fix(stop+stability): stop button interrupts live generation; classifier, prompt + preview pane improvements

Stop button fix:
- Plumb AbortSignal end-to-end: callVibnChat → Gemini SDK (config.abortSignal) / OpenAI fetch → executeMcpTool (/api/mcp fetch)
- Treat abort as clean user stop (not fatal error); partial reply persisted with '(stopped by user)'

Classifier fix:
- Add timeout/gateway/5xx/connection-error vocabulary to diagnose intent
- Prevents 'I get a gateway timeout' from falling through to feature_build (40 rounds) and looping

Prompt / agent behaviour:
- Render verification is now scope-aware: small edits stop at green healthCheck; no browser_console/curl audit on healthy server
- Sanitize stale '### Phase Checkpoint' walls from loaded history so old threads stop biasing new turns
- Next.js dev command updated to --no-turbopack for container stability (per-route lazy compile caused cold-start 503s)
- New public page prompt: agent checks middleware allowlist in the same turn
- Scope discipline and QA-tool gating carried forward from prior session

Code cleanup:
- Remove duplicate AgentPhase declaration (TS2440)
- Remove dead checkpoint emit branch and orphan 'checkpoint' phase value
- Remove unused MAX_TOOL_ROUNDS constant

Preview pane (build status):
- 4-state machine: initial-load / building (with elapsed timer) / build-failed / not-running
- pollMs 0 → 5 000ms so dev-server recovery and build completion auto-update without refresh
- anatomy route + use-anatomy type: inFlightBuild gains createdAt for elapsed timer

vibn-frontend/lib/ai/gemini-chat.ts

@@ -109,6 +109,8 @@ export async function callGeminiChat(opts: {
   tools?: ToolDefinition[];
   temperature?: number;
   includeThoughts?: boolean;
+  /** Cancels the in-flight generation when the user clicks Stop. */
+  signal?: AbortSignal;
 }): Promise<{
   text: string;
   thoughts: string;
@@ -129,6 +131,10 @@ export async function callGeminiChat(opts: {
     const fns = toGeminiFunctions(opts.tools ?? []);
     if (fns) config.tools = fns;
 
+    // Forward the request abort signal so a Stop click cancels the actual
+    // Gemini generation instead of only short-circuiting the next round.
+    if (opts.signal) config.abortSignal = opts.signal;
+
     console.log("\n========================================================");
     console.log("➡️ [GEMINI API REQUEST]");
     console.log("========================================================");
@@ -227,11 +233,16 @@ export async function callGeminiChat(opts: {
       finishReason: response.candidates?.[0]?.finishReason,
     };
   } catch (error) {
+    const aborted =
+      opts.signal?.aborted ||
+      (error instanceof Error && error.name === "AbortError");
     return {
       text: "",
       thoughts: "",
       toolCalls: [],
-      error: `GoogleGenAI error: ${error instanceof Error ? error.message : String(error)}`,
+      error: aborted
+        ? "aborted"
+        : `GoogleGenAI error: ${error instanceof Error ? error.message : String(error)}`,
     };
   }
 }

vibn-frontend/lib/ai/openai-compatible-chat.ts

@@ -257,6 +257,8 @@ export async function callOpenAiCompatibleChat(opts: {
   temperature?: number;
   /** Unused for OpenAI-compat; kept for call-site symmetry */
   includeThoughts?: boolean;
+  /** Cancels the in-flight request when the user clicks Stop. */
+  signal?: AbortSignal;
 }): Promise<{
   text: string;
   thoughts: string;
@@ -330,13 +332,18 @@ export async function callOpenAiCompatibleChat(opts: {
         Authorization: `Bearer ${apiKey}`,
       },
       body: JSON.stringify(body),
+      signal: opts.signal,
     });
   } catch (e) {
+    const aborted =
+      opts.signal?.aborted || (e instanceof Error && e.name === "AbortError");
     return {
       text: "",
       thoughts: "",
       toolCalls: [],
-      error: `Network error: ${e instanceof Error ? e.message : String(e)}`,
+      error: aborted
+        ? "aborted"
+        : `Network error: ${e instanceof Error ? e.message : String(e)}`,
     };
   }
 

vibn-frontend/lib/ai/vibn-chat-model.ts

@@ -12,9 +12,9 @@
  *   Optional: VIBN_OPENAI_COMPATIBLE_MODEL (default deepseek-chat)
  */
 
