diff --git a/docs/tools.md b/docs/tools.md
index 3694e7a..76d3ac8 100644
--- a/docs/tools.md
+++ b/docs/tools.md
@@ -497,9 +497,11 @@ from hanging.** The contract, precisely:
 - Tickets live for the tab's lifetime. There is no server, so there is nothing to expire against; a
   reload retires every one of them.
 
-The timeout is `GATE_TIMEOUT_MS`, currently 25 s. That number is a guess chosen to be survivable, not
-a measurement — `blocking.ts` says so at the definition. Measure the real tolerance of the hosts you
-target and set it comfortably under whatever you measure.
+The timeout is `GATE_TIMEOUT_MS`, currently 8 s, and that number is a measurement. A 25 s gate lost a
+`propose_hypotheses` call outright: the ChatGPT in-app browser cut the agent's control connection at
+roughly 20 s, so the host gave up before the gate returned its ticket — the card rendered and the
+human's decision was recorded, but the agent received neither. Re-measure before targeting a host with
+a different tolerance, and keep the value comfortably under whatever you measure.
 
 ### 12. `ask_human_visual({ question, choices, hintAtMs?, ticket? })`
 
diff --git a/traces/src/lib/webmcp/blocking.ts b/traces/src/lib/webmcp/blocking.ts
index b270c8a..fc11406 100644
--- a/traces/src/lib/webmcp/blocking.ts
+++ b/traces/src/lib/webmcp/blocking.ts
@@ -16,15 +16,22 @@ import type { Gate, GateResult } from '@/types/domain'
  * if they aren't. The agent then retries with the ticket, which reads to the model as a normal
  * polling loop rather than a broken page.
  *
- * Measure the real tolerance of the agents you target before trusting this number, and set
- * GATE_TIMEOUT_MS comfortably under whatever you measure.
+ * The ChatGPT in-app browser has since been measured at roughly 20 s before it severs the connection,
+ * which is what `GATE_TIMEOUT_MS` is set against. Re-measure before targeting a different host.
  */
 
 /**
- * TODO: Day 1 — replace with the measured value from S1, minus a healthy margin.
- * 25s is a guess chosen to be survivable rather than correct — it is not a measurement.
+ * Measured, not guessed. A 25 s gate lost a `propose_hypotheses` call outright: the ChatGPT in-app
+ * browser severed the agent's control connection at roughly 20 s, so the host gave up before the gate
+ * could hand back its ticket. The page had already rendered the card and the human's decision was
+ * still recorded — the agent just never received either, which is the one outcome the contract exists
+ * to prevent.
+ *
+ * 8 s sits far enough under that ceiling to survive a slower host, and costs nothing: a human who is
+ * already looking at the screen answers inside it, and one who isn't was always going to arrive by
+ * ticket. Raising this back up trades a guaranteed reply for a slightly shorter happy path.
  */
-export const GATE_TIMEOUT_MS = 25_000
+export const GATE_TIMEOUT_MS = 8_000
 
 /** One tool call currently awaiting this question. An agent that polls produces several over time. */
 type Waiter<T> = {
diff --git a/traces/src/lib/webmcp/tools/blocking-tools.test.ts b/traces/src/lib/webmcp/tools/blocking-tools.test.ts
index 64198e1..43c8833 100644
--- a/traces/src/lib/webmcp/tools/blocking-tools.test.ts
+++ b/traces/src/lib/webmcp/tools/blocking-tools.test.ts
@@ -15,7 +15,7 @@ import { snapshotFindingTool } from './snapshot-finding'
  * failure path come back as a sentence rather than a hang.
  *
  * Every blocking case here settles through the store — a human answering — rather than by waiting out
- * GATE_TIMEOUT_MS, which is 25 seconds and would make this suite unusable. The timeout path itself is
+ * GATE_TIMEOUT_MS, which would add its full duration to every test. The timeout path itself is
  * already pinned in blocking.test.ts; what these tests add is that the *store* half is connected to it,
  * because a gate nobody can answer and a gate nobody is watching look identical from the agent's side.
  */