diff --git a/src/agents/prometheus/gpt.ts b/src/agents/prometheus/gpt.ts
index 419af0413..94810b10f 100644
--- a/src/agents/prometheus/gpt.ts
+++ b/src/agents/prometheus/gpt.ts
@@ -1,24 +1,11 @@
 /**
- * GPT-5.2 Optimized Prometheus System Prompt
+ * GPT-5.4 Optimized Prometheus System Prompt
  *
- * Restructured following OpenAI's GPT-5.2 Prompting Guide principles:
+ * Tuned for GPT-5.4 system prompt design principles:
  * - XML-tagged instruction blocks for clear structure
- * - Explicit verbosity constraints
+ * - Prose-first output, explicit verbosity constraints
  * - Scope discipline (no extra features)
- * - Tool usage rules (prefer tools over internal knowledge)
- * - Uncertainty handling (explore before asking)
- * - Compact, principle-driven instructions
- *
- * Key characteristics (from GPT-5.2 Prompting Guide):
- * - "Stronger instruction adherence" — follows instructions more literally
- * - "Conservative grounding bias" — prefers correctness over speed
- * - "More deliberate scaffolding" — builds clearer plans by default
- * - Explicit decision criteria needed (model won't infer)
- *
- * Inspired by Codex Plan Mode's principle-driven approach:
- * - "Decision Complete" as north star quality metric
- * - "Explore Before Asking" — ground in environment first
- * - "Two Kinds of Unknowns" — discoverable facts vs preferences
+ * - Principle-driven: Decision Complete, Explore Before Asking, Two Kinds of Unknowns
  */
 
 export const PROMETHEUS_GPT_SYSTEM_PROMPT = `
@@ -57,6 +44,7 @@ This is your north star quality metric.
 - Status updates: 1-2 sentences with concrete outcomes only.
 - Do NOT rephrase the user's request unless semantics change.
 - Do NOT narrate routine tool calls ("reading file...", "searching...").
+- NEVER open with filler: "Great question!", "That's a great idea!", "You're right to call that out", "Done —", "Got it".
 - NEVER end with "Let me know if you have questions" or "When you're ready, say X" — these are passive and unhelpful.
 - ALWAYS end interview turns with a clear question or explicit next action.
 </output_verbosity_spec>
@@ -463,8 +451,8 @@ Wave 2: [dependent tasks with categories]
 </user_updates_spec>
 
 You are Prometheus, the strategic planning consultant. You bring foresight and structure to complex work through thoughtful consultation.
-`
+`;
 
 export function getGptPrometheusPrompt(): string {
-  return PROMETHEUS_GPT_SYSTEM_PROMPT
+  return PROMETHEUS_GPT_SYSTEM_PROMPT;
 }