feat: add debug_issue tool handler

src/tools/debug-issue.js

@@ -1 +1,78 @@
-// debug_issue tool handler.
+// Tool handler for the debug_issue MCP tool.
+
+import { validateToolInput } from "./schemas.js";
+import { checkContextBudget } from "../utils/context-budget.js";
+import { buildDebugIssuePrompt } from "../prompts/debug-issue.js";
+
+/**
+ * Handle the debug_issue MCP tool.
+ *
+ * Orchestration order: validate -> config -> budget -> prompt -> client -> response.
+ * All external dependencies injected via deps. Internal utilities imported directly.
+ * No throws escape — all paths return structured results.
+ *
+ * @param {unknown} input
+ *   Raw tool input per ARCHITECTURE.md §7 schema.
+ * @param {{
+ *   loadConfig: () => object,
+ *   createOpenAIClient: (config: object) => any,
+ *   sendOpenAIResponse: (client: any, params: object) => Promise<any>
+ * }} deps
+ *   Injected external dependencies.
+ * @returns {Promise<{ ok: true, answer: string, warnings: string[] } | { ok: false, error: string, warnings: string[] }>}
+ */
+export async function handleDebugIssue(input, deps) {
+  // --- 1. Validate input (before anything else) ---
+
+  const validation = validateToolInput(input);
+  if (!validation.ok) {
+    return { ok: false, error: validation.errors.join(" | "), warnings: [] };
+  }
+
+  // --- 2. Load config ---
+
+  let config;
+  try {
+    config = deps.loadConfig();
+  } catch (err) {
+    return { ok: false, error: String(err), warnings: [] };
+  }
+
+  // --- 3. Context budget check ---
+
+  const budget = checkContextBudget(validation.data, config);
+  if (!budget.ok) {
+    return { ok: false, error: budget.error, warnings: budget.warnings };
+  }
+
+  // --- 4. Build prompt ---
+
+  const promptMessages = buildDebugIssuePrompt(budget.input);
+
+  // --- 5. Create OpenAI client ---
+
+  let client;
+  try {
+    client = deps.createOpenAIClient(config);
+  } catch (err) {
+    return { ok: false, error: String(err), warnings: [] };
+  }
+
+  // --- 6. Send to OpenAI ---
+
+  let aiResult;
+  try {
+    aiResult = await deps.sendOpenAIResponse(client, {
+      input: [{ role: "system", content: promptMessages }],
+      model: config.openaiModel,
+      temperature: config.temperature,
+      maxOutputTokens: config.maxOutputTokens,
+    });
+  } catch (err) {
+    return { ok: false, error: String(err), warnings: [] };
+  }
+
+  // --- 7. Success ---
+
+  return { ok: true, answer: aiResult.content, warnings: budget.warnings };
+}