diff --git a/server/internal/daemon/daemon.go b/server/internal/daemon/daemon.go
index 010bd3027..5b0e79959 100644
--- a/server/internal/daemon/daemon.go
+++ b/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,