diff --git a/netlify/edge-functions/agent-proxy.ts b/netlify/edge-functions/agent-proxy.ts
index 2974ba6..7572f32 100644
--- a/netlify/edge-functions/agent-proxy.ts
+++ b/netlify/edge-functions/agent-proxy.ts
@@ -59,13 +59,19 @@ const ANTHROPIC_VERSION = '2023-06-01'
 const ANTHROPIC_API_BASE = 'https://api.anthropic.com'
 
 // Downstream keep-alive cadence. The browser's fetch reader appears
-// stuck if no bytes flow for too long.
-const HEARTBEAT_MS = 10_000
+// stuck if no bytes flow for too long. We keep this tighter than the
+// segment budget so the connection stays warm even during long
+// model-thinking gaps with no agent events.
+const HEARTBEAT_MS = 5_000
 
-// Close the current response just before Netlify's empirical ~60 s
-// streaming cap. Leaves a few seconds for a final `segment_end` write
-// + `controller.close()` to flush cleanly.
-const SEGMENT_BUDGET_MS = 54_000
+// Close the current response well before Netlify's empirical streaming
+// cap. We've observed responses cut anywhere between ~49 s and ~60 s,
+// so a 54 s budget is too aggressive — sometimes the platform pulls
+// the rug out before our final `segment_end` write + `controller.close()`
+// can flush. 40 s gives ~10 s of headroom on the low end of the
+// observed range while still amortising session setup (~1 segment per
+// ~40 s of brief) across a typical 3-5 min brief.
+const SEGMENT_BUDGET_MS = 40_000
 
 // Total wall-clock allowance across ALL segments for a single user
 // brief. Past this we emit a final `error` line and stop reopening.
@@ -660,13 +666,12 @@ Please follow your instructions to produce the funding outlook brief.`
           }
 
           if (done || segmenting) {
-            // Drain the live-stream body we opened above so we don't
-            // leak the connection.
-            try {
-              await upstream.cancel()
-            } catch {
-              /* ignore */
-            }
+            // The upstream fetch is already cleaned up by
+            // `segmentAbort.abort()` (or will be by the runtime once
+            // we drop our reference). Don't `await upstream.cancel()`
+            // here — on an already-aborted body that call can hang
+            // on Deno Edge, which would prevent us from writing the
+            // final `segment_end` line.
             break
           }