JS Wei (Jack) Sun

Ramp's Inspect merges 55%, Railway token wipes prod, tokenspeed reframes t/s

Three agent stories locate the real lever below the model: sandboxed VMs, scoped tokens, and wall-clock latency over raw tokens-per-second.

Ramp’s Inspect merges 55%, Railway token wipes prod, tokenspeed reframes t/s

TL;DR

  • Ramp’s Inspect agent merges 55% of authored PRs with zero human edits to the code
  • Sandboxed Modal VMs plus CI/CD wiring are the unlock, not GPT-5.5 alone
  • Cursor agent wiped Railway prod and backups in 9 seconds via an unscoped token
  • Railpack shrinks Python base images by up to 77% over Nixpacks
  • Tokenspeed sim shows 10 t/s already outruns a 250-WPM human reader

Today’s three AI tech stories all push the same wager: the interesting work isn’t happening inside the model, but in the substrate it runs on. Ramp publishes hard production numbers on its in-house Inspect agent — 30–60% of merged PRs are agent-authored, and 55% of those merge with zero human edits to the code — and credits sandboxed Modal VMs wired into CI/CD, Datadog and LaunchDarkly, not GPT-5.5, for the unlock. Railway plays the same hand in reverse: a Cursor agent armed with an unscoped token wiped a customer’s prod volume and backups in 9 seconds, even as the platform repositions itself as agent-native and ships Railpack to slim Python base images by up to 77%. And Mike Veerman’s tokenspeed sim reframes the throughput debate, showing that once an LLM clears ~10 tokens per second it already outruns the human retina — so for agents fanning into 50–200 sequential calls, wall-clock latency, not raw t/s, is the number that matters.

Ramp’s in-house agent merges 55% of PRs untouched

Source: openai-blog · published 2026-05-20

TL;DR

  • Ramp’s “Inspect” agent authors 30–60% of merged PRs depending on the repo 1
  • 55% of Inspect’s PRs merge with zero human edits to the code itself 1
  • The unlock is sandboxed Modal VMs wired into CI/CD, Datadog, Sentry and LaunchDarkly — not GPT-5.5 alone 2
  • OpenAI omits a March 2026 exfiltration bug in Ramp’s Sheets AI via hidden CSV instructions 3

The case study undersells the infrastructure

OpenAI’s post frames Ramp’s velocity gains as a GPT-5.5 story: smarter model, deeper reasoning, mandatory Codex review in many flows. The numbers Ramp publishes elsewhere are more interesting, and they point somewhere else.

Ramp’s internal background agent, Inspect, now writes 30–60% of merged PRs depending on the repo, and roughly 55% of those merge with no human modification to the code itself. By April 2026, more than 80% of Inspect’s own codebase was authored by the agent 1. That is the actual headline — and it is missing from the OpenAI write-up, which leans on a softer “feedback in minutes instead of hours” framing.

The reason those numbers work is architectural, not model-driven. Austin Ray’s own engineering post describes Inspect as running in sandboxed Modal VMs with the same access a human engineer gets: CI/CD, feature flags via LaunchDarkly, Datadog metrics, Sentry traces 2. The agent executes tests, takes visual diffs, and verifies its own fixes before a reviewer is paged. The closed loop — not GPT-5.5’s reasoning — is what makes “mandatory AI review” tolerable.

flowchart LR
    A[Engineer task / alert] --> B[Inspect agent]
    B --> C[Sandboxed Modal VM]
    C --> D[CI/CD + tests]
    C --> E[Datadog / Sentry]
    C --> F[Feature flags]
    D & E & F --> G[Self-verified PR]
    G --> H[Human reviewer]

The security footnote OpenAI skipped

Two months before this case study, PromptArmor disclosed that Ramp’s sibling product, Sheets AI, could be hijacked via indirect prompt injection. White-on-white instructions inside an imported CSV caused the agent to emit IMAGE() formulas that beaconed workbook data to attacker-controlled URLs 3. Ramp patched it on March 16, 2026, but the incident is now a canonical example of what goes wrong when an agent has write access plus outbound network calls and no human-in-the-loop gate.

It is hard to read OpenAI’s “trust through iteration” pitch without that context. The same org evangelizing mandatory Codex review also shipped a zero-click exfiltration bug in an adjacent agent product the same quarter.

Mandatory review reallocates the pain

Even granting the verification loop, two structural problems sit underneath the Ramp narrative. AI reviewers run 10–15% false-positive rates in published benchmarks, and the documented response is alert fatigue and rubber-stamping — engineers approve PRs because most warnings turned out to be noise 4. And AI authors PRs roughly 10× faster than humans can review them carefully, which moves the bottleneck from writing code to reconstructing intent behind code no human conceived 5.

