feat(wizard): editable spec in step 2 — name, description, JSON schema, secrets

The wizard's confirm step is no longer read-only. Users can refine what Claude
parsed before committing to a build.

Backend:
- @bmm/types adds SpecEdit (tools[name,description,inputSchema] + requiredSecrets);
  CreateServerInput accepts an optional specEdit alongside previewId.
- Servers create endpoint: when specEdit is provided, loads cached spec from Redis,
  index-merges the edits in (keeping LLM-generated implementations untouched),
  re-validates via GeneratorSpec, re-runs the banned-pattern scan, overwrites the
  Redis cache so the worker reads the user's version. Refuses with
  preview_expired/tool_count_mismatch/banned_pattern on safety failures.
- New overwriteSpec() helper in preview-cache.

Frontend:
- Step 2 renders each tool as an editable card: name input, description textarea,
  JSON schema textarea with parse-on-keystroke validation (inline error if invalid).
- Required secrets list is editable: keys via uppercase-snake-case input, +Add /
  remove buttons, secret values kept in sync when keys are renamed.
- Reset-to-AI-suggestion button appears when edits are dirty.
- Pre-submit validation: schema must parse, secret keys must match UPPER_SNAKE_CASE,
  required secret values must be provided.
- Warning copy: 'Renaming parameters may require an Iterate after build — the
  existing impl references the original names.'

Verified end-to-end via browser smoke test: edited description + renamed tool
landed correctly in mcp_servers.tools_schema and in the live container at :4107.
Implementation field preserved from the original cached spec.

apps/api/src/routes/servers.ts

@@ -1,14 +1,21 @@
 import type { FastifyInstance } from 'fastify';
 import { z } from 'zod';
 import { and, builds, buildLogs, createDb, desc, eq, mcpServers, secrets } from '@bmm/db';
-import { CreateServerInput, IterateServerInput, BuildEvent, PreviewInput } from '@bmm/types';
+import {
+  CreateServerInput,
+  IterateServerInput,
+  BuildEvent,
+  PreviewInput,
+  GeneratorSpec,
+  type SpecEdit,
+} from '@bmm/types';
 import { generateSpec, SpecValidationError, BannedPatternError } from '@bmm/llm';
+import { cacheSpec, loadSpec, overwriteSpec } from '../lib/preview-cache.js';
 import { requireAuth } from '../plugins/session.js';
 import { getBuildQueue } from '../lib/queue.js';
 import { buildChannel, getSubscriber } from '../lib/redis.js';
 import { encryptSecret } from '../lib/crypto.js';
 import { audit } from '../lib/audit.js';
-import { cacheSpec } from '../lib/preview-cache.js';
 import { config } from '../config.js';
 
 const db = createDb();
@@ -68,7 +75,32 @@ export async function serverRoutes(app: FastifyInstance): Promise<void> {
     if (!parsed.success) {
       return reply.code(400).send({ error: 'invalid_input', issues: parsed.error.flatten() });
     }
-    const { name, slug, prompt, secrets: secretValues, previewId } = parsed.data;
+    const { name, slug, prompt, secrets: secretValues, previewId, specEdit } = parsed.data;
+
+    // If the user edited the spec in step 2 of the wizard, merge their edits into
+    // the cached spec (keeping the original tool implementations untouched).
+    if (specEdit) {
+      if (!previewId) {
+        return reply.code(400).send({ error: 'preview_id_required_with_edit' });
+      }
+      const cached = await loadSpec(previewId);
+      if (!cached) {
+        return reply.code(410).send({ error: 'preview_expired' });
+      }
+      const merged = mergeSpecEdit(cached, specEdit);
+      const validation = GeneratorSpec.safeParse(merged);
+      if (!validation.success) {
+        return reply
+          .code(422)
+          .send({ error: 'spec_invalid_after_edit', detail: validation.error.flatten() });
+      }
+      try {
+        rescanInjection(validation.data);
+      } catch (err) {
+        return reply.code(422).send({ error: 'banned_pattern', detail: (err as Error).message });
+      }
+      await overwriteSpec(previewId, validation.data);
+    }
 
     const existing = await db
       .select({ id: mcpServers.id })
@@ -313,3 +345,52 @@ export async function serverRoutes(app: FastifyInstance): Promise<void> {
     return reply.send({ ok: true });
   });
 }
+
+// ---- Spec-edit merge helpers ----
+
+const BANNED_PATTERNS = [
+  /\beval\s*\(/,
+  /\bnew\s+Function\s*\(/,
+  /\brequire\s*\(\s*['"]child_process['"]/,
+  /\bchild_process\b/,
+  /ignore\s+previous\s+instructions/i,
+  /disregard\s+(the\s+)?(above|previous)/i,
+];
+
+function rescanInjection(spec: GeneratorSpec): void {
+  for (const tool of spec.tools) {
+    for (const pattern of BANNED_PATTERNS) {
+      if (pattern.test(tool.implementation) || pattern.test(tool.description)) {
+        throw new Error(`banned_pattern_detected: ${pattern.source}`);
+      }
+    }
+  }
+}
+
+function mergeSpecEdit(cached: GeneratorSpec, edit: SpecEdit): GeneratorSpec {
+  // Index-based merge: user can edit tool name/description/inputSchema but cannot add or
+  // remove tools — that requires fresh generation. Implementation stays from cache so the
+  // LLM-generated code is preserved as-is.
+  if (edit.tools.length !== cached.tools.length) {
+    throw new Error(
+      `tool_count_mismatch: cached ${cached.tools.length}, edit ${edit.tools.length}`,
+    );
+  }
+  const mergedTools = edit.tools.map((editTool, i) => {
+    const original = cached.tools[i];
+    if (!original) {
+      throw new Error(`tool_index_missing: ${i}`);
+    }
+    return {
+      name: editTool.name,
+      description: editTool.description,
+      inputSchema: editTool.inputSchema,
+      implementation: original.implementation,
+    };
+  });
+  return {
+    ...cached,
+    tools: mergedTools,
+    requiredSecrets: edit.requiredSecrets,
+  };
+}