fix: resolve 500 errors from model returning trivial status objects (root cause + v0.2 prompt fix)

Two bugs were causing the model to return {"status":"ok"} / {"status":"ready"}
instead of structured reconstruction data, resulting in POST /api/analyse 500:

1. DOUBLE-WRAPPING BUG (lib/llm/provider.js):
   generateReconstruction() called buildPrompt(scenario) on input that was
   already a fully-built prompt string from analyseScenario(). This wrapped the
   v0.1 prompt (~5000+ chars) in another template layer, producing incomprehensible
   output that the model could not parse as structured JSON.
   Fix: Pass scenario through directly (it is ALREADY a built prompt).

2. MISSING JSON SPEC (prompts/reconstruct-v0.2.md):
   The v0.2 prompt template said 'matching the structure exactly' but never
   defined what that structure was. The model invented its own field names
   (input_classification, reasoning_mode, anchors) with snake_case instead of
   camelCase, which failed Zod validation -> 500 errors.
   Fix: Added explicit JSON schema section with exact key names, enum values,
   and nested structure matching the Zod validation layer.

Additionally:
- Refactored route to use analyseScenario from lib/analysis (centralized)
- Added lib/analysis.js with shared analysis logic
- Updated components to display promptVersion and validation errors
- Added lib/reconstruction/prompt.js v0.1/v0.2 versioning
- Added lib/reconstruction/schema.js v0.2 Zod schemas
- Added debug tool scripts, evaluation results, and comparison findings

app/api/analyse/route.js

@@ -1,16 +1,9 @@
-import { getConfig } from "@/lib/config";
-import { getProvider } from "@/lib/llm/provider";
-import { reconstructionSchema } from "@/lib/reconstruction/schema";
-
-const MAX_SCENARIO_LENGTH = 10000;
+import { analyseScenario, PROMPT_VERSIONS, DEFAULT_PROMPT_VERSION } from "@/lib/analysis";
 
 export async function POST(request) {
-  const startTime = Date.now();
-  let rawResponse = null;
-  
   try {
     const body = await request.json();
-    
+
     if (!body.scenario || typeof body.scenario !== "string") {
       return Response.json(
         { error: "Request must include a 'scenario' string field" },
@@ -18,83 +11,34 @@ export async function POST(request) {
       );
     }
 
-    const trimmed = body.scenario.trim();
-    
-    if (trimmed.length === 0) {
+    // Optional prompt version override
+    let promptVersion = DEFAULT_PROMPT_VERSION;
+    if (body.promptVersion && PROMPT_VERSIONS.includes(body.promptVersion)) {
+      promptVersion = body.promptVersion;
+    }
+
+    const result = await analyseScenario(body.scenario, { promptVersion });
+
+    if (!result.success) {
       return Response.json(
-        { error: "Scenario cannot be empty" },
-        { status: 400 }
+        { ...result, reconstruction: result.reconstruction || null },
+        { status: Number(result.statusCode) || 500 }
       );
     }
 
-    if (trimmed.length > MAX_SCENARIO_LENGTH) {
-      return Response.json(
-        { error: `Scenario must be under ${MAX_SCENARIO_LENGTH} characters` },
-        { status: 400 }
-      );
-    }
-
-    const configResult = getConfig();
-    if (!configResult.ok) {
-      return Response.json(
-        { error: "Invalid server configuration" },
-        { status: 500 }
-      );
-    }
-
-    const { OLLAMA_BASE_URL, OLLAMA_MODEL } = configResult.config;
-    const provider = getProvider();
-
-    // Attempt parse to capture raw for debugging
-    let reconstruction;
-    try {
-      reconstruction = await provider.generateReconstruction(trimmed, OLLAMA_MODEL);
-    } catch (e) {
-      return Response.json(
-        { 
-          error: e.message || "Unknown server error", 
-          responseDurationMs: Date.now() - startTime,
-          modelName: OLLAMA_MODEL,
-          validationStatus: "invalid",
-        },
-        { status: 500 }
-      );
-    }
-    
-    // Try to stringify for rawResponse display (safe even if it's already an object)
-    try {
-      rawResponse = JSON.stringify(reconstruction);
-    } catch {
-      rawResponse = String(reconstruction).slice(0, 2000);
-    }
-
-    const duration = Date.now() - startTime;
-
-    // Validate with Zod schema
-    const validationResult = reconstructionSchema.safeParse(reconstruction);
-
-    if (!validationResult.success) {
-      return Response.json({
-        reconstruction: null,
-        modelName: OLLAMA_MODEL,
-        responseDurationMs: duration,
-        validationStatus: "invalid",
-        rawResponse: rawResponse?.slice(0, 2000),
-        errors: validationResult.error.issues.map((i) => `${i.path.join(".")}: ${i.message}`),
-      });
-    }
-
     return Response.json({
-      reconstruction: validationResult.data,
-      modelName: OLLAMA_MODEL,
-      responseDurationMs: duration,
-      validationStatus: "valid",
-      rawResponse: rawResponse?.slice(0, 2000),
+      inputClassification: result.inputClassification,
+      reconstruction: result.reconstruction,
+      evidence: result.evidence,
+      nextQuestion: result.nextQuestion,
+      modelName: result.modelName,
+      responseDurationMs: result.responseDurationMs,
+      validationStatus: result.validationStatus,
+      promptVersion: result.promptVersion,
     });
   } catch (e) {
-    const duration = Date.now() - startTime;
     return Response.json(
-      { error: e.message || "Unknown server error", responseDurationMs: duration },
+      { error: e.message || "Unknown server error", responseDurationMs: 0 },
       { status: 500 }
     );
   }