator.local.mjs",
     "test:e2e": "npm run build && node --test --test-reporter=spec test/e2e.mjs",
     "e2e:polymarket:readonly": "npm run build && node scripts/polymarket-e2e-readonly.mjs",
     "test:free-models": "npm run build && node --test --test-reporter=spec test/free-model-matrix.mjs",

src/proxy/sse-translator.ts

@@ -15,6 +15,7 @@ interface TranslatorState {
   thinkingBlockActive: boolean;
   textBlockActive: boolean;
   messageStarted: boolean;
+  stopReasonEmitted: boolean;
   inputTokens: number;
   outputTokens: number;
 }
@@ -38,6 +39,7 @@ export class SSETranslator {
       thinkingBlockActive: false,
       textBlockActive: false,
       messageStarted: false,
+      stopReasonEmitted: false,
       inputTokens: 0,
       outputTokens: 0,
     };
@@ -69,13 +71,17 @@ export class SSETranslator {
     for (const event of events) {
       if (event.data === '[DONE]') {
         translated.push(...this.closeActiveBlocks());
-        translated.push(
-          this.formatSSE('message_delta', {
-            type: 'message_delta',
-            delta: { stop_reason: 'end_turn', stop_sequence: null },
-            usage: { output_tokens: this.state.outputTokens },
-          })
-        );
+        // A finish_reason chunk already emitted the real stop_reason (e.g.
+        // tool_use); a second message_delta here would overwrite it.
+        if (!this.state.stopReasonEmitted) {
+          translated.push(
+            this.formatSSE('message_delta', {
+              type: 'message_delta',
+              delta: { stop_reason: 'end_turn', stop_sequence: null },
+              usage: { output_tokens: this.state.outputTokens },
+            })
+          );
+        }
         translated.push(this.formatSSE('message_stop', { type: 'message_stop' }));
         continue;
       }
@@ -230,6 +236,7 @@ export class SSETranslator {
             : choice.finish_reason === 'stop'
               ? 'end_turn'
               : choice.finish_reason;
+        this.state.stopReasonEmitted = true;
         translated.push(
           this.formatSSE('message_delta', {
             type: 'message_delta',

test/sse-translator.local.mjs

@@ -0,0 +1,62 @@
+import { describe, it } from 'node:test';
+import assert from 'node:assert/strict';
+import { SSETranslator } from '../dist/proxy/sse-translator.js';
+
+function sse(obj) {
+  return `data: ${typeof obj === 'string' ? obj : JSON.stringify(obj)}\n\n`;
+}
+
+function stopReasons(output) {
+  return output
+    .split('\n\n')
+    .filter((e) => e.startsWith('event: message_delta'))
+    .map((e) => JSON.parse(e.split('data: ')[1]).delta.stop_reason);
+}
+
+function run(finishReason) {
+  const t = new SSETranslator('test-model');
+  const out = [];
+  const feed = (c) => out.push(t.processChunk(c) ?? '');
+  feed(sse({ choices: [{ index: 0, delta: { role: 'assistant', content: 'hi' } }] }));
+  if (finishReason === 'tool_calls') {
+    feed(
+      sse({
+        choices: [
+          {
+            index: 0,
+            delta: {
+              tool_calls: [
+                { index: 0, id: 'call_1', type: 'function', function: { name: 'Read', arguments: '{}' } },
+              ],
+            },
+          },
+        ],
+      })
+    );
+  }
+  feed(sse({ choices: [{ index: 0, delta: {}, finish_reason: finishReason }] }));
+  feed(sse('[DONE]'));
+  return out.join('');
+}
+
+describe('SSETranslator stop_reason', () => {
+  it('keeps tool_use when [DONE] follows a tool_calls finish', () => {
+    const output = run('tool_calls');
+    assert.deepEqual(stopReasons(output), ['tool_use']);
+    assert.ok(output.includes('event: message_stop'));
+  });
+
+  it('emits a single end_turn for a normal stop', () => {
+    const output = run('stop');
+    assert.deepEqual(stopReasons(output), ['end_turn']);
+    assert.ok(output.includes('event: message_stop'));
+  });
+
+  it('falls back to end_turn when [DONE] arrives without a finish_reason', () => {
+    const t = new SSETranslator('test-model');
+    t.processChunk(sse({ choices: [{ index: 0, delta: { content: 'hi' } }] }));
+    const output = t.processChunk(sse('[DONE]')) ?? '';
+    assert.deepEqual(stopReasons(output), ['end_turn']);
+    assert.ok(output.includes('event: message_stop'));
+  });
+});