fpga-fit

fpga-fit is a command for Claude Code from Midstall/claude-for-hardware. It costs 16 tokens per session (371 once invoked), scanned A, original, Apache-2.0.

A command workflow for fitting digital hardware written in RTL onto an FPGA and meeting its timing limits. RTL is code describing hardware circuits, while timing is whether signals arrive quickly enough for the design's clock.

In plain words
What is it for?
Use it to reduce FPGA resource use, fix designs that do not route, improve slow paths, try placement seeds, and check for inefficient memory implementations.
Why use it?
It replaces guesses about size and speed with measurements from synthesis, placement, routing, and critical-path reports.

Command for Claude Code

Written for Claude Code: argument-hint in frontmatter.

Part of the claude-for-hardware plugin — 14 skills, 3 commands, 3 agents, 1 hook shipped together

Good fit Use it to reduce FPGA resource use, fix designs that do not route, improve slow paths, try placement seeds, and check for inefficient memory implementations.

Compare 6 commands from other repositories ↓
Install with agentmods
npx agentmods add commands/midstall/claude-for-hardware/fpga-fit
Install

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.

Clone the repo
git clone --depth 1 https://github.com/Midstall/claude-for-hardware

Made for: Claude Code.

Or install claude-for-hardware, the plugin that ships this one along with the rest of its 14 skills, 3 commands, 3 agents, 1 hook.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for fpga-fit

README.md
[![agentmods](https://agentmods.dev/badge/commands/midstall/claude-for-hardware/fpga-fit/github.svg)](https://agentmods.dev/commands/midstall/claude-for-hardware/fpga-fit)
Your own site
<a href="https://agentmods.dev/commands/midstall/claude-for-hardware/fpga-fit"><img src="https://agentmods.dev/badge/commands/midstall/claude-for-hardware/fpga-fit/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for fpga-fit

Your own site · 80×15
<a href="https://agentmods.dev/commands/midstall/claude-for-hardware/fpga-fit"><img src="https://agentmods.dev/badge/commands/midstall/claude-for-hardware/fpga-fit.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 16 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 371 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00016 $0.00371
Opus 5 $0.00008 $0.00186
Sonnet 5 $0.00003 $0.00074
Haiku 4.5 $0.00002 $0.00037

Measured 9d ago against content hash 48e4ce0a1d28, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

fpga-fit 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 9d 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.

commands/fpga-fit.md · 17 lines

What it actually says

The user wants to fit an RTL design onto an FPGA, hit timing, or fix a route that will not converge. Context they gave: $ARGUMENTS

Invoke the fpga-synthesis-fit skill, and rtl-area-timing if the bottleneck is a structure (a wide multiply, a barrel shifter, a compute-everything-and-select datapath). Then drive this loop, one measured step at a time:

  1. Measure with the right number. Read post-pack nextpnr TRELLIS_COMB (or the equivalent post-place utilization), never the pre-pack synth LUT count. For timing, read the critical-path report and name the specific primitive on it.
  2. If it will not route: try other seeds before changing RTL, watch the overused-wire count trend toward zero, and keep utilization under the thrash threshold (roughly 85 percent, and BRAM under 90).
  3. If it is too big or too slow: apply one structural change from rtl-area-timing (internal multiply pipeline, dead-arm removal, resource sharing, fixed-slice mux), then re-measure post-pack. Stop optimizing a resource once it leaves the critical path.
  4. Check for the flop-ROM trap: a "ROM" with per-entry reset values becomes a huge flop array. Instantiate block RAM with init instead.
  5. If you generate a bring-up bitstream, confirm its configured clock is at or below the measured Fmax.

Report each step's measurement and the one change you made, not a batch of speculative edits. Do not claim a win without a post-pack number.

Changes

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.

  1. 9d ago First seen · 17 lines · 16 tokens per session scan A 48e4ce0a1d28

Subscribe to this mod's changes

fpga-fit is a command published in the GitHub repository Midstall/claude-for-hardware (20 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 16 tokens to every session and 371 once invoked, about $0.0001 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.