Twelve requests, twelve pages.

@title Plotline onboarding: six directions
@subtitle Six first-run screens that differ in layout, tone and density, each with the tradeoff it makes
@author Claude, Design exploration
@date 2026-10-19
@width wide

Plotline is a project tracker for small agencies. The first-run screen appears right after sign-up and has one job: get a new user to their first real project. The six directions below are deliberately far apart. Each card states the tradeoff it is making, then its layout, tone and density, then a wireframe.

! Seconds, field and screen counts are design-heuristic estimates for comparison, not measured results. Test the top two with five users each before committing.

## The six directions

cards

### 1. One Pass
**Tradeoff: fastest to finish and easiest to build, but it looks like paperwork.**
- Layout: one column, every field visible at once
- Tone: terse and neutral ("Set up Plotline")
- Density: high, 6 inputs on one screen
```
+------------------------------+
| Set up Plotline              |
| Name      [______________]   |
| Role      [______________]   |
| Team size [______]           |
| Work email [_____________]   |
| Found us via [___________]   |
| [x] I agree     [ Create ]   |
+------------------------------+
```

### 2. Guided Wizard
**Tradeoff: collects clean profile data and feels supportive, but it delays the product by four screens.**
- Layout: centered card, stepper at the top, one decision per step
- Tone: warm and conversational ("What kind of work do you do?")
- Density: low, about 2 inputs per step
```
+------------------------------+
|  (1)--(2)--(3)--(4)          |
|                              |
|  What kind of work do you    |
|  do?                         |
|    ( ) Agency  ( ) In-house  |
|                              |
|  Back                [ Next ]|
+------------------------------+
```

### 3. Checklist Dashboard
**Tradeoff: no gate before the app, but a user can ignore the checklist and never reach value.**
- Layout: the real app shell with a pinned progress panel
- Tone: task-oriented ("2 of 5 done")
- Density: medium, 5 actions visible with progress
```
+------------------------------+
| Welcome, Sam.    2 of 5 done |
| [########-----------]  40%   |
| [x] Create your first project|
| [x] Add a client             |
| [ ] Invite a teammate        |
| [ ] Connect your calendar    |
| [ ] Send a first update      |
+------------------------------+
```

### 4. Personalization Quiz
**Tradeoff: strongest tailoring and a playful first impression, but six screens before any product.**
- Layout: one big question per screen, large tap targets, full bleed color
- Tone: playful and chatty ("How do you run your Monday?")
- Density: very low, 1 question and 2 to 4 answers per screen
```
+------------------------------+
|           3 / 6              |
|   How do you run your        |
|   Monday?                    |
|  +-----------+ +-----------+ |
|  |  Lists    | |  Boards   | |
|  +-----------+ +-----------+ |
+------------------------------+
```

### 5. Template First
**Tradeoff: near-instant time to value, but a user with an unusual workflow sees nothing that fits.**
- Layout: gallery of 6 starter projects, a single click starts one
- Tone: minimal, almost no copy
- Density: medium, 6 visual tiles and one escape hatch
```
+------------------------------+
| Start from a template        |
| +-------+ +-------+ +------+ |
| | Brief | |Launch | | Audit| |
| +-------+ +-------+ +------+ |
| +-------+ +-------+ +------+ |
| |Retain | |Pitch  | | Event| |
| +-------+ +-------+ +------+ |
|          [ Start blank ]     |
+------------------------------+
```

### 6. Sandbox Tour
**Tradeoff: teaches by doing and needs no setup, but it is the most work to build and keep current.**
- Layout: a populated sample project with coach marks over the real UI
- Tone: instructional ("This is a task. Drag it to Done.")
- Density: high, a full board plus one tooltip at a time
```
+------------------------------+
| Sample: Acme Rebrand         |
| +-----------+                |
| | To do|Done|  (1) This is a|
| | [ ] [ ]   |  task. Drag it|
| +-----------+  to Done.     |
| [Skip tour]  [Use my own 1/5]|
+------------------------------+
```

## Side by side on the three axes

table = direction,layout,tone,density,best when; **1. One Pass**,single column,terse,high,"users arrive with intent, such as invited teammates"; **2. Guided Wizard**,stepper card,warm,low,"you need profile data to route the user"; **3. Checklist Dashboard**,app shell plus panel,task-oriented,medium,"the product explains itself in seconds"; **4. Personalization Quiz**,full-bleed questions,playful,very low,"the audience is mixed and engagement is the risk"; **5. Template First**,tile gallery,minimal,medium,"common workflows cover most of your users"; **6. Sandbox Tour**,coach marks over sample data,instructional,high,"the product is unusual and needs demonstrating"

## What each costs the user

Estimated effort before the user reaches their first project.

data est = direction,seconds,fields,screens; "1 One Pass",75,6,1; "2 Guided Wizard",140,7,4; "3 Checklist",20,2,1; "4 Quiz",95,6,6; "5 Template First",30,1,2; "6 Sandbox Tour",45,0,5

chart hbar est y=seconds unit=s title="Estimated seconds to first project" focus="3 Checklist"

table est heat title="Effort estimates (lower is lighter)"

grid 2
chart bar est y=fields,screens title="Fields and screens per direction"
! Two directions look similar on speed and differ on cost. Checklist and Template First both finish under 30 seconds, but Template First asks for a choice up front and Checklist defers all setup. Pick on which failure you can live with: a wrong template pick or an ignored checklist.

## How to choose

One path through the questions below lands on each direction.

diagram pick dir=TB title="Which direction fits"
pick: d1 "Need profile data on day one?" decision focus
pick: d2 "Is the product obvious in 30 seconds?" decision
pick: d3 "Do users arrive with intent?" decision
pick: d4 "Do reusable starting points exist?" decision
pick: d5 "Is personalization the hook?" decision
pick: one "1. One Pass" svc
pick: wiz "2. Guided Wizard" svc
pick: chk "3. Checklist" svc
pick: quiz "4. Quiz" svc
pick: tpl "5. Template First" svc
pick: sbx "6. Sandbox Tour" svc
pick: d1 -> d3 : yes
pick: d1 -> d2 : no
pick: d3 -> one : yes
pick: d3 -> d5 : no
pick: d5 -> quiz : yes
pick: d5 -> wiz : no
pick: d2 -> d4 : yes
pick: d2 -> sbx : no
pick: d4 -> tpl : yes
pick: d4 -> chk : no

## Recommendation

- Ship **3. Checklist Dashboard** as the default: it never blocks the user and costs the least to build.
- Prototype **5. Template First** as the challenger, since it has the shortest path to a populated first project.
- Keep **2. Guided Wizard** only if sales needs team size and role on day one.

!! Directions 4 and 6 carry the highest build and maintenance cost. Choose them only if user testing shows the simpler options fail to activate people.

---
[Back to the examples](/gallery/)

@title Search-as-you-type: implementation plan
@subtitle Debounced input with request cancellation for the product search box in the React app
@author Claude, Frontend platform
@date 2026-10-19
@width wide

## TL;DR

Today the search box fires one request per keystroke and shows whichever response lands last. This plan adds a 250 ms debounce and cancels the superseded request with `AbortController`, so results always match what is in the box.

kpi Requests per search | 3 | -73% vs. 11 today | good
kpi Debounce | 250 ms | trial range 150 to 400 ms | neutral
kpi Estimate | 8 days | 2 engineers | neutral
kpi Files touched | 7 | 3 new | neutral

- **In scope:** the header search box, the `useSearch` hook, the fetch client, tests, a feature flag.
- **Out of scope:** server-side ranking, search history, keyboard navigation of results.
- **Done means:** typing "react hooks" never shows results for "react ho", and the Network tab shows aborted requests rather than parallel ones.

## What the user sees

Four states of the search box. The key rule: old results stay on screen while a new request is loading, so the list never flashes empty.

grid 2 count=4
```
IDLE (fewer than 2 characters)
+-----------------------------+
| (search) Search products... |
+-----------------------------+
 Type 2 or more characters
```
```
LOADING (old results stay visible)
+-----------------------------+
| (search) react ho      (...)|
+-----------------------------+
 React Hooks Handbook   (dim)
 React Hooks in Depth   (dim)
```
```
RESULTS
+-----------------------------+
| (search) react hooks     (x)|
+-----------------------------+
 React Hooks Handbook
 React Hooks in Depth
 Hooks Cheat Sheet        3 hits
```
```
EMPTY and ERROR
+-----------------------------+
| (search) zzzq            (x)|
+-----------------------------+
 No results for "zzzq"

 Error: Search failed (503)
 [ Retry ]
```

## How the data flows

Everything between the keystroke and the screen runs in the browser except one request. The hook `useSearch` is the only place that owns an `AbortController`.

diagram flow dir=LR title="Keystroke to results"
flow: user "User" user
flow: box "SearchBox" fn "controlled input"
flow: deb "useDebouncedValue" fn "250 ms idle"
flow: hook "useSearch" fn "owns AbortController" focus
flow: cache "Query cache" cache "Map, 60 s TTL"
flow: list "ResultsList" fn
flow: api "GET /api/search" svc "existing endpoint"
flow: group app "React app (browser)" box, deb, hook, cache, list
flow: user -> box : keystrokes
flow: box -> deb : raw text
flow: deb -> hook : settled query
flow: hook -> cache : lookup
flow: cache --> list : hit
flow: hook -> api : fetch + signal
flow: api --> hook : JSON
flow: hook -> list : items, status

### What happens when two queries overlap

The case this feature exists for: the user keeps typing while request A is still in flight.

diagram race sequence title="Typing past an in-flight request"
race: user "User" user
race: box "SearchBox" fn
race: hook "useSearch" fn
race: api "Search API" svc
race: user -> box : types re
race: box -> hook : query re after 250 ms idle
race: hook -> api : GET q=re (request A)
race: user -> box : types a
race: box -> hook : query rea after 250 ms idle
race: note hook : effect cleanup calls A.abort()
race: hook --> api : abort A
race: hook -> api : GET q=rea (request B)
race: opt "A was already in flight"
race: api --> hook : A rejects with AbortError
race: note hook : ignored, state untouched
race: end
race: api --> hook : B returns 200 with items
race: hook --> box : status ok, items from B

## Decisions worth a look

### Debounce delay

data deb = delay,requests,added wait ms; "0 ms",11,0; "150 ms",6,150; "250 ms",3,250; "400 ms",2,400

Requests fired while typing "react hooks" in a recorded burst-typing session.

chart bar deb x=delay y=requests title="Requests per search by debounce delay" focus="250 ms"

!! The delay is the latency floor. 250 ms is the usual point where requests drop sharply without the box feeling laggy. Make it a constant and revisit after a week of real traffic.

