feat(llm): propagate cancellation through reconstruction providers

lib/llm/provider.js

@@ -290,7 +290,27 @@ export function __resetChatSupportForTests() {
   _chatSupported = null;
 }
 
-async function detectChatSupport(baseUrl, modelName) {
+function isAbortError(error) {
+  return error?.name === "AbortError";
+}
+
+function createRequestAbortController(signal, timeoutMs = 300000) {
+  const controller = new AbortController();
+  const abortFromCaller = () => controller.abort();
+  if (signal?.aborted) controller.abort();
+  else signal?.addEventListener("abort", abortFromCaller, { once: true });
+  const timeout = setTimeout(() => controller.abort(), timeoutMs);
+
+  return {
+    signal: controller.signal,
+    dispose() {
+      clearTimeout(timeout);
+      signal?.removeEventListener("abort", abortFromCaller);
+    },
+  };
+}
+
+async function detectChatSupport(baseUrl, modelName, signal) {
   if (_chatSupported !== null) return _chatSupported;
   
   try {
@@ -302,6 +322,7 @@ async function detectChatSupport(baseUrl, modelName) {
         messages: [{ role: "user", content: "test" }],
         stream: false,
       }),
+      signal,
     });
     
     if (res.ok) {
@@ -314,7 +335,8 @@ async function detectChatSupport(baseUrl, modelName) {
       await res.text();
       _chatSupported = false;
     }
-  } catch {
+  } catch (error) {
+    if (isAbortError(error) && signal?.aborted) throw error;
     _chatSupported = false;
   }
   
@@ -322,7 +344,7 @@ async function detectChatSupport(baseUrl, modelName) {
 }
 
 class OllamaLlmProvider {
-  async generateReconstruction(scenario, modelName, outputSchema) {
+  async generateReconstruction(scenario, modelName, outputSchema, { signal } = {}) {
     // scenario is ALREADY a fully-built prompt text (built by analyseScenario).
     // Do NOT call buildPrompt() again — that would double-wrap the prompt.
     const prompt = scenario;
@@ -345,18 +367,19 @@ class OllamaLlmProvider {
     // Step 1: Detect whether /api/chat exists (cache result)
     // ================================================================
     try {
-      chatSupported = await detectChatSupport(baseUrl, modelName);
-    } catch { /* failed silently — defaults to false */ }
+      chatSupported = await detectChatSupport(baseUrl, modelName, signal);
+    } catch (error) {
+      if (isAbortError(error) && signal?.aborted) throw error;
+      // Failed silently — defaults to false.
+    }
     providerExecution.chatCapabilityDetected = chatSupported;
 
     // ================================================================
     // Step 2: Try /api/chat if supported with the supplied or reconstruction schema
     // ================================================================
     if (chatSupported) {
+      const requestAbort = createRequestAbortController(signal);
       try {
-        const controller = new AbortController();
-        const timeout = setTimeout(() => controller.abort(), 300000); // 5 min for reconstruction
-
         apiUsed = "/api/chat";
         providerExecution.chatRequestAttempted = true;
         const res = await fetch(`${baseUrl}/api/chat`, {
@@ -368,11 +391,9 @@ class OllamaLlmProvider {
             stream: false,
             format: outputSchema ?? reconstructionJsonSchema,
           }),
-          signal: controller.signal,
+          signal: requestAbort.signal,
         });
 
-        clearTimeout(timeout);
-
         if (res.ok) {
           providerExecution.chatRequestSucceeded = true;
           fullResponseData = await res.json();
@@ -384,7 +405,9 @@ class OllamaLlmProvider {
           await res.text();
         }
       } catch (e) {
-        if (!e.message.includes("abort")) { /* non-fatal */ }
+        if (isAbortError(e)) throw e;
+      } finally {
+        requestAbort.dispose();
       }
     }
 
@@ -393,10 +416,8 @@ class OllamaLlmProvider {
     // Use a long timeout — cold starts can take 2-4 minutes for large models.
     // ================================================================
     if (rawResponse == null || rawResponse === "") {
+      const requestAbort = createRequestAbortController(signal);
       try {
-        const controller = new AbortController();
-        const timeout = setTimeout(() => controller.abort(), 300000); // 5 min for cold start
-
         apiUsed = "/api/generate"; // set BEFORE the request so we know which API failed
         providerExecution.generateRequestAttempted = true;
 
@@ -410,11 +431,9 @@ class OllamaLlmProvider {
             // No format:json — older Ollama doesn't support it on /api/generate either.
             // We rely on the strong prompt instruction above instead.
           }),
-          signal: controller.signal,
+          signal: requestAbort.signal,
         });
 
-        clearTimeout(timeout);
-
         if (!res.ok) {
           const text = await res.text().catch(() => "");
           throw new Error(`/api/generate returned ${res.status}: ${text.slice(0, 500)}`);
@@ -439,7 +458,7 @@ class OllamaLlmProvider {
             `- Use a smaller model (e.g., llama3.1 instead of llama3.1:70b)\n` +
             `- Check Ollama logs: \`ollama serve\` or look at your system logs`
           );
-          if (e?.name === "AbortError" || e instanceof TypeError) {
+          if (isAbortError(e) || e instanceof TypeError) {
             error.code = "PROVIDER_UNAVAILABLE";
           }
           error.providerApiPath = apiUsed;
@@ -447,6 +466,8 @@ class OllamaLlmProvider {
           throw error;
         }
         throw e;
+      } finally {
+        requestAbort.dispose();
       }
     }
 
@@ -525,7 +546,7 @@ class OpenAIReconstructionProvider {
     this.fetchImpl = fetchImpl;
   }
 
-  async generateReconstruction(prompt, modelName = "gpt-5.6-terra", outputSchema) {
+  async generateReconstruction(prompt, modelName = "gpt-5.6-terra", outputSchema, { signal } = {}) {
     if (!this.apiKey) throw new Error("OPENAI_API_KEY is not set");
     const structuredOutputSchema = outputSchema
       ? createOpenAIStrictSchema(outputSchema, null)
@@ -551,6 +572,7 @@ class OpenAIReconstructionProvider {
           format,
         },
       }),
+      signal,
     });
 
     if (!response.ok) {