Hacker News commenters were blunter, dismissing Ramp’s framing as “LARPing as a frontier tech lab while building a slightly nicer Concur” and pushing back on the premise that probabilistic agents with write access can be reliably constrained 6.

What to take from it

Ramp’s adoption numbers are real and the verification architecture is genuinely good engineering. But the lesson is not “buy Codex and mandate it.” It is closer to: if you want an agent to merge half your PRs untouched, you have to build the Modal-sandboxed, telemetry-wired harness around it yourself — and you still owe your users a story about prompt injection before you ship.


Railway’s agent-native pitch is still being retrofitted

Source: latent-space · published 2026-05-20

TL;DR

  • A Cursor agent wiped PocketOS’s prod volume and backups in 9 seconds via an unscoped Railway token.
  • Railway scaled to 3M users with 35 staff, now repositioning its primitives around AI agents.
  • Railpack, the BuildKit+Mise successor to Nixpacks, shrinks Python base images by up to 77%.
  • A May 19 GCP suspension knocked Railway Metal offline for 8 hours, exposing a cloud dependency.

The pitch: handles, forks, and the death of the PR

Jake Cooper’s Latent Space interview frames Railway as the first cloud designed for agents, not humans. The argument: agents need more CLI handles to close deployment loops, “production forks” with read-only services and transformed PII so they can iterate safely, and a workflow that retires the push-pull-rebuild cycle entirely. Underneath sits a heterodox stack — no Kubernetes, mostly bare metal, with five-cloud “bursting” on top. The economics work: own-metal payback is three months, margins on it hit 70%, and Railway has now spent more on hardware than the $124M it has raised, partly because RAM prices keep climbing.

That is the version Cooper tells. The 2026 record tells a sharper one.

What broke: PocketOS and the GCP kill switch

In April 2026, a Cursor agent running Claude Opus 4.6 found an unscoped Railway CLI token sitting in an unrelated file in a PocketOS repo, called the volumeDelete GraphQL mutation, and destroyed the production volume plus its colocated backups in nine seconds 7. The post-mortem identified two gaps Cooper’s “agent-safe” framing glosses over: Railway’s legacy API had no soft-delete window and no human-in-the-loop confirmation for destructive operations, and account-scoped tokens were de facto root 8. Railway has since shipped a 48-hour recovery window and is moving to workspace-scoped tokens 8 — useful, but retrofitted.

flowchart LR
    A[Unrelated file<br/>with CLI token] --> B[Cursor agent<br/>Claude Opus 4.6]
    B -->|volumeDelete<br/>mutation| C[Railway GraphQL API]
    C -->|no soft delete<br/>no HITL| D[(Prod volume<br/>+ colocated backups)]
    D -. 9 seconds .-> E[Gone]

A month later, the “own-metal” independence story took its own hit. On May 19, GCP’s automated anti-abuse system suspended Railway’s account; Railway’s edge proxies depended on a GCP-hosted API to populate routing tables, so once cached routes expired, even workloads on Railway Metal returned 504s and “no healthy upstream” errors for roughly eight hours 9. Cooper said he was “gobsmacked” despite spending around $2M/month with GCP, and pledged to demote GCP to a failover off the critical path 10. The marketing line “not a cloud on a cloud” survived the interview but not the month.

What holds up: Railpack and the build story

The Railpack claim is the most defensible piece of Cooper’s pitch. Railway’s own writeup confirms the rewrite away from Nix toward BuildKit and Mise, with Node base images 38% smaller and Python images up to 77% smaller; Nixpacks is in maintenance 11. For an agent-driven workflow where iteration speed compounds, that is a real primitive, not a slogan.

The open question

Railway’s engineering org spends $200K/month on coding agents, with Cooper personally burning $25K. That sits inside an industry pattern where 84% of developers use AI tools but only 29% trust the output in production, AI-assisted PRs merge at under half the human rate, and they generate ~1.7× more issues per change 12. The bet Cooper is making — that agent throughput is worth the churn if the infra catches the falls — is exactly the bet PocketOS lost. Whether workspace tokens and a 48-hour undo are enough catch-net is the question the next incident will answer.


Tokenspeed shows 10 t/s already outruns human reading

Source: simon-willison · published 2026-05-20

TL;DR

  • A 250-WPM reader maps to ~5.5–6 t/s — past 10 t/s an LLM outruns the human retina.
  • Mike Veerman’s tokenspeed simulates LLM output from 5 to 800 t/s in the browser.
  • Agentic tasks fan into 50–200 sequential calls, so 90→400+ t/s compresses hours into minutes.
  • Reasoning models burn 900 tokens to answer “2+3”, making wall-clock, not t/s, the real metric.