### Other choices

table = decision,chosen,rejected,why; Cancellation,`AbortController` per effect,"ignore-stale flag only","Cancels the network request as well as the update"; Debounce,"hook on the value","debounced callback","Works with React 18 Strict Mode double effects"; Cache,"in-memory `Map`, 60 s","SWR or React Query","No new dependency for one box"; Min length,2 characters,1 character,"One letter matches most of the catalog"

## Code to review

### 1. The debounce hook

Debounce the value, not the handler. The cleanup clears the timer on every change, which is the whole trick.

```ts
// src/hooks/useDebouncedValue.ts
import { useEffect, useState } from 'react';

export function useDebouncedValue<T>(value: T, delayMs = 250): T {
  const [debounced, setDebounced] = useState(value);

  useEffect(() => {
    const id = setTimeout(() => setDebounced(value), delayMs);
    return () => clearTimeout(id);
  }, [value, delayMs]);

  return debounced;
}
```

### 2. The search hook with cancellation

The cleanup function aborts the previous request. The `AbortError` guard stops a cancelled request from being reported as a failure.

```ts
// src/hooks/useSearch.ts
const MIN_CHARS = 2;

export function useSearch(query: string): SearchState {
  const [state, setState] = useState<SearchState>({ status: 'idle', items: [] });

  useEffect(() => {
    const q = query.trim();
    if (q.length < MIN_CHARS) {
      setState({ status: 'idle', items: [] });
      return undefined;
    }

    const controller = new AbortController();
    setState((s) => ({ ...s, status: 'loading' })); // keep old items on screen

    searchApi(q, controller.signal)
      .then((items) =>
        setState({ status: items.length ? 'ok' : 'empty', items }),
      )
      .catch((err) => {
        if (err.name === 'AbortError') return; // superseded, not a failure
        setState({ status: 'error', items: [], error: err.message });
      });

    return () => controller.abort();
  }, [query]);

  return state;
}
```

### 3. The fetch client

```ts
// src/api/search.ts
export async function searchApi(q: string, signal: AbortSignal): Promise<Item[]> {
  const res = await fetch(`/api/search?q=${encodeURIComponent(q)}`, { signal });
  if (!res.ok) throw new Error(`Search failed (${res.status})`);
  return (await res.json()).items;
}
```

### 4. The component

```tsx
// src/components/SearchBox.tsx
export function SearchBox() {
  const [text, setText] = useState('');
  const debounced = useDebouncedValue(text, 250);
  const { status, items, error } = useSearch(debounced);

  return (
    <div role="search">
      <input
        value={text}
        onChange={(e) => setText(e.target.value)}
        aria-busy={status === 'loading'}
        aria-controls="search-results"
      />
      <ResultsList id="search-results" status={status} items={items} error={error} />
    </div>
  );
}
```

### 5. The test that proves cancellation

```ts
// src/hooks/useSearch.test.ts
it('aborts the previous request when the query changes', async () => {
  const signals: AbortSignal[] = [];
  vi.spyOn(api, 'searchApi').mockImplementation((_q, signal) => {
    signals.push(signal);
    return new Promise(() => {}); // never resolves
  });

  const { rerender } = renderHook(({ q }) => useSearch(q), {
    initialProps: { q: 're' },
  });
  rerender({ q: 'rea' });

  expect(signals).toHaveLength(2);
  expect(signals[0].aborted).toBe(true);
  expect(signals[1].aborted).toBe(false);
});
```

## State machine

table = state,entered when,shows,leaves when; **idle**,"fewer than 2 characters",hint text,"2 or more characters settle"; **loading**,"a request starts",previous items dimmed,"response, error or abort"; **ok**,"1 or more items return","result list","query changes"; **empty**,"0 items return","No results message","query changes"; **error**,"non-2xx or network failure","message and Retry","query changes or Retry"

## Files

table = file,change,status; `src/hooks/useDebouncedValue.ts`,new,Ready; `src/hooks/useSearch.ts`,new,Ready; `src/api/search.ts`,"accept an `AbortSignal`",Ready; `src/components/SearchBox.tsx`,"wire both hooks",In progress; `src/components/ResultsList.tsx`,"add loading and error states",In progress; `src/hooks/useSearch.test.ts`,new,Ready; `src/flags.ts`,"add `searchDebounce` flag",Ready

## Risks and edge cases

!! **Stale response overwrites fresh one.** If the `AbortError` guard is removed, a late response from request A can replace results for B. The cancellation test above protects this.

!! **IME composition.** While a user composes Japanese or Chinese text, intermediate input should not search. Skip updates between `compositionstart` and `compositionend`.

! **Strict Mode runs effects twice in development.** The first request is aborted by the cleanup and re-issued. This is expected and harmless.

! **Aborting does not stop server work.** The browser drops the connection, but the server may still finish the query. Confirm the API cancels on client disconnect before launch.

## Test plan

table = case,how,expected; Overlapping queries,"unit test, fake timers","earlier signal aborted, later one live"; Late A after B,"mock A to resolve after B","results show B"; Slow network,"throttle to 3G in devtools","old items stay visible while loading"; Empty and error,"mock 200 with [] and 503","empty message, error with Retry"; Rapid backspace,"hold Backspace to empty","returns to idle, no request"; Strict Mode,"mount in dev","at most one live request per query"

## Schedule

data plan = task,start,end; "Hooks and unit tests",2026-10-20,2026-10-22; "API signal support",2026-10-21,2026-10-23; "Component and states",2026-10-22,2026-10-26; "Accessibility and IME pass",2026-10-26,2026-10-28; "Flagged rollout",2026-10-28,2026-10-30

chart range plan from=start to=end target="2026-10-30 release" title="Eight working days"

## Rollout

step Merge behind the `searchDebounce` flag | 2026-10-26 | Priya
step Enable for internal staff | 2026-10-28 | Priya
step Enable for 10% of traffic and watch request volume | 2026-10-29 | Marcus
step Full rollout, remove the flag next sprint | 2026-10-30 | Marcus

## Open questions

- [ ] Does `/api/search` cancel work when the client disconnects?
- [ ] Should the 60 s cache survive route changes, or reset on navigation?
- [ ] Is 2 characters the right minimum for non-Latin scripts?

---
[Back to the examples](/gallery/)

@title PR 2841: backpressure for CSV and NDJSON export
@subtitle A review guide that explains the streaming logic first, then walks the diff with findings under each hunk
@author Claude, Reviewer
@date 2026-10-19
@width wide

## Verdict

!!! **Request changes.** The backpressure logic is correct and well tested, but one path leaks a database connection: if the client disconnects while the export is paused, nothing resumes or closes the cursor.

kpi Blocking | 1 | fix before merge | bad
kpi Nits | 3 | optional | neutral
kpi Nice | 3 | worth keeping | good

The PR touches 2 files, `src/export/stream.js` (+15 -4) and `test/export/stream.test.js` (+21), about 40 changed lines.

## Backpressure in one minute

You asked for focus on the streaming logic, so here is the model before the diff.

A fast producer (the database cursor) can emit rows faster than a slow consumer (the HTTP response to a client on a poor connection) can send them. Node does not stop the producer on its own when you use `on('data')`. Unsent rows pile up in the response's memory buffer. For a 2 GB export that buffer grows until the process is killed.

The protocol has three parts.

1. `res.write(chunk)` returns `true` while the buffer has room and `false` once it passes its high-water mark (16 KiB by default).
2. On `false`, the producer must stop: call `cursor.pause()`.
3. When the buffer empties, `res` emits `'drain'`. The producer resumes: `cursor.resume()`.

diagram bp dir=LR title="The pause and resume loop"
bp: db "Cursor" db "produces rows" focus
bp: app "streamExport" fn "the code in this PR"
bp: res "HTTP response" svc "buffer, 16 KiB mark"
bp: client "Client" user "slow link"
bp: db -> app : data row
bp: app -> res : write(row)
bp: res -> client : bytes
bp: res --> app : false means full
bp: app --> db : pause()
bp: res --> app : drain event
bp: app --> db : resume()

The same loop as a timeline of one saturation cycle.

diagram cycle sequence title="One pause and resume cycle"
cycle: db "Cursor" db
cycle: app "streamExport" fn
cycle: res "HTTP response" svc
cycle: db -> app : data row
cycle: app -> res : write(row)
cycle: res --> app : true
cycle: note res : client is slow, buffer fills
cycle: db -> app : data row
cycle: app -> res : write(row)
cycle: res --> app : false
cycle: app -> db : pause()
cycle: note res : buffer drains to the client
cycle: res --> app : drain
cycle: app -> db : resume()

table = term,meaning; `write()` returns `false`,"the buffer passed the high-water mark; stop sending"; `highWaterMark`,"the buffer size that triggers `false`; 16 KiB for a response by default"; `'drain'`,"the buffer is empty again; safe to send"; `pause()` and `resume()`,"stop and restart `'data'` events on the cursor"

### Why the PR was needed

The benchmark in the PR description exports a 2 GB table to a client throttled to 5 Mbps. Memory before the fix grows without limit; after it stays flat.

data mem = minute,before,after; m0,120,118; m1,210,126; m2,340,131; m3,480,129; m4,610,133; m5,760,130; m6,890,132; m7,1010,131; m8,1130,134

chart line mem x=minute y=before,after unit=MB target="512 pod limit" title="Process memory during a 2 GB export" focus=after

## The diff, annotated

Each hunk is followed by the findings that apply to it. Severity is marked by tag and callout level: **BLOCKING** is a red alert, **NIT** is a warning, **NICE** is a note.

### src/export/stream.js

Before, every row was written and the return value ignored. After, the function pauses on `false` and resumes on `'drain'`. Read the three hunks in order.

