docs: drop redundant sustained scenario from single-client retry demo

docs/demos/retry.md

@@ -7,7 +7,7 @@ a dead backend can't be amplified.
 
 <div class="hw-demo" id="retry-demo"></div>
 
-<p>That was <b>one</b> client. The real danger of blind retries shows up at scale — when <b>many</b> clients retry the same outage at once.</p>
+<p>That was <b>one</b> client recovering from a blip. The real danger of blind retries shows up at <b>scale</b> — when many clients hit a real outage at once.</p>
 
 <div class="hw-demo" id="retry-herd"></div>
 
@@ -20,22 +20,8 @@ document.addEventListener('DOMContentLoaded', function () {
         ? { ok: false, ms: 0.05, label: 'blip' } : { ok: true, ms: 0.05 },
       chainB: { retry: { maxAttempts: 3, baseDelay: 0.1, maxDelay: 5.0 },
                 budget: { ttl: 10.0, minRetriesPerSec: 10.0, percentCanRetry: 0.2 } } },
-    { id: 'sustained', label: 'Sustained outage', dur: 12.5,
-      fault: (now) => (now >= 2.0 && now < 9.0)
-        ? { ok: false, ms: 0.05, label: 'DOWN' } : { ok: true, ms: 0.05 },
-      chainB: { retry: { maxAttempts: 3, baseDelay: 0.1, maxDelay: 5.0 },
-                budget: { ttl: 10.0, minRetriesPerSec: 10.0, percentCanRetry: 0.2 } } },
   ],
-  buildStops: (scenario) => scenario.id === 'sustained' ? [
-    { when: (s) => s.now >= 1.2, spot: ['ifA', 'ifB'], title: 'A backend blip appears',
-      body: 'Both clients hit the same transient errors. Watch how each responds.' },
-    { when: (s) => s.now >= 2.4, spot: ['ifB'], title: 'httpware retries the blip',
-      body: 'The plain client surfaces the error immediately. httpware retries with backoff — most of these recover on attempt 2 or 3, invisibly to the caller.' },
-    { when: (s) => s.mw.budgetExhausted, spot: ['ifB'], title: 'The budget refuses to amplify',
-      body: 'On a SUSTAINED outage, blind retries would multiply load. The budget is spent — httpware STOPS retrying and fails fast, protecting the dying backend instead of hammering it.' },
-    { when: (s) => s.now >= 10.0, spot: ['ifA', 'ifB'], title: 'Blip: recovered. Outage: contained',
-      body: 'Retry rescues transient errors without turning a real outage into a storm. That cap is the whole reason the budget exists.' },
-  ] : [
+  buildStops: () => [
     { when: (s) => s.now >= 1.2, spot: ['badWrapA', 'badWrapB'], title: 'A backend blip appears',
       body: 'Both clients are about to hit the same transient errors. Keep your eye on the ✗ failed counts — they start equal at zero.' },
     { when: (s) => s.now >= 2.4, spot: ['badWrapA', 'badWrapB'], title: 'Plain surfaces every error; httpware retries',
@@ -47,7 +33,7 @@ document.addEventListener('DOMContentLoaded', function () {
 
   HttpwareDemo.mountHerd('#retry-herd', {
     clients: 20,
-    intro: 'A real backend rarely dies cleanly — it <b>flaps</b>: fails, recovers, fails again. These strips show <b>backend call-rate over time</b> for twenty clients through three dips. Press play and watch the shape.',
+    intro: 'Retry rescues a transient blip (above) — but it can’t fix an <i>outage</i>: retried or not, the caller sees the same failures. There the danger isn’t caller failures, it’s <b>amplification</b>. A real backend rarely dies cleanly — it <b>flaps</b>: fails, recovers, fails again. These strips show <b>backend call-rate over time</b> for twenty clients through three dips. Press play and watch the shape.',
     scenario: { id: 'storm', dur: 12.5,
       fault: (now) => {
         const down = (now >= 2.0 && now < 4.0) || (now >= 5.5 && now < 7.5) || (now >= 9.0 && now < 11.0);

planning/changes/2026-07-19.03-drop-single-client-sustained-scenario.md

@@ -0,0 +1,44 @@
+---
+summary: Dropped the redundant "Sustained outage" scenario from the single-client retry demo (retry can't help the caller on a sustained outage, so its counters read ~equal and misled) and moved the myth-bust into the herd intro, which now owns the outage story with numbers that pop.
+---
+
+# Change: Drop the single-client retry demo's sustained-outage scenario
+
+**Lane:** lightweight — docs demo only, one file (`docs/demos/retry.md`), no capability contract moves.
+
+## Goal
+
+The single-client retry demo's "Sustained outage" scenario shows plain ✗82 vs
+httpware ✗81 — near-identical, because retry genuinely cannot rescue a caller
+from a *sustained* outage (the backend is down the whole time). That is correct
+model behavior, but it makes the scenario read as "no difference", against the
+suite's design where every scenario spotlights a number that pops. Its stop copy
+also overclaimed ("httpware STOPS retrying and **fails fast**") while the
+fast-failed counter stays 0 — a budget-exhausted request still hits the backend
+once and is counted as ✗, not a fast-fail.
+
+## Approach
+
+Remove the sustained scenario from the single-client demo, leaving only the
+"Brief blip" scenario, where retry's caller-visible win is self-evident (plain
+✗6 vs httpware ✗0). The sustained/amplification story now lives — with numbers
+that pop (naive ~18× vs httpware ~3×) — in the herd view directly below, added
+in `2026-07-19.02`. Preserve the "retry rescues blips, not outages" myth-bust as
+one line of the herd intro rather than a whole flat scenario, and align the
+bridging prose (the single-client demo now shows a blip, not an outage).
+
+`buildStops` loses its `scenario.id === 'sustained'` branch and becomes the
+single blip stop-list.
+
+## Files
+
+- `docs/demos/retry.md` — remove the `sustained` scenario + its stop branch;
+  simplify `buildStops`; add the myth-bust to the herd `intro`; retune the
+  bridging `<p>`.
+
+## Verification
+
+- [ ] `just docs-build --strict` clean; `just check-planning` OK.
+- [ ] jsdom harnesses green: `verify-demos.js` (retry single-client tour still
+      completes with the one blip scenario), `verify-herd.js`, `verify-real-page.js`.
+- [ ] `node --check docs/demos/engine.js` (unchanged, sanity).