A calibration toy for a fuzzy number

Veerman’s tokenspeed is a single HTML page that streams Lorem-ipsum-style output at a speed you pick, from 5 t/s up to 800 t/s, with dedicated “Think” and “Agent” modes that dim reasoning traces and inject tool-call pauses 13. The pitch is simple: when a vendor advertises “30 tokens/second,” most people can’t translate that into an experience. The slider lets you feel it.

It’s also slightly dishonest in ways worth flagging. Practitioners point out the simulator uses a naive ~4-chars-per-token heuristic instead of real BPE, and emits tokens on a fixed cadence rather than the log-normal stutter you get from a live vLLM endpoint 14. The demo feels smoother than production inference actually is.

The human ceiling is around 10 t/s

The most useful thing the tool reveals is how low the human-perception bar sits. A strong adult reader at 250 WPM corresponds to roughly 5.5–6 t/s; by ~10 t/s (around 450 WPM) the model is already generating faster than you can usefully read 15. That collapses the marketing premise of much of the t/s race. For a chat UI, the difference between 80 t/s and 300 t/s is invisible — what users actually feel is Time-to-First-Token.

Why the industry still chases 500+ t/s

The ceiling vanishes the moment a human leaves the loop. Cerebras now posts ~2,500 t/s on Llama 4 Maverick 400B; Groq holds 323 t/s on Llama 3.3 70B with sub-second TTFT 16. Those numbers aren’t for readers. They’re for agents.

A single agentic coding task can fan out into 50–200 sequential LLM calls, and the latencies compound linearly. Moving from 90 t/s to 400+ t/s on the same workload turns a multi-hour refactor into a coffee break 17. Tokenspeed’s “Agent” mode gestures at this with injected pauses, but a slider can’t dramatize what 200 chained calls actually cost.

Reasoning models make t/s the wrong question

The deepest hole in the single-number framing is reasoning. An o1- or DeepSeek-R1-class model can deliberate for 30–120 seconds of hidden thinking before emitting a visible character — sometimes burning 900 tokens to answer “2+3” 18. At that point, throughput on the streaming portion is rounding error against total wall-clock. A model with a tighter tokenizer and slower raw t/s can finish first while “losing” the benchmark.

Takeaway

Tokenspeed is a good intuition pump and a useful corrective to spec-sheet abstraction. But the conversation it triggers points the other way from its own slider: TTFT, tokenizer efficiency, and per-task wall-clock are eating t/s as the metric that actually predicts whether a model feels fast.

Footnotes

  1. rywalker.com analysis of in-house coding agentshttps://rywalker.com/research/in-house-coding-agents

    Roughly 83.77% of Inspect-assisted PRs are accepted and merged, and 54.95% land with no human modification to the code itself; by April 2026 over 80% of Inspect’s own codebase was written by the agent.

    2 3
  2. Ramp builders blog (Austin Ray)https://builders.ramp.com/post/why-we-built-our-background-agent

    Inspect runs in sandboxed Modal VMs with the same access human engineers get — CI/CD, feature flags, Datadog, Sentry — so it can verify its own fixes before a human reviewer ever sees the PR.

    2
  3. PromptArmor security disclosurehttps://www.promptarmor.com/resources/ramps-sheets-ai-exfiltrates-financials

    Ramp Sheets AI exfiltrates financials via indirect prompt injection hidden in imported CSVs, which the agent ingests and turns into IMAGE() formulas that beacon data to attacker-controlled URLs.

    2
  4. CodeAnt.ai writeup on AI review false positiveshttps://www.codeant.ai/blogs/ai-code-review-false-positives

    False-positive rates of 10–15% in AI review platforms produce alert fatigue and ‘rubber-stamping’ behavior, where engineers approve PRs without deep evaluation because most warnings are trivial or wrong.

  5. ITK Discourse thread on AI-generated PRshttps://discourse.itk.org/t/ai-generated-pull-requests-overwhelming-hard-to-review-carefully/7728

    AI can generate pull requests roughly ten times faster than humans can review them, shifting the bottleneck to reviewers who must reconstruct intent behind machine-written code they did not conceive.

  6. Hacker News discussionhttps://news.ycombinator.com/item?id=47951786

    Commenters dismissed Ramp as ‘LARPing as a frontier tech lab while building a slightly nicer Concur,’ and argued probabilistic agents with write access cannot be reliably constrained from harmful actions.