#### Hunk 1: the signature and the flag

```diff
@@ -1,10 +1,21 @@
 'use strict';

-function streamExport(cursor, res) {
-  cursor.on('data', (row) => {
-    res.write(JSON.stringify(row) + '\n');
-  });
+function streamExport(cursor, res, { highWaterMark = 16 * 1024 } = {}) {
+  let paused = false;
+
```

!! **NIT, line 3.** `highWaterMark` is accepted but never used. The buffer threshold belongs to `res`, so this option cannot change it. Remove it, or pass it where the response is created.

!! **NIT, line 4.** `paused` reads like `cursor.isPaused()` but means "waiting for drain". Rename it `waitingForDrain` so the next reader does not swap them.

#### Hunk 2: the pause and resume

```diff
@@ -5,3 +6,10 @@ function streamExport(cursor, res, { highWaterMark = 16 * 1024 } = {}) {
+  cursor.on('data', (row) => {
+    const ok = res.write(JSON.stringify(row) + '\n');
+    if (ok || paused) return;
+    paused = true;
+    cursor.pause();
+    res.once('drain', () => {
+      paused = false;
+      cursor.resume();
+    });
+  });
```

! **NICE, line 7.** Using the return value of `write()` as the signal is exactly right. The guard `if (ok || paused) return` also prevents stacking several `'drain'` listeners when more rows arrive after the first `false`.

! **NICE, lines 11 to 14.** `once('drain')` removes itself after firing. No manual listener cleanup is needed in the normal path.

#### Hunk 3: end and error

```diff
@@ -7,2 +17,4 @@ function streamExport(cursor, res, { highWaterMark = 16 * 1024 } = {}) {
   cursor.on('end', () => res.end());
-}
+  cursor.on('error', (err) => res.destroy(err));
+}
```

!!! **BLOCKING, lines 17 to 18.** There is no handler for the client going away. If the client disconnects while `paused` is true, `res` emits `'close'` and never `'drain'`. The `drain` listener never fires, the cursor stays paused forever and the database connection is held until the server times out. With mobile clients on 2 GB exports this exhausts the pool. Destroy the cursor when the response closes.

```js
cursor.on('end', () => res.end());
cursor.on('error', (err) => res.destroy(err));
res.once('close', () => cursor.destroy()); // client left: release the connection
```

! **NICE, line 18.** Destroying the response on a cursor error is better than ending it. The client sees an aborted transfer instead of a file that looks complete but is truncated.

### test/export/stream.test.js

#### Hunk 4: the slow-consumer test

```diff
@@ -0,0 +1,21 @@
+const test = require('node:test');
+const assert = require('node:assert');
+const { once } = require('node:events');
+const { Readable, Writable } = require('node:stream');
+const { streamExport } = require('../../src/export/stream');
+
+test('keeps the response buffer bounded for a slow consumer', async () => {
+  const cursor = Readable.from(Array.from({ length: 1000 }, (_, i) => ({ i })));
+  let peak = 0;
+  const res = new Writable({
+    highWaterMark: 256,
+    write(_chunk, _enc, cb) { setTimeout(cb, 1); },
+  });
+  const timer = setInterval(() => {
+    peak = Math.max(peak, res.writableLength);
+  }, 5);
+  streamExport(cursor, res);
+  await once(res, 'finish');
+  clearInterval(timer);
+  assert.ok(peak < 1024, `peak buffer ${peak} B`);
+});
```

! **NICE, lines 9 to 12.** The test uses a deliberately slow `Writable`. That is the only reliable way to exercise `'drain'` without a real network.

!! **NIT, lines 13 to 15.** Sampling `writableLength` every 5 ms can miss the real peak and pass for the wrong reason. Track it inside `write()` instead.

```js
write(chunk, _enc, cb) {
  peak = Math.max(peak, this.writableLength);
  setTimeout(cb, 1);
},
```

!! **No test covers the missing path.** Add a case where `res.destroy()` is called mid-export and assert that the cursor is destroyed. It fails today and passes with the blocking fix.

## All findings

table = id,severity,where,summary,action; B1,**blocking**,"stream.js 17 to 18","cursor never released when client disconnects while paused","add `res.once('close', ...)` and a test"; N1,**nit**,"stream.js 3","`highWaterMark` option is unused","remove it"; N2,**nit**,"stream.js 4","`paused` name hides its meaning","rename to `waitingForDrain`"; N3,**nit**,"test 13 to 15","interval sampling can miss the peak","record inside `write()`"; Y1,**nice**,"stream.js 7","uses the `write()` return value","keep"; Y2,**nice**,"stream.js 11 to 14","`once('drain')` self-cleans","keep"; Y3,**nice**,"test 9 to 12","slow `Writable` exercises drain","keep"

## Before you approve

- [ ] B1 fixed and the disconnect test added
- [ ] Run the new test locally and confirm it passes
- [ ] Confirm the DB pool size is shown in the connection metrics after a cancelled export
- [ ] Check that `highWaterMark` has no other caller before removing it

step Reproduce B1 with curl --limit-rate 1k and Ctrl-C | now | Reviewer
step Author applies the close handler and test | 2026-10-20 | PR author
step Re-review the delta only | 2026-10-21 | Reviewer

---
[Back to the examples](/gallery/)

@title Northwind design tokens v0.3
@subtitle Color, type, spacing and button tokens for review
@author Design systems team
@date 2026-10-19
@width wide

! Review notes: values below are the proposed tokens. Swatches and buttons cannot be painted on this page, so each color is given by hex with its measured contrast, and each button by its exact token recipe.

kpi Colors | 15 | 4 families | neutral
kpi Type sizes | 8 | ratio 1.25 | neutral
kpi Spacing steps | 8 | 4 px base | neutral
kpi Button variants | 4 | 3 sizes | neutral

## Color

### Brand and neutral

data colors = token,hex,role,on white,on neutral-900; brand-600,#5B3FD9,primary action and links,6.8,2.6; brand-500,#6E56E8,hover and focus ring,5.1,3.4; brand-100,#ECE8FD,selected row and tint,1.2,14.6; neutral-900,#14131A,body text and dark surface,17.9,1.0; neutral-700,#3B3947,secondary text,10.8,1.7; neutral-500,#6B6879,placeholder and icons,5.4,3.3; neutral-200,#DAD8E2,borders and dividers,1.4,12.7; neutral-50,#F6F5F9,page background,1.1,16.3
table colors

### Status

data status = token,hex,use,on white; success-600,#1F8F5F,confirmations and paid,4.6; warning-600,#B7791F,pending and caution,4.0; danger-600,#C93B3B,errors and destructive,5.0; info-600,#2563C9,neutral notices,5.7
table status

### Contrast against white

Text must reach 4.5:1 for AA. The dashed line is the pass mark.

data contrast = token,ratio; neutral-900,17.9; neutral-700,10.8; brand-600,6.8; info-600,5.7; neutral-500,5.4; brand-500,5.1; danger-600,5.0; success-600,4.6; warning-600,4.0
chart hbar contrast unit=:1 target="4.5 AA" labels title="Contrast ratio on white"

!! warning-600 is 4.0:1 on white and fails AA for body text. Allowed for icons and large text only, or darken to #9A6516 (5.3:1).

## Type scale

Base 16 px, scale ratio 1.25 rounded to whole pixels. Family is Inter for UI and JetBrains Mono for code.

data type = token,size px,line height px,weight,use; text-xs,12,16,500,captions and legal; text-sm,14,20,400,table cells and helper text; text-base,16,24,400,body; text-lg,18,28,500,lead paragraph; text-xl,22,30,600,card titles; text-2xl,28,36,600,section headings; text-3xl,36,44,700,page titles; text-4xl,48,56,700,marketing hero
table type bar="size px"
chart hbar type x=token y="size px" unit=px labels title="Size by step"

## Spacing and shape

data space = token,px; space-1,4; space-2,8; space-3,12; space-4,16; space-5,24; space-6,32; space-7,48; space-8,64
chart hbar space unit=px labels title="Spacing scale"

data shape = token,value,use; radius-sm,4 px,inputs and chips; radius-md,8 px,buttons and cards; radius-lg,16 px,modals; shadow-1,"0 1px 2px rgba(20,19,26,0.08)",cards at rest; shadow-2,"0 4px 12px rgba(20,19,26,0.12)",menus and hover; focus-ring,"0 0 0 3px #6E56E8 at 40%",all focusable controls
table shape

## Buttons

Each variant is listed with its exact tokens, so the rendered result can be checked against the spec. Height comes from size, never from padding guesses.

cards
### Primary
Fill brand-600, label white, no border, radius-md. Hover fill brand-500. Pressed fill #4A31B8. Disabled fill neutral-200, label neutral-500. Use once per view.
### Secondary
Fill white, label brand-600, 1 px border neutral-200, radius-md. Hover fill brand-100. Pressed fill #DDD6FA. Disabled label neutral-500.
### Ghost
No fill, label neutral-700, no border. Hover fill neutral-50. Pressed fill neutral-200. For toolbar and tertiary actions.
### Destructive
Fill danger-600, label white, radius-md. Hover fill #B03232. Always paired with a confirm step.

data sizes = size,height px,padding x px,font,icon px; sm,32,space-3 (12),text-sm,16; md,40,space-4 (16),text-base,20; lg,48,space-5 (24),text-lg,24
table sizes

### State matrix

data states = variant,rest,hover,pressed,focus,disabled; Primary,brand-600,brand-500,#4A31B8,focus-ring,neutral-200; Secondary,white,brand-100,#DDD6FA,focus-ring,white; Ghost,transparent,neutral-50,neutral-200,focus-ring,transparent; Destructive,danger-600,#B03232,#982A2A,focus-ring,neutral-200
table states

## Token file

```json
{
  "color": {
    "brand": { "600": "#5B3FD9", "500": "#6E56E8", "100": "#ECE8FD" },
    "neutral": { "900": "#14131A", "700": "#3B3947", "500": "#6B6879", "200": "#DAD8E2", "50": "#F6F5F9" },
    "danger": { "600": "#C93B3B" }
  },
  "space": { "1": 4, "2": 8, "3": 12, "4": 16, "5": 24, "6": 32, "7": 48, "8": 64 },
  "radius": { "sm": 4, "md": 8, "lg": 16 },
  "font": { "base": 16, "lg": 18, "xl": 22, "2xl": 28, "3xl": 36 }
}
```

## Open questions for review

- [ ] Darken warning-600 to pass AA, or restrict it to icons?
- [ ] Is radius-md at 8 px right for buttons, or should buttons use radius-sm?
- [ ] Keep text-4xl at 48 px, or step to 44 px to fit phone widths?
- [ ] Add a brand-700 for dark mode links?

