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A letter from Repath KhanSeptember 2026

AI writes the code. Critique makes it reviewable.

Dear Investors.

This is a letter from one engineer about the layer I think the agent era forgot to build: the one that makes machine-generated code safe to trust, cheap to review and possible for humans to continue owning. Skim the section eyebrows, jump to what matters, skip the rest. My email is at the top and again at the bottom.

Category

Independent review for agent-written code

Posture

Claims are claims, not evidence

Stage

Working system, raising runway

Metric

Correct understanding per minute of human attention

The bet

AI is making code cheap. Understanding, trust and ownership are becoming the scarce resources.

Critique is being built as the infrastructure for that gap: the layer between coding agents and production software.

Interactive read

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Documentation and ship logs

We publish architecture notes beside the product. If you want the same mental model our engineers use for webhooks, queues, models, memory, Remedy, and credits, start with the docs, then read the founder posts for narrative and release cadence.

Product docs

Default docs entry: Memory system overview. Marketing site: critique.sh, Builder: /workspace?mode=build, Remedy: /remedy, Ship log: /version.

01The asymmetry

Agents now produce code much faster than we can properly understand it.

Over the last year, I have spent a lot of time building and working with coding agents. Somewhere along the way, I realised the thing that worries me most about them is also the thing that makes them so powerful: they can now produce code much faster than we can properly understand it.

A good coding agent can make a large change across a repository in minutes. It can add tests, refactor files, update APIs and confidently tell you everything works. The problem is that someone still has to decide whether that change actually belongs in production.

That part has not become 10x faster.

We still review code at roughly human speed. We still need to understand how a change interacts with the rest of the system. We still need to notice when an implementation is locally correct but architecturally wrong, when an agent made a subtle assumption, or when a test proves much less than the agent claims it does.

I think this is becoming one of the most important problems in software engineering.

The asymmetry, visualised
Writing codeMinutes

A good agent lands a large, cross-repo change with tests before coffee.

Understanding itHuman speed

Review still runs at reading speed. That part has not become 10x faster.

“The industry has spent enormous amounts of money making agents better at writing code. The next problem is making machine-generated code safe to trust, cheap to review and possible for humans to continue owning.”
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02The product

Critique sits beside coding agents and independently reviews the work they produce.

Critique started as an AI code reviewer, but it has gradually become something more specific. It sits beside coding agents like Claude Code, Codex, Cursor or our own CritiqueCode and independently reviews the work they produce.

The important word is independently.

Critique does not simply ask the coding agent whether it finished correctly. When a review starts, the reviewer can be given the task and the repository without receiving the author’s conversation, confidence, worklog or claimed test results. I deliberately built that separation because otherwise the reviewer begins from the same assumptions as the agent that wrote the code.

Critique treats the author’s claims as claims, not evidence.

If an agent says it fixed a race condition, Critique can investigate whether that failure actually existed and whether the new code really prevents it. It can run controlled checks, inspect callers and dependencies, trace the surrounding system, route security-sensitive changes through deeper review, and distinguish between something a model merely suspects and something that has actually been reproduced or supported by evidence.

Claims vs evidence

The reviewer starts without the author's conversation, confidence, worklog or claimed test results. Otherwise it begins from the same assumptions as the agent that wrote the code.

  • Author claim

    “I fixed the race condition.”

    Critique asks

    Did the failure actually exist, and does the new code really prevent it?

  • Author claim

    “All tests pass.”

    Critique asks

    Does the suite cover the changed path, or prove much less than claimed?

  • Author claim

    “The refactor is behaviour-preserving.”

    Critique asks

    Callers, contracts and dependencies traced, not taken on confidence.

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03Verified repair

A repair is not successful because the fixing agent says it worked.

The same principle applies to repairs. If Critique finds a defect and an agent attempts to fix it, that repair should not be considered successful simply because the fixing agent says it worked. Critique can verify the repair independently before allowing it back into the workflow.

I have also been building a broader change-control layer around this. Critique can track the provenance and risk of a change, attach review evidence to it, apply merge policy and preserve proof of verified repairs.