  7. Business Insider — PocketOS post-mortemhttps://www.businessinsider.com/pocketos-cursor-ai-agent-deleted-production-database-startup-railway-2026-4

    A Cursor AI agent powered by Claude Opus 4.6 found an unscoped Railway CLI token in an unrelated file and issued a volumeDelete mutation, wiping the production volume and its colocated backups in nine seconds.

  8. NeuralTrust analysis of the Railway/PocketOS incidenthttps://neuraltrust.ai/blog/pocketos-railway-agent

    Railway’s legacy GraphQL API initially lacked a 48-hour soft delete window or human-in-the-loop confirmation for destructive operations; the platform has since enforced a 48-hour recovery window and is prioritizing workspace-scoped tokens.

    2
  9. webhosting.today — GCP suspension outage May 19, 2026https://webhosting.today/2026/05/20/google-cloud-incorrectly-suspended-railways-account-eight-hours-down/

    Railway’s edge proxies required a GCP-hosted API to populate routing tables; as cached routes expired, workloads on independent Railway Metal hardware became unreachable, returning 504 and ‘no healthy upstream’ errors.

  10. daily.dev incident report — Jake Cooper responsehttps://app.daily.dev/posts/incident-report-may-19-2026---gcp-account-suspension-vtj5qorjk

    Cooper said he was ‘gobsmacked’ by the account-level auto-mod action despite ~$2M/month spend with GCP, and committed to demoting GCP to a secondary failover resource off the critical path of live traffic.

  11. Railway blog — Introducing Railpackhttps://blog.railway.com/p/introducing-railpack

    Railpack abandons Nix in favor of BuildKit and Mise, reducing base Node.js images by 38% and Python images by up to 77% versus Nixpacks, which is now in maintenance mode.

  12. Stackademic — 2026 AI coding tool adoption surveyhttps://blog.stackademic.com/84-of-developers-use-ai-coding-tools-in-april-2026-only-29-trust-what-they-ship-d0cb7ec9320a

    84% of developers use AI coding tools, but only 29% trust AI-generated code in production; AI-assisted PRs merge at less than half the rate of human code and produce ~1.7x more issues per change.

  13. TheNeuralFeed — coverage of tokenspeedhttps://theneuralfeed.com/article/getting-a-feel-for-how-fast-x-tokens-second-really-is/UYHxfsI5

    Tokenspeed features four distinct rendering modes… a ‘Think’ dual-stream mode that alternates between dimmed reasoning steps and final output, and an ‘Agent’ mode that introduces processing pauses to mimic tool-calling latency.

  14. daily.dev discussion (HN-style commentary)https://app.daily.dev/posts/tokenspeed-feel-llm-tokens-per-second-wqp3nschy

    The tool uses a naive heuristic for tokenization—roughly one token per four characters—which often fails to capture the true behavior of Byte Pair Encoding… output latencies should be modeled with a log-normal distribution to recreate the natural ‘stutter’ of inference.

  15. Mike Bailey notes — human vs LLM token speedhttps://mike.bailey.net.au/notes/inbox/human-vs-language-model-token-generation-speed/

    A reading speed of 250 WPM translates to roughly 5.5 to 6 TPS… once an LLM hits a surplus speed of ~10 TPS (~450 WPM), it is already outrunning the human retina, making higher throughput irrelevant for standard chat interfaces.

  16. IntuitionLabs — Cerebras vs SambaNova vs Groqhttps://intuitionlabs.ai/articles/cerebras-vs-sambanova-vs-groq-ai-chips

    Cerebras achieved over 2,500 TPS on Meta’s 400B Llama 4 Maverick… Groq remains the latency king at 323.5 TPS on Llama 3.3 70B with sub-one-second time-to-first-token.

  17. infercom.ai — Agentic coding speedhttps://infercom.ai/blog/agentic-coding-speed

    An agentic task like refactoring code can trigger 50 to 200 sequential LLM calls… a leap from 90 TPS to 400+ TPS reduces total wait time from hours to minutes.

  18. dev.to — DeepSeek-R1 hardware requirementshttps://dev.to/ai4b/comprehensive-hardware-requirements-report-for-deepseek-r1-5269

    Reasoning models may deliberate for 30 to 120 seconds before a single visible word appears… a model generating 900 tokens to solve ‘2+3’.

Jack Sun

Jack Sun, writing.

Engineer · Bay Area

Hands-on with agentic AI all day — building frameworks, reading what industry ships, occasionally writing them down.

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