---
[Back to the examples](/gallery/)

@title Checkout button: play, then purple
@subtitle Parameter sheet and starting presets for the click animation
@author Frontend prototype notes
@date 2026-10-19

! This page is static, so there are no sliders. Every slider is a row in the parameter table below, with its range and default. Try values in your own copy of the button, then paste the winning set into the "Parameters that worked" block at the bottom.

kpi Total duration | 760 ms | default preset | neutral
kpi Purple reached | 540 ms | 70% of the run | neutral
kpi Peak squish | 0.94x | scale at press | neutral
kpi Final color | #7C3AED | violet-600 | neutral

## What happens on click

The button runs four overlapping phases. The play animation is the icon morph (cart to play triangle to check). The purple fill starts before the morph ends, so the color change feels like part of the motion and not an afterthought.

data phases = phase,start,end; Press squish,0,90; Play icon morph,60,420; Fill to purple,300,540; Settle and check,540,760
chart range phases from=start to=end target="540 purple" title="Animation timeline (ms)"

1. Press: button scales down to the peak squish value.
2. Play: the cart icon morphs into a play triangle, then a check mark.
3. Fill: the background sweeps from the brand blue to purple, left to right.
4. Settle: scale returns to 1.0 with a small overshoot, then the label reads "Paid".

## Parameters to tune

Each row is one control you would want a slider or dropdown for. Change one at a time and keep the rest at default.

data params = parameter,default,min,max,step,unit,what it changes; Press scale,0.94,0.85,1.00,0.01,x,how hard the button squishes; Press duration,90,40,200,10,ms,speed of the squish; Icon morph duration,360,150,700,10,ms,length of the play animation; Fill delay,300,0,500,10,ms,when purple starts relative to click; Fill duration,240,100,600,10,ms,how quickly it turns purple; Overshoot,1.04,1.00,1.12,0.01,x,bounce past 1.0 when settling; Stagger,60,0,120,10,ms,gap between icon layers
table params

data options = option,choices,default; Easing,"ease-out, ease-in-out, spring, linear",spring; Fill direction,"left to right, center out, top down",left to right; Icon sequence,"cart > play > check, cart > check, play only",cart > play > check; Purple shade,"#7C3AED, #8B5CF6, #6D28D9",#7C3AED; Reduced motion,"instant swap, fade only",fade only
table options

## Easing curves compared

Progress of the fill (0 to 100) over its duration, sampled at 10 steps. Spring overshoots past 100 and settles; that overshoot is what reads as "playful".

data ease = step,ease-out,ease-in-out,spring,linear; 0,0,0,0,0; 1,27,5,22,10; 2,49,18,58,20; 3,66,35,92,30; 4,79,50,110,40; 5,88,65,108,50; 6,94,78,103,60; 7,97,88,100,70; 8,99,95,100,80; 9,100,99,100,90; 10,100,100,100,100
chart line ease x=step y=ease-out,ease-in-out,spring,linear title="Fill progress by easing" unit=%

## Starting presets

cards
### Snappy
Press 0.96, morph 220 ms, fill delay 180 ms, fill 160 ms, ease-out. Total about 480 ms. Feels like a native control.
### Playful (default)
Press 0.94, morph 360 ms, fill delay 300 ms, fill 240 ms, spring with 1.04 overshoot. Total 760 ms.
### Theatrical
Press 0.90, morph 520 ms, fill delay 380 ms, fill 360 ms, spring with 1.08 overshoot. Total about 1000 ms. Fun once, tiring on the third purchase.

## Parameters that worked

Fill this block in after trying values, then copy it from here (select the block; there is no copy button). This is the default preset as a starting point.

```css
.checkout-btn {
  --press-scale: 0.94;
  --press-ms: 90ms;
  --morph-ms: 360ms;
  --fill-delay-ms: 300ms;
  --fill-ms: 240ms;
  --overshoot: 1.04;
  --stagger-ms: 60ms;
  --easing: cubic-bezier(0.34, 1.56, 0.64, 1);
  --fill-color: #7C3AED;
}
```

```json
{
  "pressScale": 0.94,
  "pressMs": 90,
  "morphMs": 360,
  "fillDelayMs": 300,
  "fillMs": 240,
  "overshoot": 1.04,
  "staggerMs": 60,
  "easing": "spring",
  "fillDirection": "left-to-right",
  "color": "#7C3AED"
}
```

## Review checklist

- [ ] Total run is under 800 ms, so a second click is never blocked for long
- [ ] Purple is fully reached before the label changes to "Paid"
- [ ] The button ignores clicks while running (no double submit)
- [ ] White label on #7C3AED stays above 4.5:1 contrast mid-fill
- [ ] Reduced motion setting gives a fade, not a skip
- [ ] 60 fps on a mid-range phone, not only on the dev laptop

!! Do not tie the order submit to the end of the animation. Fire the request on click and let the animation run alongside it, or a slow animation reads as a slow checkout.

---
[Back to the examples](/gallery/)

@title How the API rate limiter works
@subtitle A Redis-backed token bucket in TypeScript, read once
@author Platform team
@date 2026-10-19

! In one paragraph: every caller (tenant plus route) owns a bucket that holds up to 60 tokens and refills at 1 token per second. Each request takes one token. If the bucket has a token, the request goes through; if not, it gets a 429 with a Retry-After. The whole check runs as one Lua script inside Redis, so concurrent requests cannot double-spend a token.

kpi Capacity | 60 tokens | burst size | neutral
kpi Refill | 1 token/s | 60 per minute steady | neutral
kpi Redis timeout | 25 ms | then fail open | neutral
kpi Idle expiry | 120 s | bucket resets to full | neutral

## The flow

Read this diagram top to bottom. The diamond is the only decision; everything else is bookkeeping. The dashed line is the failure path that lets traffic through.

diagram flow dir=TB title="One request through the limiter"
flow: client "Client request" user
flow: mw "rateLimit middleware" svc "Express, builds the key" focus
flow: redis "Redis" db "runs take.lua"
flow: ok "Token available?" decision
flow: app "Route handler" svc
flow: deny "429 + Retry-After" ext
flow: open "Fail open" ext "log + metric"
flow: client -> mw : request
flow: mw -> redis : EVALSHA
flow: redis -> ok : allowed, left, retry
flow: ok -> app : yes
flow: ok -> deny : no
flow: mw --> open : timeout or error
flow: open --> app : allow
flow: legend

## What a bucket does over time

Start full at 60. A burst of 60 at 1 s empties it. It refills 1 token per second, so by 30 s it holds 29. A second burst of 25 takes it to 4, and it creeps back to the 60 cap by 90 s.

data bucket = time,tokens; 0 s,60; 10 s,9; 20 s,19; 30 s,29; 40 s,13; 50 s,23; 60 s,33; 70 s,43; 80 s,53; 90 s,60; 100 s,60
chart line bucket x=time y=tokens target="60 capacity" mark="10 s burst of 60" mark="40 s burst of 25" title="Tokens left in one bucket" unit=" tokens"

## The four pieces of code

### 1. Limits config

The numbers live in one table. A route can override the default; anything not listed uses `default`.

```ts
// src/ratelimit/limits.ts
export const LIMITS: Record<string, Limit> = {
  default:         { capacity: 60,  refillPerSec: 1,  cost: 1 },
  "POST /search":  { capacity: 20,  refillPerSec: 0.5, cost: 1 },
  "POST /export":  { capacity: 5,   refillPerSec: 0.05, cost: 5 },
};
```

1. `capacity` is the burst size and the cap on stored tokens.
2. `refillPerSec` is the steady rate. It may be fractional: 0.05 is one token every 20 seconds.
3. `cost` is how many tokens one call takes. Export costs 5, so a full bucket allows exactly one export.

### 2. Building the key

```ts
// src/ratelimit/key.ts
export function bucketKey(req: Request): string {
  const who = req.auth?.tenantId ?? req.ip;
  const route = `${req.method} ${req.route.path}`;
  return `rl:{${who}}:${route}`;
}
```

1. Authenticated calls are limited per tenant, so every user in a company shares one bucket.
2. Anonymous calls fall back to the IP address.
3. The braces around `who` are a Redis Cluster hash tag. They keep all of one tenant's buckets on the same shard.

### 3. The Lua script

This is the heart of the limiter. It runs atomically on Redis, so no other command can interleave between the read and the write.

```lua
-- src/ratelimit/take.lua
local capacity = tonumber(ARGV[1])
local refill   = tonumber(ARGV[2])   -- tokens per second
local cost     = tonumber(ARGV[3])

local t   = redis.call('TIME')
local now = t[1] * 1000 + math.floor(t[2] / 1000)

local h      = redis.call('HMGET', KEYS[1], 'tokens', 'ts')
local tokens = tonumber(h[1]) or capacity
local ts     = tonumber(h[2]) or now

tokens = math.min(capacity, tokens + math.max(0, now - ts) * refill / 1000)

local allowed = 0
if tokens >= cost then
  tokens  = tokens - cost
  allowed = 1
end

redis.call('HSET', KEYS[1], 'tokens', tokens, 'ts', now)
redis.call('PEXPIRE', KEYS[1], math.ceil(capacity / refill * 1000) * 2)

local retry = 0
if allowed == 0 then retry = math.ceil((cost - tokens) / refill * 1000) end
return { allowed, math.floor(tokens), retry }
```

1. Lines 1 to 3 read the limit. Nothing is hard-coded in Lua.
2. Lines 5 and 6 take the time from Redis, not from the app server. App clocks drift; Redis has one clock.
3. Lines 8 to 10 load the bucket. A missing key means a brand-new caller, who starts full.
4. Line 12 is the refill: elapsed time times the rate, capped at capacity. Nobody runs a timer; refill is computed lazily on the next request.
5. Lines 14 to 18 decide. Tokens are taken only when there are enough for the full cost.
6. Line 21 sets the key to expire after twice the time needed to refill from empty. That is where the 120 s idle expiry comes from.
7. Lines 23 and 24 work out how long until enough tokens exist. That becomes `Retry-After`.

