Every major LLM API now caches prompt prefixes: send the same beginning twice and the second call is cheaper and faster. What vendors rarely say is how long a cached prefix survives. Anthropic documents it (5 min, or 1 h on request); OpenAI gives a range ("5 to 10 minutes of inactivity, up to an hour", 24 h on opt-in); DeepSeek says "hours to days". Z.ai, Moonshot (Kimi) and Mistral publish nothing. I could not find a page that measures it.
So I measured it.
Three layers must all cooperate. Any one of them broken and copy silently does nothing — no error, no clipboard. 🧩
[ remote app / tmux copy-mode ] → OSC 52 escape → [ ssh ] → [ local terminal ] → clipboard
This note distinguishes server-side constrained decoding from prompt-only formatting. In constrained decoding, the inference server masks invalid next tokens while generating; it does not merely ask the model to follow a format and parse the finished text.
| Interface | Expressive power | Typical use |
|---|---|---|
| JSON Schema | Structured JSON objects and arrays | API responses, function arguments |
| Regex | Regular languages | IDs, dates, fixed records |
| { | |
| "1": { | |
| "tab": { | |
| "id": "run", | |
| "label": "Run", | |
| "html": "<!DOCTYPE html>\n<html lang=\"en\">\n<head>\n<meta charset=\"UTF-8\">\n<meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no\">\n<title>Run Pace</title>\n<style>\n html, body { margin: 0; height: 100%; background: #0d1117; color: #c9d1d9;\n font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif; }\n * { box-sizing: border-box; }\n \n .app { display: flex; flex-direction: column; height: 100vh; overflow: hidden; padding: 12px; gap: 8px; }\n \n .header { display: flex; align-items: center; justify-content: space-between; flex-shrink: 0; }\n .header h1 { margin: 0; font-size: 16px; font-weight: 700; display: flex; align-items: center; gap: 6px; }\n .status-dot { width: 10px; height: 10px; border-radius: 50%; display: inline-block; }\n .status-dot.idle { background: #8b949e; }\n .status-dot.running { background: #3fb950; box-shadow: 0 0 12px rg |
| { | |
| "1": { | |
| "tab": { | |
| "id": "paint", | |
| "label": "Paint", | |
| "html": "<!DOCTYPE html>\n<html lang=\"en\">\n<head>\n<meta charset=\"UTF-8\">\n<meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no\">\n<title>Paint</title>\n<style>\n html, body {\n margin: 0; height: 100%;\n background: #0d1117; color: #c9d1d9;\n font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;\n overflow: hidden;\n -webkit-user-select: none; user-select: none;\n }\n #app { display: flex; flex-direction: column; height: 100%; }\n\n /* Top bar */\n header {\n display: flex; align-items: center; gap: 6px;\n padding: 8px 10px;\n background: #161b22; border-bottom: 1px solid #30363d;\n flex-shrink: 0;\n }\n header h1 {\n font-size: 16px; margin: 0 8px 0 0; font-weight: 600; color: #58a6ff;\n flex-shrink: 0;\n }\n .hbtn {\n min-width: 44px; height: 44px;\n display: flex; align-items: center; justify-conte |
| { | |
| "1": { | |
| "tab": { | |
| "id": "jmap-email", | |
| "label": "Email", | |
| "html": "<!DOCTYPE html>\n<html lang=\"en\">\n<head>\n<meta charset=\"UTF-8\">\n<meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0\">\n<title>JMAP Email</title>\n<style>\n html, body { margin: 0; height: 100%; background: #0d1117; color: #c9d1d9;\n font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif; }\n * { box-sizing: border-box; }\n .app { display: flex; flex-direction: column; height: 100%; max-width: 600px; margin: 0 auto; }\n .header { padding: 12px 16px; border-bottom: 1px solid #30363d; background: #161b22;\n display: flex; align-items: center; gap: 8px; min-height: 52px; }\n .header h1 { margin: 0; font-size: 18px; font-weight: 600; flex: 1; white-space: nowrap; overflow: hidden; text-overflow: ellipsis;\n cursor: pointer; -webkit-user-select: none; user-select: none; }\n .header h1:active { opacity: .7; }\n .header .back-btn { background: none; border: none; |
URL: https://gist.github.com/monperrus/6cc2679c5f01fc3d95621e0bb431a91a
Tool under test: ~/bin/ocr-openai.py — OpenAI vision model through the Codex
ChatGPT login (default model gpt-5.4, --detail original).
Determine the maximum number of base64 characters that can be put on an A4 page
| { | |
| "1": { | |
| "tab": { | |
| "id": "piano-tab", | |
| "label": "Piano", | |
| "html": "<!DOCTYPE html>\n<html lang=\"en\">\n<head>\n<meta charset=\"UTF-8\">\n<meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no\">\n<title>Piano Tab - Jazz Manouche</title>\n<script src=\"https://cdnjs.cloudflare.com/ajax/libs/vexflow/4.2.5/vexflow-min.js\"></script>\n<style>\n html, body { margin: 0; height: 100%; overflow: hidden; background: linear-gradient(135deg, #0b0f1a 0%, #0d1117 100%); color: #c9d1d9; font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif; }\n * { box-sizing: border-box; }\n .app { display: flex; flex-direction: column; height: 100dvh; overflow: hidden; }\n .header { padding: 10px 16px 4px; text-align: center; }\n .header h1 { margin: 0; font-size: 16px; background: linear-gradient(135deg, #58a6ff, #79c0ff); -webkit-background-clip: text; -webkit-text-fill-color: transparent; font-weight: 700; }\n .header .sub { font |
| { | |
| "1": { | |
| "tab": { | |
| "id": "jmap-email", | |
| "label": "Email", | |
| "html": "<!DOCTYPE html>\n<html lang=\"en\">\n<head>\n<meta charset=\"UTF-8\">\n<meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0\">\n<title>JMAP Email</title>\n<style>\n html, body { margin: 0; height: 100%; background: #0d1117; color: #c9d1d9;\n font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif; }\n * { box-sizing: border-box; }\n .app { display: flex; flex-direction: column; height: 100%; max-width: 600px; margin: 0 auto; }\n .header { padding: 12px 16px; border-bottom: 1px solid #30363d; background: #161b22;\n display: flex; align-items: center; gap: 8px; min-height: 52px; }\n .header h1 { margin: 0; font-size: 18px; font-weight: 600; flex: 1; white-space: nowrap; overflow: hidden; text-overflow: ellipsis;\n cursor: pointer; -webkit-user-select: none; user-select: none; }\n .header h1:active { opacity: .7; }\n .header .back-btn { background: none; border: none; |
GET https://api.tech.ec.europa.eu/agrifood/api/{series}?beginDate=DD/MM/YYYY&endDate=DD/MM/YYYY
No apiKey, no auth. Verified: pigmeat/prices, cereal/prices, sugar/prices
return weekly/monthly per-member-state price series. milk/prices → 404, i.e. the
series list is narrower than hopeful client code assumes (a public repo's "confirmed"
milk series was confirmed not to exist).