fix(daemon): guard runTask with per-model thinking_level validator (MUL-2339)

ValidateThinkingLevel existed but had no call site — `task.Agent.
ThinkingLevel` flowed straight into ExecOptions, so `xhigh` configured
on a non-Opus Claude model, or API-side stale values that escaped the
provider enum gate, would be injected anyway.

Run the validator before building ExecOptions. Invalid combinations
log a warning and drop the level instead of failing the task: the
agent still runs, just at the runtime's default reasoning effort.
Discovery errors fail open (keep the level, let the CLI surface any
objection) so a transient `claude --help` failure can't strand work.

Empty model is forwarded as-is; the validator resolves it to the
provider's default model internally per the cross-package contract.

Co-authored-by: multica-agent <github@multica.ai>

server/internal/daemon/daemon.go

@@ -2439,6 +2439,34 @@ func (d *Daemon) runTask(ctx context.Context, task Task, provider string, slot i
 	if task.Agent != nil {
 		thinkingLevel = task.Agent.ThinkingLevel
 	}
+	// Per-model guard: the server validates the literal token against the
+	// provider's enum, but per-model gaps (Claude's `xhigh` on a non-Opus
+	// model, Codex's per-model `supported_reasoning_levels`) only resolve
+	// here, against the daemon's local CLI catalog. Invalid combinations
+	// log a warning and drop the level rather than failing the task, so a
+	// stale persisted value never blocks execution. Empty model is passed
+	// through unchanged — ValidateThinkingLevel resolves it to the
+	// provider's default model internally so default-model tasks aren't
+	// misjudged. Discovery errors fail open: if we can't list models, we
+	// keep the persisted level and let the CLI surface any objection.
+	if thinkingLevel != "" {
+		ok, err := agent.ValidateThinkingLevel(ctx, provider, entry.Path, model, thinkingLevel)
+		if err != nil {
+			taskLog.Warn("thinking_level: catalog lookup failed; passing through",
+				"provider", provider,
+				"model", model,
+				"thinking_level", thinkingLevel,
+				"error", err,
+			)
+		} else if !ok {
+			taskLog.Warn("thinking_level: not valid for this (provider, model); skipping injection",
+				"provider", provider,
+				"model", model,
+				"thinking_level", thinkingLevel,
+			)
+			thinkingLevel = ""
+		}
+	}
 	execOpts := agent.ExecOptions{
 		Cwd:                       env.WorkDir,
 		Model:                     model,