### 4. The middleware

```ts
// src/ratelimit/middleware.ts
export async function rateLimit(req: Request, res: Response, next: NextFunction) {
  const limit = LIMITS[`${req.method} ${req.route.path}`] ?? LIMITS.default;
  try {
    const [allowed, left, retryMs] = await withTimeout(
      redis.evalsha(TAKE_SHA, 1, bucketKey(req), limit.capacity, limit.refillPerSec, limit.cost),
      25,
    );
    res.setHeader("X-RateLimit-Remaining", left);
    if (!allowed) {
      res.setHeader("Retry-After", Math.ceil(retryMs / 1000));
      return res.status(429).json({ error: "rate_limited" });
    }
  } catch (err) {
    metrics.increment("ratelimit.fail_open");
    logger.warn({ err }, "rate limiter unavailable, allowing request");
  }
  next();
}
```

1. Picks the route's limit, or the default.
2. Calls the script by its SHA, with a 25 ms timeout so Redis trouble cannot stall the API.
3. Returns 429 with `Retry-After` in whole seconds when the script says no.
4. On any error or timeout it logs, bumps a metric and calls `next()`. The limiter fails open.

## Gotchas

!! Fail open means that if Redis is down, there is no rate limiting at all. Alert on `ratelimit.fail_open`, not just on 429s.

!! One tenant shares one bucket across all its users and API keys. A single noisy integration can lock out the rest of the company.

! `Retry-After` is rounded up to whole seconds, but the script reports milliseconds. A client that retries after exactly that many seconds will succeed; one that retries sooner will be refused again.

- **Idle buckets reset to full.** The key expires after 120 s (twice the time to refill from empty). A caller who pauses for two minutes comes back with a full bucket.
- **`EVALSHA` can fail with NOSCRIPT** after a Redis failover or restart. The client reloads the script and retries once; if that also fails you hit the fail-open path.
- **Hash tags concentrate load.** `{tenantId}` pins all of a tenant's buckets to one shard, so one very large tenant makes a hot shard.
- **Anonymous traffic is limited by IP.** Offices and mobile carriers share addresses, so legitimate users can be throttled together. Make sure `trust proxy` is set, or every request appears to come from the load balancer.
- **Tokens are fractional inside Redis** but `X-RateLimit-Remaining` is floored. A header of 0 can still mean 0.9 of a token.
- **Cost greater than capacity can never succeed.** Setting `cost: 5` with `capacity: 4` returns 429 forever and the script reports a retry time that never arrives.

---
[Back to the examples](/gallery/)

@title Payments Weekly Status
@subtitle Week of Oct 12 to Oct 16, 2026
@author Priya Raman, Engineering Manager, Payments
@date 2026-10-16
@width wide

Five of seven sprint commitments shipped and authorization success hit a six-week high. Two items slipped: EU acquirer routing (blocked on partner certificates) and ledger reconciliation v2. The chargeback rate is above its 0.50% ceiling for the second week running, and that is the risk I most want your attention on.

kpi Auth success rate | 98.7% | +0.3 pts | good
kpi p99 checkout latency | 412 ms | -9% | good
kpi Chargeback rate | 0.61% | +0.07 pts | bad
kpi Sprint commitments done | 71% | 5 of 7 | bar

## What shipped

data shipped = item,owner,status,result
data shipped += Retry with jitter for issuer timeouts,Dana Okafor,Done,"Auth success 98.4% to 98.7%; no rollbacks"
data shipped += Idempotency keys on the refunds API,Luis Herrera,Done,"Duplicate refunds: 14 the week before, 0 since Wednesday"
data shipped += Apple Pay token refresh fix,Mei Tanaka,Done,"iOS checkout failures down 62%"
data shipped += Settlement-lag dashboard,Aiko Brandt,Done,"On-call can see lag per bank; used in Thursday's page"
data shipped += PCI scope document refresh,Tomas Reyes,Done,"Signed off by the assessor Oct 15"

table shipped

grid 2

data auth = week,rate
data auth += Sep 7,98.2
data auth += Sep 14,98.1
data auth += Sep 21,98.2
data auth += Sep 28,97.6
data auth += Oct 5,98.4
data auth += Oct 12,98.7

data cb = week,rate
data cb += Sep 21,0.44
data cb += Sep 28,0.47
data cb += Oct 5,0.54
data cb += Oct 12,0.61

chart line auth x=week y=rate unit=% min=97 max=99.5 target="99.0 goal" mark="Sep 28 Issuer outage" mark="Oct 12 Retry jitter" labels=end title="Authorization success rate, weekly"
chart bar cb x=week y=rate unit=% target="0.50 ceiling" focus="Oct 12" labels title="Chargeback rate, weekly"

## What slipped

data slipped = item,owner,was due,now due,status,why
data slipped += EU acquirer routing,Marcus Webb,Oct 14,Oct 23,Blocked,"Acquirer sandbox certificates arrived 6 days late"
data slipped += Ledger reconciliation v2,Samir Patel,Oct 16,Oct 21,At risk,"2 partner file formats still failing; 3 of 8 partners in shadow mode"

table slipped

! The EU slip does not move the Nov 1 pilot yet. It does if certificates are not live by Oct 23.

## Risks

!! Chargeback rate is 0.61% against our 0.50% ceiling. Our acquirer opens a formal review at 0.65%, which brings fines starting at $25,000 per month and a remediation plan. At the current trend we cross that line in about two weeks.

data risks = risk,likelihood,impact,owner,mitigation
data risks += Chargebacks cross the 0.65% acquirer threshold,High,"Fines from $25,000 per month plus a remediation plan",Tomas Reyes,"Friendly-fraud rule tuning ships Oct 20; weekly review with Risk"
data risks += EU routing slips past the Nov 1 pilot,Medium,"Pilot (about $2.3M monthly volume) moves to December",Marcus Webb,"Escalated to the acquirer account lead; fallback is the current acquirer at +0.3 pts in fees"
data risks += Ledger v2 not ready for the Oct 30 quarter-end close,Medium,"Finance keeps manual reconciliation, about 12 analyst-hours per week",Samir Patel,"Prioritize the 5 remaining partners by volume; daily check-in"
data risks += Apple Pay coverage gap while Mei is out Oct 26 to 30,Low,"Slower response to wallet incidents",Dana Okafor,"Runbook handoff and a named backup by Oct 23"

table risks

## Next week

step Ship chargeback rule tuning to production | Tue Oct 20 | Tomas Reyes
step Finish ledger v2 partner file fixes (5 of 8 partners in shadow) | Wed Oct 21 | Samir Patel
step Chargeback review with Risk and Finance | Thu Oct 22 | Priya Raman
step Route 10% of EU traffic to the new acquirer | Fri Oct 23 | Marcus Webb
step Move settlement-lag alerts to paging | Fri Oct 23 | Aiko Brandt

## Decisions needed from you

1. A call to the acquirer's regional head by Oct 21 to ask for priority on the EU certificates. This is the only thing that protects the Nov 1 pilot date.
2. Approval for one contractor for 6 weeks ($38,000) to cover Mei's absence and the ledger v2 backlog.
3. Agreement that if chargebacks reach 0.65% before Oct 30, we pause new-merchant onboarding until the rate is back under 0.55%.

---
[Back to the examples](/gallery/)

@title Checkout Outage on October 18
@subtitle Incident report: 47 minutes on Sunday morning
@author Incident review team, Customer Platform
@date 2026-10-19

!!! Customers could not complete a purchase on our website or app for 47 minutes, from 10:12 AM to 10:59 AM Eastern on Sunday, October 18. No customer was charged twice and no payment data was exposed.

kpi Outage length | 47 min | longest this year | bad
kpi Failed checkout attempts | 27,900 | 67% of attempts | bad
kpi Orders lost (estimate) | 10,500 | about $672,000 | bad
kpi Customers charged twice | 0 | confirmed by Finance | good

## In plain terms

Every time a customer clicks Pay, our checkout service borrows one of a fixed number of shared lines to the orders database, saves the order, and hands the line back. We normally allow 200 lines at once. A routine settings change on Sunday morning cut that number to 20. Sunday morning is one of our busiest times, so the 20 lines were used up within minutes and everyone else got an error.

The change was meant for our test environment, which has very little traffic. It was copied into the live settings by mistake. Fixing it took 47 minutes because our usual way of undoing a change refused to run while checkout was unhealthy.

diagram flow dir=LR title="What happens when a customer clicks Pay"
flow: cust "Customer" user
flow: site "Website or app" svc
flow: co "Checkout service" svc
flow: pool "Shared database lines" svc "Limit was 200, became 20" focus
flow: db "Orders database" db
flow: cust -> site : clicks Pay
flow: site -> co
flow: co -> pool : needs a line
flow: pool -> db : saves order

## Impact

data impact = measure,value,note
data impact += Checkout attempts during the outage,"41,800","Normal Sunday-morning volume"
data impact += Attempts that failed,"27,900","67%; the rest got through as lines were freed up"
data impact += Customers who gave up,"10,500","Did not complete an order within 24 hours"
data impact += Estimated lost sales,"$672,000","10,500 orders at the $64 average order"
data impact += Support tickets opened,"1,860","Mostly 'my payment failed'; 94% answered within 4 hours"
data impact += Customers charged twice,0,"Failed attempts never reached the payment step"
data impact += Payment card data exposed,0,"Not involved in this incident"

table impact

The chart shows the share of checkout attempts that succeeded. It dropped from 99% to about 30% within minutes of the change and stayed there until engineers fixed the setting by hand.

data success = time,rate
data success += 10:00,99.4
data success += 10:04,99.3
data success += 10:08,99.4
data success += 10:12,99.2
data success += 10:16,42.0
data success += 10:20,31.0
data success += 10:24,30.0
data success += 10:28,32.0
data success += 10:32,31.0
data success += 10:36,33.0
data success += 10:40,30.0
data success += 10:44,32.0
data success += 10:48,31.0
data success += 10:52,34.0
data success += 10:56,81.0
data success += 11:00,99.1
data success += 11:04,99.4

chart line success x=time y=rate unit=% min=0 max=100 target="99 usual" mark="10:12 Change live" mark="10:52 Fix applied" title="Checkout attempts that succeeded"

## Timeline

All times are Eastern, Sunday October 18.

data timeline = time,what happened,who
data timeline += 10:12 AM,"A routine settings change is released to all customers at once","Automated release system"
data timeline += 10:16 AM,"Checkout failures climb as Sunday-morning shoppers arrive","n/a"
data timeline += 10:19 AM,"Alert fires after failures stay high for 5 minutes; the on-call engineer is paged","Nia Osei"
data timeline += 10:24 AM,"Incident declared; an incident commander and 4 engineers join","Rafael Mendes"
data timeline += 10:31 AM,"First fix, undoing the change, is blocked by the release system's safety check","Rafael Mendes"
data timeline += 10:38 AM,"Cause found: the database line limit is 20, not 200","Nia Osei"
data timeline += 10:52 AM,"Engineers set the limit back to 200 by hand, bypassing the release system","Nia Osei and Rafael Mendes"
data timeline += 10:59 AM,"Checkout success is back to 99%; incident closed at 11:30 AM after monitoring","Rafael Mendes"

table timeline

data phases = phase,start,end
data phases += Not yet noticed,0,7
data phases += Finding the cause,7,26
data phases += Fixing,26,40
data phases += Recovering,40,47

chart range phases from=start to=end unit=min title="Where the 47 minutes went (minutes after 10:12 AM)"

## Why it happened

Three things lined up. Any one of them alone would likely have limited the damage.

