cleanup: bump qwen2.5 → qwen3.5:latest in active defaults

stronger local rung is now the small-model-pipeline tier-1 default
across both Rust legacy + Go rewrite (cf. golangLAKEHOUSE phase 1).
same JSON-clean property as qwen2.5, more capacity. ollama still
serves both side-by-side; rollback is a 4-line revert if a workload
regresses.

active-default sites:
- lakehouse.toml [ai] gen_model + rerank_model → qwen3.5:latest
- mcp-server/observer.ts diagnose call (Phase 44 /v1/chat path) → qwen3.5:latest
- mcp-server/index.ts model roster doc → qwen3.5:latest first
- crates/vectord/src/rag.rs ContinuableOpts + RagResponse.model → qwen3.5:latest

skipped: execution_loop/mod.rs comments describing historic qwen2.5
tool_call quirks — those are documentation of past behavior, not
active defaults. data/_catalog/profiles/*.json are runtime-generated
(gitignored), not in scope for tracked changes.

cargo check -p vectord: clean. no behavioral change in the audit
pipeline — same JSON-clean local model, same think=Some(false)
posture, just stronger upstream.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

mcp-server/index.ts

@@ -313,9 +313,9 @@ ${(buckets as any[] || []).map((b: any) => `- ${b.name}: ${b.backend} (${b.reach
 - Ollama: :11434
 
 ## Available Models
+- qwen3.5:latest: stronger local rung, JSON-clean (default for gen + rerank)
 - qwen3: 8.2B, 40K context, thinking+tools (best for reasoning)
-- qwen2.5: 7B, 8K context (best for fast SQL generation)
-- mistral: 7B, 8K context (general generation)
+- qwen2.5: 7B, 8K context (legacy — 2026-04 era comparison runs only)
 - nomic-embed-text: 137M (embedding, automatic)
 `;
   return { contents: [{ uri: uri.href, mimeType: "text/plain", text }] };

mcp-server/observer.ts

@@ -146,15 +146,16 @@ async function persistOp(op: ObservedOp) {
 // ─── LLM Team escalation (code_review mode) ───
 //
 // When recent failures on a single sig_hash cross a threshold the
-// local qwen2.5 analysis is probably insufficient. J's 2026-04-24
+// local-model analysis is probably insufficient. J's 2026-04-24
 // direction: "the observer would trigger to give more context" —
 // route failure clusters to LLM Team's specialized code_review mode
 // (via /api/run) so richer structured signal lands in the KB for
 // scrum + auditor + playbook memory to consume next pass.
 //
-// Non-destructive: runs in parallel to the existing qwen2.5 analysis,
-// never replaces it. Writes to data/_kb/observer_escalations.jsonl
-// as a dedicated audit surface.
+// Non-destructive: runs in parallel to the existing local diagnose
+// call (qwen3.5:latest after the 2026-04-30 bump), never replaces
+// it. Writes to data/_kb/observer_escalations.jsonl as a dedicated
+// audit surface.
 
 const LLM_TEAM = process.env.LH_LLM_TEAM_URL ?? "http://localhost:5000";
 const LLM_TEAM_ESCALATIONS = "/home/profit/lakehouse/data/_kb/observer_escalations.jsonl";
@@ -542,7 +543,7 @@ async function analyzeErrors() {
   if (failures.length === 0) return;
 
   // NEW 2026-04-24: escalate recurring sig_hash clusters to LLM Team
-  // code_review mode. Runs in parallel to the local qwen2.5 analysis
+  // code_review mode. Runs in parallel to the local diagnose call
   // below — non-blocking, richer downstream signal for scrum/auditor.
   maybeEscalate(failures).catch(() => {});
 
@@ -552,13 +553,14 @@ async function analyzeErrors() {
 
   // Ask local model to diagnose. Phase 44 migration (2026-04-27):
   // /v1/chat instead of legacy /ai/generate so /v1/usage tracks the
-  // call + Langfuse traces it. Same upstream model (qwen2.5 local).
+  // call + Langfuse traces it. 2026-04-30 model bump: qwen2.5 →
+  // qwen3.5:latest to match the small-model-pipeline local-tier default.
   try {
     const resp = await fetch(`${LAKEHOUSE}/v1/chat`, {
       method: "POST",
       headers: { "Content-Type": "application/json" },
       body: JSON.stringify({
-        model: "qwen2.5",
+        model: "qwen3.5:latest",
         provider: "ollama",
         messages: [{
           role: "user",