-import type { ChatMessage, ToolDefinition } from './gemini-chat';
-import { callGeminiChat } from './gemini-chat';
-import { callOpenAiCompatibleChat } from './openai-compatible-chat';
+import type { ChatMessage, ToolDefinition } from "./gemini-chat";
+import { callGeminiChat } from "./gemini-chat";
+import { callOpenAiCompatibleChat } from "./openai-compatible-chat";
 
 export type VibnChatCallOpts = {
   systemPrompt: string;
@@ -22,11 +22,13 @@ export type VibnChatCallOpts = {
   tools?: ToolDefinition[];
   temperature?: number;
   includeThoughts?: boolean;
+  /** Forwarded to the provider so a Stop click cancels the live request. */
+  signal?: AbortSignal;
 };
 
 export async function callVibnChat(opts: VibnChatCallOpts) {
-  const p = (process.env.VIBN_CHAT_PROVIDER || 'gemini').toLowerCase().trim();
-  if (p === 'deepseek' || p === 'openai_compatible') {
+  const p = (process.env.VIBN_CHAT_PROVIDER || "gemini").toLowerCase().trim();
+  if (p === "deepseek" || p === "openai_compatible") {
     return callOpenAiCompatibleChat(opts);
   }
   return callGeminiChat(opts);

vibn-frontend/lib/ai/vibn-tools.ts

@@ -12,13 +12,7 @@ import type { ToolDefinition } from "./gemini-chat";
 
 const GITHUB_TOKEN = process.env.GITHUB_TOKEN || "";
 
-export type AgentPhase =
-  | "plan"
-  | "recon"
-  | "checkpoint"
-  | "execute"
-  | "verify"
-  | "final";
+export type AgentPhase = "plan" | "recon" | "execute" | "verify" | "final";
 
 export type TurnIntent =
   | "conversational"
@@ -77,7 +71,12 @@ export function filterToolsForPhase(
   phase: AgentPhase,
   intent: TurnIntent,
 ): ToolDefinition[] {
-  if (phase === "recon" || phase === "verify") {
+  // `verify` stays read-only: when the agent is checking its work it should
+  // inspect, not start new edits. `recon` and `execute` both expose the full
+  // toolset so the agent can read AND edit directly in one fluid turn — the
+  // old read-only `recon` paired with the (now-removed) forced checkpoint to
+  // gate editing, which made the agent plan and stall instead of acting.
+  if (phase === "verify") {
     return tools.filter(
       (t) =>
         READ_ONLY_TOOLS.has(t.name) ||
@@ -85,10 +84,7 @@ export function filterToolsForPhase(
         t.name === "browser_navigate",
     );
   }
-  if (phase === "execute") {
-    return tools; // All tools allowed
-  }
-  return tools; // Default fallback
+  return tools; // recon + execute: all tools allowed
 }
 
 export const VIBN_TOOL_DEFINITIONS: ToolDefinition[] = [
@@ -1887,6 +1883,7 @@ export async function executeMcpTool(
   mcpToken: string,
   baseUrl: string,
   projectId?: string,
+  signal?: AbortSignal,
 ): Promise<string> {
   if (toolName === "github_search") return executeGithubSearch(args);
   if (toolName === "github_file") return executeGithubFile(args);
@@ -1923,6 +1920,7 @@ export async function executeMcpTool(
       method: "POST",
       headers,
       body: JSON.stringify({ action, params }),
+      signal,
     });
     const data = await res.json();
     return JSON.stringify(data.result ?? data.error ?? data, null, 2).slice(
@@ -1930,8 +1928,14 @@ export async function executeMcpTool(
       8000,
     );
   } catch (e) {
+    const aborted =
+      signal?.aborted || (e instanceof Error && e.name === "AbortError");
     return JSON.stringify({
-      error: e instanceof Error ? e.message : String(e),
+      error: aborted
+        ? "aborted by user"
+        : e instanceof Error
+          ? e.message
+          : String(e),
     });
   }
 }