diff --git a/swarmmetrics.py b/swarmmetrics.py
index 7a5173f..45a76fe 100644
--- a/swarmmetrics.py
+++ b/swarmmetrics.py
@@ -223,7 +223,8 @@ def score_channels(messages: list[dict], gini_broadcast_threshold: float = 0.6)
 def score_echo(messages: list[dict], concept_window_seconds: float = 604800,
                use_idf: bool = True, snapshot_idf: bool = False,
                idf_window_seconds: float = 0,
-               idf_decay_halflife: float = 0) -> dict:
+               idf_decay_halflife: float = 0,
+               jitter_seconds: float = 0) -> dict:
     """
     Echo coefficient: measures concept diffusion from nodes that
     don't reply but whose concepts appear downstream.
@@ -252,7 +253,23 @@ def score_echo(messages: list[dict], concept_window_seconds: float = 604800,
     decays as exp(-λ·Δt) where λ = ln(2)/halflife. Fixes the boundary
     discontinuity of hard windows. Suggested by Eliza-Gemma (Colony,
     2026-07-28). Overrides idf_window_seconds if both are set.
+
+    When jitter_seconds > 0, adds uniform random noise ±jitter_seconds
+    to all timestamps before scoring. Defense against injection attacks:
+    attacker's precise timing is washed out by random perturbation.
+    Binary phase transition at Δt=0 becomes probabilistic over N messages.
+    Discovered via injection taxonomy (Dispatch, 2026-07-28): targeted
+    injection achieves -100% kill by pre-empting with 1s precision;
+    ±10s jitter recovers 96% of baseline echo.
     """
+    import random as _rng
+    # Apply jitter defense if requested
+    if jitter_seconds > 0:
+        messages = [
+            {**m, "timestamp": m.get("timestamp", 0) + _rng.uniform(-jitter_seconds, jitter_seconds)}
+            for m in messages
+        ]
+
     # Sort messages by time for temporal IDF snapshots
     sorted_msgs = sorted(messages, key=lambda m: m.get("timestamp", 0))