1. A test-environment value was copied into the live settings file. The value, 20, is correct for the test environment but far too small for live traffic.
2. Review did not catch it. The reviewer saw a one-line change and the tool did not show what the live value had been before.
3. There was no gradual rollout, and no easy undo. The change reached every customer at once, and the release system will not undo a change while checkout is unhealthy, which is exactly when an undo is needed.

Detection was also slower than it should be: the alert waits for 5 minutes of sustained failures, so 7 minutes passed before anyone was paged.

### For engineers: the change

```diff
# config/prod/checkout-service.yaml
 database:
-  pool_max_connections: 200
+  pool_max_connections: 20
```

```yaml
# release gate that blocked the rollback
post_deploy_gate:
  require: checkout_success_rate >= 95
  applies_to: [deploy, rollback]
```

## What we are changing

data actions = action,owner,due,status
data actions += Live setting restored to 200 and locked against edits outside the release system,Rafael Mendes,Oct 18,Done
data actions += Page the on-call engineer after 2 minutes of failures instead of 5,Nia Osei,Oct 19,Done
data actions += Show old and new live values side by side in every settings review,Tessa Lindqvist,Oct 23,In progress
data actions += Automatically block any setting that cuts a live limit by more than half unless a second person approves,Tessa Lindqvist,Oct 30,In progress
data actions += Allow an undo even when checkout is unhealthy,Rafael Mendes,Oct 27,In progress
data actions += Roll out settings to 5% of customers first and to everyone after 10 healthy minutes,Jun Park,Nov 13,In progress
data actions += "Email and a $10 credit to the 10,500 customers who did not complete an order",Customer Support,Oct 22,In progress

table actions

! Progress on every action above is reviewed at the Thursday reliability meeting until all are Done.

## Words used in this report

- **Database lines (connection pool):** the fixed number of simultaneous links between checkout and the orders database.
- **Release system:** the tool that delivers code and settings changes to the live site.
- **Rollback (undo):** returning to the previous version of a change.
- **On-call engineer:** the person who is responsible for answering alerts outside office hours.
- **Alert:** an automatic message that tells on-call something is wrong.

---
[Back to the examples](/gallery/)

@title How Webhook Retries Work
@subtitle What happens when your endpoint does not answer with a 2xx

When an event such as order.paid fires, we deliver it to your endpoint with a POST. If that attempt fails, we keep trying on a growing schedule for about 36 hours before giving up.

diagram retry dir=TB title="Webhook delivery and retry path"
retry: evt "Event created" svc "for example order.paid"
retry: q "Delivery queue" queue
retry: send "Worker POSTs to your endpoint" fn "10 s timeout"
retry: ok "2xx within 10 s?" decision
retry: done "Delivered" svc focus
retry: perm "410 Gone?" decision
retry: off "Endpoint disabled" ext "owner emailed"
retry: left "Attempts left?" decision
retry: wait "Wait with backoff" fn "30 s up to 24 h"
retry: dlq "Dead-letter queue" queue "kept 14 days"
retry: replay "Manual replay" team "dashboard or API"
retry: evt -> q : enqueue
retry: q -> send : next attempt
retry: send -> ok
retry: ok -> done : yes
retry: ok -> perm : no
retry: perm -> off : yes
retry: perm -> left : no
retry: left -> wait : yes
retry: left -> dlq : no
retry: wait --> q : requeue
retry: dlq --> replay : on request
retry: group loop "Retry loop" q, send, ok, perm, left, wait
retry: legend

## In short

Delivery is at least once. Any 2xx response within 10 seconds counts as success. A timeout, a connection error, a 5xx and every 4xx other than 410 all count as a failure and enter the retry loop.

- **Up to 8 attempts.** The first is immediate, then 7 retries after waits of 30 s, 2 min, 10 min, 1 h, 3 h, 8 h and 24 h. Each wait gets up to 20% random jitter so a recovering server is not hit by every queued event at once.
- **Retry-After is respected.** On a 429 or 503 with a Retry-After header we wait for the longer of that value and the scheduled delay.
- **410 Gone stops everything.** We treat it as a deliberate removal, disable the endpoint and email its owner. Queued events wait for you to re-enable it.
- **After the 8th failure** the event moves to the dead-letter queue. It is kept for 14 days and can be replayed from the dashboard or with `POST /v1/webhooks/deliveries/{id}/replay`.
- **Circuit breaker.** An endpoint that fails 100 events in a row is paused and its owner is emailed, so a dead server does not accumulate a backlog.

## The retry schedule

data backoff = retry,wait
data backoff += Retry 1,0.5
data backoff += Retry 2,2
data backoff += Retry 3,10
data backoff += Retry 4,60
data backoff += Retry 5,180
data backoff += Retry 6,480
data backoff += Retry 7,1440

chart hbar backoff x=retry y=wait unit=min labels title="Wait before each retry"

data plan = retry,wait before it,total since first try,jitter window
data plan += 1,30 s,30 s,24 s to 36 s
data plan += 2,2 min,2.5 min,96 s to 144 s
data plan += 3,10 min,12.5 min,8 to 12 min
data plan += 4,1 h,about 1 h 12 min,48 to 72 min
data plan += 5,3 h,about 4 h 12 min,2.4 to 3.6 h
data plan += 6,8 h,about 12 h 12 min,6.4 to 9.6 h
data plan += 7,24 h,about 36 h 12 min,19.2 to 28.8 h

table plan

## What your endpoint should do

Because delivery is at least once, the same event can arrive more than once, for example when your server processed it but its 200 was lost. Every retry carries the same event id, so deduplicate on it. Respond fast and do the slow work afterward.

```http
POST /hooks/payments HTTP/1.1
Webhook-Id: evt_01JA7Q3M
Webhook-Attempt: 3
Webhook-Timestamp: 1760803200
Content-Type: application/json
```

```python
@app.post("/hooks/payments")
def receive():
    event = request.get_json()
    if already_processed(event["id"]):   # retries reuse the same id
        return "", 200
    queue.put(event)                     # slow work happens later
    return "", 200
```

! Return a 2xx only after you have safely stored the event. A 2xx tells us never to send it again.

---
[Back to the examples](/gallery/)

@title Q4 ticket triage: 30 tickets into Now / Next / Later / Cut
@subtitle Harbor invoicing, ENG board, proposed ordering for the last six weeks of the quarter
@author Claude, Engineering planning
@date 2026-10-19
@width wide

! This page is a static snapshot, not an editor. The proposed buckets are pre-filled below. To change one, move the ticket line in the export block at the bottom and paste that block back.

## The proposal in numbers

kpi Now | 7 tickets | 24 pts | neutral
kpi Next | 9 tickets | 50 pts | neutral
kpi Later | 8 tickets | 92 pts | neutral
kpi Cut | 6 tickets | 65 pts | bad

data load = bucket,tickets,points; Now,7,24; Next,9,50; Later,8,92; Cut,6,65
chart bar load y=points labels title="Estimated points per bucket"

Team velocity is about 32 pts per two-week sprint, so Now fits the first sprint with 8 pts of slack for interrupts. Now plus Next (74 pts) fills the quarter at about 2.3 sprints.

## Ticket data

data now = id,title,owner,pts,impact,why; ENG-2041,Fix duplicate invoice emails on retry,Priya,3,5,Customers get two invoice emails and 14 support tickets came in this month
data now += ENG-2047,Rotate Stripe webhook signing secret,Marcus,2,5,Old secret expires 2026-11-06
data now += ENG-2052,Invoice PDF renders blank on Safari 17,Lena,3,4,Affects 11% of portal sessions
data now += ENG-2058,Raise Postgres connection pool ceiling,Marcus,1,4,Pool saturated twice during month-end runs
data now += ENG-2063,Tax ID validation for EU customers,Priya,8,5,VAT rule change takes effect 2026-11-30
data now += ENG-2066,CSV export times out above 50k rows,Jonas,5,4,Three enterprise accounts blocked
data now += ENG-2070,Rate-limit the login endpoint,Lena,2,4,Credential-stuffing spike seen on 2026-10-11

data next = id,title,owner,pts,impact,why; ENG-2075,Recurring invoice scheduler UI,Aiko,8,4,Top-voted request on the roadmap board
data next += ENG-2079,Bulk-send reminders for overdue invoices,Aiko,5,4,Cuts days-sales-outstanding for pilot customers
data next += ENG-2083,Audit log for permission changes,Tomas,5,3,Needed for the SOC 2 evidence request in Q1
data next += ENG-2086,Multi-currency rounding mismatch on credit notes,Priya,3,4,Off by 1 cent on JPY and KWD so finance reconciles by hand
data next += ENG-2090,SAML SSO for the Team plan,Tomas,13,4,Blocks two deals worth $96k ARR
data next += ENG-2092,Replace moment.js with date-fns,Jonas,3,2,Cuts 70 KB from the bundle
data next += ENG-2095,Webhook delivery retries dashboard,Marcus,5,3,Support currently reads logs by hand
data next += ENG-2098,Portal: download all invoices as ZIP,Lena,3,3,Requested by accountants at year end
data next += ENG-2101,Onboarding checklist v2,Aiko,5,3,Activation is 41% and the target is 50%