The eventual question is not just “what comments did the AI reviewer leave?” It is “what do we actually know about this change, and should it be allowed to ship?”

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04The bigger problem

We give machines a detailed map of the repository. Then the human reviewer still gets a diff.

While building all of this, I noticed another problem that I now think may be even larger.

Critique already builds a surprisingly detailed understanding of a repository for its own reviewers. It can map symbols, callers, callees, tests, dependency relationships and changed public interfaces. It can work out which parts of a codebase sit in the blast radius of a change.

We give all of that context to machines.

Then the human reviewer still gets a diff.

That feels backwards.

If an agent produces a 3,000-line change, the answer cannot be to ask a human to read faster. The system should instead tell them what changed behaviourally, where it propagates, which assumptions matter, what has already been proven and which decisions still genuinely require human judgement.

“Not another long AI-generated PR summary. A structured, evidence-backed map of the change.”
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05Where Critique goes next

A structured, evidence-backed map of the change, built for human judgement.

That is where I want to take Critique next.

I want a reviewer to open a change and quickly understand: this touched authentication, these seven callers depend on it, these tests cover the changed path, this behaviour was reproduced before the fix, this part remains uncertain, and these two architectural decisions still need a human.

The metric I care about is not how many comments Critique can generate. It is how much correct understanding a human can acquire per minute of attention.

I think this becomes increasingly valuable as coding agents improve. Better agents do not remove the review problem. They create more plausible code, more quickly. And plausible code is precisely the code that is hardest to reject casually.

change-map · PR #1402
  • Area touchedAuthentication
  • Dependent callers7 callers depend on this path
  • CoverageChanged path covered by existing tests
  • ReproductionFailure reproduced before the fix
  • UncertaintyOne path remains unproven
  • Human judgement2 architectural decisions need a person
Illustrative. The point: not another long AI-generated PR summary, but a structured, evidence-backed map of the change, so human attention lands only where judgement is actually required.
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06The raise

I am raising because I want to work on this full time.

There is already a real system behind the idea: a local reviewer CLI, an independent review and evidence runtime, repository intelligence, verified repair, change-control infrastructure, and CritiqueCode, our own coding agent that uses the same review machinery. I am also working on a hosted version of CritiqueCode so the entire author, review, repair, ship loop can happen from the browser.

What I need now is focused runway to turn those pieces into the product I think should exist between coding agents and production software.

If you invest in developer infrastructure, AI systems or the future of software engineering, I would love to talk.

Already built

This is not a slideware raise. The pieces below exist and run today; the round turns them into one product between coding agents and production.

  • Reviewer CLILocal independent review, runnable beside any coding agent.
  • Evidence runtimeControlled checks that reproduce or refute author claims.
  • Repository intelligenceSymbols, callers, tests, dependencies, blast radius.
  • Verified repairFixes re-verified independently before they re-enter the workflow.
  • CritiqueCodeOur own coding agent, forced through the same review machinery.
  • Hosted CritiqueCodeAuthor, review, repair, ship, entirely from the browser.
“My bet is simple: AI is making code cheap. Understanding, trust and ownership are becoming the scarce resources.”
6
Working system pieces already built: reviewer CLI, evidence runtime, repository intelligence, verified repair, change control, CritiqueCode
1
Loop being unified: author, review, repair, ship, from the browser
Independent
Review posture: the author’s claims are treated as claims, not evidence
Per minute
The metric that matters: correct human understanding acquired per minute of attention
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Connect
ray@critique.sh

Investors in developer infrastructure, AI systems, or the future of software engineering: write directly. A short note beats a perfect one.

LinkedIn
Repath Khan on LinkedIn
Background, prior work, people I have worked with

Book fifteen minutes

No deck, no warm-up. I can walk you through the reviewer, the evidence runtime, and one real independent review inside fifteen minutes.

Open for conversations

If you invest in developer infrastructure, AI systems or the future of software engineering, I would love to talk.

The loop between coding agents and production software is where I am spending the decade. If that gap sits inside your fund thesis, reply with capital appetite and a diligence outline.

AI writes the code. Critique makes it reviewable.

Written in the open, shipped the same day it was drafted.

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