feat: DeepSeek API integration + Whale lift (hooks, tool repair, MCP permissions, token tracking)

DeepSeek API:
- @ai-sdk/deepseek provider replaces openai-compatible for deepseek-* models
- Token tracking: cache_hit/reasoning tokens flow API → DB → WS frames → UI
- thinking effort levels (off/low/medium/high/xhigh/max) via AGENTS.md frontmatter
- V4 models: deepseek-v4-flash, deepseek-v4-pro
- Wired for both chat and coder panes

Whale lifts:
- Tool input repair (schema-based type coercion, markdown link unwrapping)
- Hooks system (6 lifecycle events, shell exec, JSON stdin/stdout contract)
- Per-MCP-server permissions (allow/ask/deny)
- token tracking UI (cache N, think N in message stats line)

Infra:
- New DB columns: messages.cache_tokens, messages.reasoning_tokens
- New WS frame fields: cache_tokens, reasoning_tokens on message_complete
- coder provider snapshot merges DeepSeek models alongside llama-swap

apps/server/src/services/model-context.ts

@@ -37,7 +37,18 @@ export function configureModelContext(opts: { llamaSwapUrl: string }): void {
   llamaSwapUrl = opts.llamaSwapUrl;
 }
 
+// vDeepSeek: DeepSeek models don't have a /upstream/<model>/props endpoint.
+// Return a reasonable default context so compaction estimates work.
+const DEEPSEEK_DEFAULT_N_CTX = 131_072;
+const DEEPSEEK_MODEL_PREFIX = 'deepseek-';
+
 export async function getModelContext(model: string): Promise<ModelContext | null> {
+  // vDeepSeek: DeepSeek models have no /upstream/<model>/props. Use a static
+  // default so compaction doesn't fall to the buffer-only path with tiny limits.
+  if (model.startsWith(DEEPSEEK_MODEL_PREFIX)) {
+    return { n_ctx: DEEPSEEK_DEFAULT_N_CTX };
+  }
+
   // 1. Positive cache hit — no TTL check, model n_ctx is invariant.
   const pos = positiveCache.get(model);
   if (pos) return pos;