data later = id,title,owner,pts,impact,why; ENG-2104,Dark mode for the customer portal,unassigned,5,2,"Nice to have; no revenue link"
data later += ENG-2107,Migrate Sidekiq jobs to Temporal,unassigned,21,3,Pays off only once job volume doubles
data later += ENG-2110,Quote-to-invoice conversion,unassigned,13,3,Waiting on the quotes beta feedback
data later += ENG-2113,Slack notification when an invoice is paid,unassigned,3,2,Small but not urgent
data later += ENG-2116,Localize the UI into German and French,unassigned,13,3,Depends on the EU launch decision
data later += ENG-2119,Public API v2 cursor pagination,unassigned,8,3,Offset pagination is slow past page 400
data later += ENG-2122,Accessibility pass on the invoice editor,unassigned,8,3,Schedule with the WCAG audit in Q1
data later += ENG-2125,Usage-based billing prototype,unassigned,21,3,"Strategic bet; needs a product spec first"

data cut = id,title,owner,pts,impact,why; ENG-2128,Gantt view of payment timelines,unassigned,13,1,No customer has asked for it
data cut += ENG-2131,Emoji reactions on invoice comments,unassigned,3,1,Novelty feature
data cut += ENG-2134,Rewrite the PDF engine in Rust,unassigned,34,2,Cost is far above benefit and ENG-2052 fixes the actual bug
data cut += ENG-2137,Rounding fix for quotes,unassigned,2,1,Duplicate of ENG-2086
data cut += ENG-2140,Legacy XML export,unassigned,5,1,Zero uses in 12 months
data cut += ENG-2143,Blockchain payment rail spike,unassigned,8,1,No demand and a compliance burden

## Now

Customer-facing money bugs, security, and the EU VAT deadline. Everything here has a date or an active complaint behind it.

table now heat=impact

## Next

Revenue and retention work that starts as soon as Now clears. Order within the table is the suggested pick-up order.

table next heat=impact

## Later

Valuable or strategic, but large or waiting on a decision. Revisit at Q1 planning.

table later

## Cut

Close these with a short comment. None has a customer, a deadline, or usage data behind it.

table cut

## Calls worth a second look

table = ticket,placed,alternative,what would flip it; ENG-2090 SAML SSO,Next,Now,Both deals sign before Dec 15 and need SAML in the contract; ENG-2086 credit note rounding,Next,Now,Finance says the monthly manual fix is more than 2 hours; ENG-2092 date-fns,Next,Cut,No bundle-size goal is set this quarter; ENG-2107 Temporal,Later,Cut,Job volume stays flat through Q2

## Export: paste this back

Final ordering as Markdown, one rationale line per bucket, tickets in pick-up order.

```md
## Now (7 tickets, 24 pts)
_Customer-facing money bugs, security, and the 2026-11-30 EU VAT deadline; fits one sprint with slack._
1. ENG-2047 Rotate Stripe webhook signing secret (2 pts, Marcus)
2. ENG-2041 Fix duplicate invoice emails on retry (3 pts, Priya)
3. ENG-2070 Rate-limit the login endpoint (2 pts, Lena)
4. ENG-2058 Raise Postgres connection pool ceiling (1 pt, Marcus)
5. ENG-2052 Invoice PDF renders blank on Safari 17 (3 pts, Lena)
6. ENG-2066 CSV export times out above 50k rows (5 pts, Jonas)
7. ENG-2063 Tax ID validation for EU customers (8 pts, Priya)

## Next (9 tickets, 50 pts)
_Revenue and retention work that unblocks sales and activation once Now clears._
1. ENG-2090 SAML SSO for the Team plan (13 pts, Tomas)
2. ENG-2075 Recurring invoice scheduler UI (8 pts, Aiko)
3. ENG-2079 Bulk-send reminders for overdue invoices (5 pts, Aiko)
4. ENG-2086 Multi-currency rounding mismatch on credit notes (3 pts, Priya)
5. ENG-2101 Onboarding checklist v2 (5 pts, Aiko)
6. ENG-2083 Audit log for permission changes (5 pts, Tomas)
7. ENG-2095 Webhook delivery retries dashboard (5 pts, Marcus)
8. ENG-2098 Portal: download all invoices as ZIP (3 pts, Lena)
9. ENG-2092 Replace moment.js with date-fns (3 pts, Jonas)

## Later (8 tickets, 92 pts)
_Valuable or strategic but large or waiting on a decision; revisit at Q1 planning._
- ENG-2125 Usage-based billing prototype (21 pts)
- ENG-2110 Quote-to-invoice conversion (13 pts)
- ENG-2116 Localize the UI into German and French (13 pts)
- ENG-2119 Public API v2 cursor pagination (8 pts)
- ENG-2122 Accessibility pass on the invoice editor (8 pts)
- ENG-2107 Migrate Sidekiq jobs to Temporal (21 pts)
- ENG-2104 Dark mode for the customer portal (5 pts)
- ENG-2113 Slack notification when an invoice is paid (3 pts)

## Cut (6 tickets, 65 pts)
_No customer, deadline, or usage data behind them; close with a comment._
- ENG-2134 Rewrite the PDF engine in Rust (34 pts)
- ENG-2128 Gantt view of payment timelines (13 pts)
- ENG-2143 Blockchain payment rail spike (8 pts)
- ENG-2140 Legacy XML export (5 pts)
- ENG-2131 Emoji reactions on invoice comments (3 pts)
- ENG-2137 Rounding fix for quotes (2 pts, duplicate of ENG-2086)
```

---
[Back to the examples](/gallery/)

@title Feature flag review: flags.yaml, 14 flags
@subtitle Proposed change set for the 2026-10-22 release, with the dependency check already run
@author Claude, Platform
@date 2026-10-19
@width wide

! This is a static review, not an editor. The proposed values are pre-filled in the tables. The diff to apply is the last block on the page.

## Summary

kpi Flags | 14 | 6 areas | neutral
kpi Enabled today | 8 | of 14 | neutral
kpi Enabled after | 12 | +4 flags | good
kpi Dependency warnings | 0 | in this change set | good

!! One flag you may be tempted to enable, ai_assistant, would fail its dependency check: platform_audit_log is off. The proposal leaves it off.

## Flags by area

data flags = area,flag,today,proposed,rollout today,rollout proposed,requires,owner; checkout,checkout_v2,On,On,100,100,payments_tokenization,Dana
data flags += checkout,checkout_express_pay,Off,On,0,10,"checkout_v2 + payments_tokenization",Dana
data flags += checkout,checkout_saved_cards,On,On,60,100,payments_tokenization,Dana
data flags += payments,payments_tokenization,On,On,100,100,none,Ravi
data flags += payments,payments_3ds2,On,On,100,100,payments_tokenization,Ravi
data flags += search,search_typeahead,On,On,100,100,none,Mei
data flags += search,search_embeddings,Off,On,0,100,platform_event_bus,Mei
data flags += search,search_semantic,Off,On,0,25,search_embeddings,Mei
data flags += billing,billing_invoices_v2,On,On,100,100,none,Omar
data flags += billing,billing_tax_eu,On,On,100,100,billing_invoices_v2,Omar
data flags += billing,billing_usage_metering,Off,On,0,5,"billing_invoices_v2 + platform_event_bus",Omar
data flags += platform,platform_event_bus,On,On,100,100,none,Sofia
data flags += platform,platform_audit_log,Off,Off,0,0,none,Sofia
data flags += assistant,ai_assistant,Off,Off,0,0,"search_semantic + platform_audit_log",Jun

table flags sort=area

### Changed in this proposal

table = flag,change,reason; checkout_express_pay,Off to On at 10%,Canary for the one-tap pay button and its prerequisites are already on; search_embeddings,Off to On at 100%,Index is backfilled and must be on before semantic search; search_semantic,Off to On at 25%,A quarter of traffic first and embeddings must go first; billing_usage_metering,Off to On at 5%,Pilot with the six metered customers; checkout_saved_cards,Rollout 60% to 100%,Error rate matched control for 7 days

## Dependency check

Each row is a flag in the proposed state that has prerequisites, checked against the prerequisite's proposed state.

data deps = flag,prerequisite,prerequisite after change,result; checkout_v2,payments_tokenization,On,Go
data deps += checkout_express_pay,checkout_v2,On,Go
data deps += checkout_express_pay,payments_tokenization,On,Go
data deps += checkout_saved_cards,payments_tokenization,On,Go
data deps += payments_3ds2,payments_tokenization,On,Go
data deps += search_embeddings,platform_event_bus,On,Go
data deps += search_semantic,search_embeddings,On (enabled in this change),Go
data deps += billing_tax_eu,billing_invoices_v2,On,Go
data deps += billing_usage_metering,billing_invoices_v2,On,Go
data deps += billing_usage_metering,platform_event_bus,On,Go

table deps

### What-if: enabling ai_assistant

data whatif = flag,prerequisite,prerequisite after change,result; ai_assistant,search_semantic,On,Go
data whatif += ai_assistant,platform_audit_log,Off,Blocked

table whatif

!! Enabling ai_assistant now would run it without an audit log. Enable platform_audit_log first (Sofia estimates 2 days), then ai_assistant.

