Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/midstall/claude-for-hardware/codegen-validationnpx skills add Midstall/claude-for-hardware --skill codegen-validationgit clone --depth 1 https://github.com/Midstall/claude-for-hardwareWhat it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00046 | $0.00891 |
| Opus 5 | $0.00023 | $0.00445 |
| Sonnet 5 | $0.00009 | $0.00178 |
| Haiku 4.5 | $0.00005 | $0.00089 |
Grade A, and why
codegen-validation scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 74 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Codegen Validation
Overview
A codegen backend is correct when the code it emits computes the right answer on a real machine. Reading the assembly proves nothing; a plausible-looking instruction sequence with a wrong ABI detail or a clobbered callee-saved register passes every eyeball review and fails on hardware.
Core principle: Execution-validate. Compile a known program, run the output on a real CPU or a fast emulator, and assert the observed result. If you didn't run it, you don't know it works.
When to Use
- Bringing up a new codegen target or instruction selection
- Implementing calling conventions, stack frames, register spilling, relocations
- Debugging "the assembly looks right but the answer is wrong"
- Adding an optimization pass and needing to prove it preserves behavior
The Validation Loop
known program (expected result known)
-> codegen -> machine code
-> run on real CPU / fast emulator
-> assert observed result == expected
- Pick programs with known answers. Start tiny: return a constant, add two args, a call to a leaf function, a loop that sums. Each isolates one capability (literals, ABI, calls, control flow).
- Run on something real and fast. A native emulator for your target CPU closes the loop in milliseconds, so it can run on every build. The point is real execution semantics, not a model of what you think the instruction does.
- Assert the observed value, not "it didn't crash." Read the result register or memory and compare to the expected answer.
This Catches Bugs Review Misses
Execution validation reliably catches the codegen bugs that look fine on paper:
- A
select/conditional-move lowering that picks the wrong operand. - Critical-edge splitting that drops or duplicates a value.
- A prologue/epilogue that fails to save/restore a callee-saved register (return-address corruption shows up only when something actually calls).
- ABI mistakes: argument in the wrong register, stack misaligned, return value in the wrong place.
- Relocations that resolve to the wrong address.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2d ago First seen · 74 lines · 46 tokens per session scan A 71656d328d04
codegen-validation is a skill published in the GitHub repository Midstall/claude-for-hardware (18 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 46 tokens to every session and 891 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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