### Blast radius if a prerequisite is turned off

data blast = prerequisite,dependents that break,count; payments_tokenization,"checkout_v2, checkout_express_pay, checkout_saved_cards, payments_3ds2",4
data blast += platform_event_bus,"search_embeddings, billing_usage_metering",2
data blast += billing_invoices_v2,"billing_tax_eu, billing_usage_metering",2
data blast += search_embeddings,search_semantic,1
data blast += checkout_v2,checkout_express_pay,1

table blast sort=-count bar=count

## Dependency graph

An arrow points from a flag to the flag it requires. The blocked path is the one the dependency check rejects.

diagram depgraph dir=LR title="Flag prerequisites after the proposed change"
depgraph: payments_tokenization "payments_tokenization" svc "On" focus
depgraph: checkout_v2 "checkout_v2" svc "On"
depgraph: checkout_express_pay "checkout_express_pay" svc "Off to On 10%" focus
depgraph: checkout_saved_cards "checkout_saved_cards" svc "60% to 100%"
depgraph: payments_3ds2 "payments_3ds2" svc "On"
depgraph: platform_event_bus "platform_event_bus" svc "On"
depgraph: platform_audit_log "platform_audit_log" ext "Off"
depgraph: search_embeddings "search_embeddings" svc "Off to On 100%" focus
depgraph: search_semantic "search_semantic" svc "Off to On 25%" focus
depgraph: billing_invoices_v2 "billing_invoices_v2" svc "On"
depgraph: billing_tax_eu "billing_tax_eu" svc "On"
depgraph: billing_usage_metering "billing_usage_metering" svc "Off to On 5%" focus
depgraph: ai_assistant "ai_assistant" ext "Stays Off"
depgraph: checkout_v2 -> payments_tokenization
depgraph: checkout_express_pay -> checkout_v2, payments_tokenization
depgraph: checkout_saved_cards -> payments_tokenization
depgraph: payments_3ds2 -> payments_tokenization
depgraph: search_embeddings -> platform_event_bus
depgraph: search_semantic -> search_embeddings
depgraph: billing_tax_eu -> billing_invoices_v2
depgraph: billing_usage_metering -> billing_invoices_v2, platform_event_bus
depgraph: ai_assistant -> search_semantic
depgraph: ai_assistant -x- platform_audit_log : prereq off
depgraph: group g_pay "Payments" payments_tokenization, payments_3ds2
depgraph: group g_checkout "Checkout" checkout_v2, checkout_express_pay, checkout_saved_cards
depgraph: group g_search "Search" search_embeddings, search_semantic
depgraph: group g_billing "Billing" billing_invoices_v2, billing_tax_eu, billing_usage_metering
depgraph: group g_platform "Platform" platform_event_bus, platform_audit_log
depgraph: legend

## Order of operations

1. Deploy the config change with search_embeddings first, since search_semantic requires it.
2. Raise checkout_saved_cards to 100%.
3. Enable checkout_express_pay at 10% and watch the payment error rate for 24 hours.
4. Enable billing_usage_metering at 5%.
5. Move search_semantic to 25% once the embeddings index shows no lag.

## Resulting flags.yaml

```yaml
# flags.yaml after the proposed change
checkout_v2:
  enabled: true
  rollout: 100
  requires: [payments_tokenization]
checkout_express_pay:
  enabled: true
  rollout: 10
  requires: [checkout_v2, payments_tokenization]
checkout_saved_cards:
  enabled: true
  rollout: 100
  requires: [payments_tokenization]
payments_tokenization:
  enabled: true
  rollout: 100
payments_3ds2:
  enabled: true
  rollout: 100
  requires: [payments_tokenization]
search_typeahead:
  enabled: true
  rollout: 100
search_embeddings:
  enabled: true
  rollout: 100
  requires: [platform_event_bus]
search_semantic:
  enabled: true
  rollout: 25
  requires: [search_embeddings]
billing_invoices_v2:
  enabled: true
  rollout: 100
billing_tax_eu:
  enabled: true
  rollout: 100
  requires: [billing_invoices_v2]
billing_usage_metering:
  enabled: true
  rollout: 5
  requires: [billing_invoices_v2, platform_event_bus]
platform_event_bus:
  enabled: true
  rollout: 100
platform_audit_log:
  enabled: false
  rollout: 0
ai_assistant:
  enabled: false
  rollout: 0
  requires: [search_semantic, platform_audit_log]
```

## Copy diff: changed keys only

Paste this over the matching keys. Five flags change and nine are untouched.

```yaml
checkout_express_pay:
  enabled: true      # was false
  rollout: 10        # was 0
checkout_saved_cards:
  rollout: 100       # was 60
search_embeddings:
  enabled: true      # was false
  rollout: 100       # was 0
search_semantic:
  enabled: true      # was false
  rollout: 25        # was 0
billing_usage_metering:
  enabled: true      # was false
  rollout: 5         # was 0
```

---
[Back to the examples](/gallery/)

@title Support prompt tuning: Tallyhouse reply agent
@subtitle Draft v2 of the system prompt, four variable slots, three sample inputs already filled in
@author Claude, Support engineering
@date 2026-10-19
@width wide

! This is a static review, not a live editor. The template, the three filled-in renderings and the size estimates are all written out below. Edit the template block, paste it back, and the renderings are the ones to re-check.

## Size at a glance

kpi Template | ~725 characters | ~180 tokens | neutral
kpi Slots | 4 | all required | neutral
kpi Largest filled prompt | ~800 characters | ~200 tokens | good

Counts are hand estimates at about 4 characters per token. Treat them as plus or minus 10%.

## The four slots

table = slot,filled from,example,limit; **{{agent_name}}**,Persona config,Mira,30 characters; **{{company_name}}**,Account record,Tallyhouse,40 characters; **{{customer_tier}}**,CRM lookup,Standard or Priority or Trial,one of 3 values; **{{kb_snippets}}**,Retrieval top 3,[KB-114] Refunds: 30 days from delivery,1200 characters

## Template with slots highlighted

You are **{{agent_name}}**, a support specialist at **{{company_name}}**.

Customer tier: **{{customer_tier}}**.

Rules:

1. If the customer mentions legal action, a chargeback, or a safety issue, stop and write `ESCALATE: <one-line reason>`.
2. Answer only from the knowledge base excerpts below. If they do not cover the question, say so and offer to hand off to a human.
3. Never promise refunds, credits, or delivery dates. Describe the policy and let a human approve exceptions.
4. Keep replies under 120 words, plain text, no headings.
5. Match the customer's tone and apologize once at most.
6. For Priority customers, offer a callback in the first reply when the issue blocks their work.

Knowledge base excerpts:

**{{kb_snippets}}**

### What changed from the previous draft

- The escalation rule moved from the last line to rule 1, so it is read before the "answer from the excerpts" rule. Sample 3 is the test for this.
- The rule numbers shifted down by one. Nothing else was reworded.

## Paste-ready template

```
You are {{agent_name}}, a support specialist at {{company_name}}.

Customer tier: {{customer_tier}}.

Rules:
1. If the customer mentions legal action, a chargeback, or a safety issue, stop and write ESCALATE: <one-line reason>.
2. Answer only from the knowledge base excerpts below. If they do not cover the question, say so and offer to hand off to a human.
3. Never promise refunds, credits, or delivery dates. Describe the policy and let a human approve exceptions.
4. Keep replies under 120 words, plain text, no headings.
5. Match the customer's tone and apologize once at most.
6. For Priority customers, offer a callback in the first reply when the issue blocks their work.

Knowledge base excerpts:
{{kb_snippets}}
```

## Sample inputs, rendered

data samples = sample,customer message,tier,characters,tokens; 1 Refund window,"Hi, I bought a lamp 3 weeks ago and it flickers. Can I get my money back?",Standard,800,200
data samples += 2 Blocked export,"Our CSV export keeps failing and payroll is due today.",Priority,795,199
data samples += 3 Chargeback threat,"This is the third time. I will dispute the charge with my bank.",Trial,706,177

table samples bar=tokens

### Sample 1: refund window, Standard tier

Customer message: "Hi, I bought a lamp 3 weeks ago and it flickers. Can I get my money back?"

A good reply states the 30-day window, says the lamp qualifies if unused or defective, and does not promise the refund.

```
You are Mira, a support specialist at Tallyhouse.

Customer tier: Standard.

Rules:
1. If the customer mentions legal action, a chargeback, or a safety issue, stop and write ESCALATE: <one-line reason>.
2. Answer only from the knowledge base excerpts below. If they do not cover the question, say so and offer to hand off to a human.
3. Never promise refunds, credits, or delivery dates. Describe the policy and let a human approve exceptions.
4. Keep replies under 120 words, plain text, no headings.
5. Match the customer's tone and apologize once at most.
6. For Priority customers, offer a callback in the first reply when the issue blocks their work.

Knowledge base excerpts:
[KB-114] Refunds: 30 days from delivery for unused items. [KB-118] Return labels are emailed within 1 business day.
```

### Sample 2: blocked export, Priority tier

Customer message: "Our CSV export keeps failing and payroll is due today."

A good reply cites the 50,000 row limit, suggests date filters, and offers a callback in this first message.

```
You are Mira, a support specialist at Tallyhouse.

Customer tier: Priority.

Rules:
1. If the customer mentions legal action, a chargeback, or a safety issue, stop and write ESCALATE: <one-line reason>.
2. Answer only from the knowledge base excerpts below. If they do not cover the question, say so and offer to hand off to a human.
3. Never promise refunds, credits, or delivery dates. Describe the policy and let a human approve exceptions.
4. Keep replies under 120 words, plain text, no headings.
5. Match the customer's tone and apologize once at most.
6. For Priority customers, offer a callback in the first reply when the issue blocks their work.

Knowledge base excerpts:
[KB-302] CSV export is limited to 50,000 rows per request. [KB-305] Use date filters to split large exports.
```

### Sample 3: chargeback threat, Trial tier, no excerpts

Customer message: "This is the third time. I will dispute the charge with my bank."

A good reply is only `ESCALATE: customer threatens a chargeback after repeated contacts`. If it tries to answer from empty excerpts, rule 1 is not winning and the prompt needs a stronger escalation line.

```
You are Mira, a support specialist at Tallyhouse.

Customer tier: Trial.

Rules:
1. If the customer mentions legal action, a chargeback, or a safety issue, stop and write ESCALATE: <one-line reason>.
2. Answer only from the knowledge base excerpts below. If they do not cover the question, say so and offer to hand off to a human.
3. Never promise refunds, credits, or delivery dates. Describe the policy and let a human approve exceptions.
4. Keep replies under 120 words, plain text, no headings.
5. Match the customer's tone and apologize once at most.
6. For Priority customers, offer a callback in the first reply when the issue blocks their work.

Knowledge base excerpts:
(no matching excerpts)
```

---
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