bab66bb226
Dogfooded 2026-04-18 on main HEAD d0de86e from /tmp/cdE. MCP
command, args, url, headers, headersHelper config fields are
loaded and passed to execve/URL-parse verbatim. No ${VAR}
interpolation, no ~/ home expansion, no preflight check, no doctor
warning.
Repros:
- {'command':'~/bin/my-server','args':['~/config/file.json']} ->
execve('~/bin/my-server', ['~/config/file.json']) -> ENOENT at
MCP connect time.
- {'command':'${HOME}/bin/my-server','args':['--tenant=${TENANT_ID}']}
-> literal ${HOME}/bin/my-server handed to execve; literal
${TENANT_ID} passed to the server as tenant argument.
- {'headers':{'Authorization':'Bearer ${API_TOKEN}'}} -> literal
string 'Bearer ${API_TOKEN}' sent as HTTP header.
Trace: parse_mcp_server_config in runtime/src/config.rs stores
strings raw; McpStdioProcess::spawn at mcp_stdio.rs:1150-1170 is
Command::new(&transport.command).args(&transport.args).spawn().
grep interpolate/expand_env/substitute/${ across runtime/src/
returns empty outside format-string literals.
Clawability impact: every public MCP server README uses ${VAR}/~/
in examples; copy-pasted configs load with doctor:ok and fail
opaquely at spawn with generic ENOENT that has lost the context
about why. Operators forced to hardcode secrets in .claw.json
(triggering #90) or wrap commands in shell scripts -- both worse
security postures than the ecosystem norm. Cross-harness round-trip
from Claude Code /.mcp.json breaks when interpolation is present.
Fix shape (~50 lines): config-load-time interpolation of ${VAR}
and leading ~/ in command/args/url/headers/headers_helper; missing-
variable warnings captured into ConfigLoader all_warnings; optional
{'config':{'expand_env':false}} toggle; mcp_config_interpolation
doctor check that flags literal ${ / ~/ remaining after substitution.
Filed in response to Clawhip pinpoint nudge 1494721628917989417 in
#clawcode-building-in-public.
Claw Code
ultraworkers/claw-code · Usage · Rust workspace · Parity · Roadmap · UltraWorkers Discord
Claw Code is the public Rust implementation of the claw CLI agent harness.
The canonical implementation lives in rust/, and the current source of truth for this repository is ultraworkers/claw-code.
Important
Start with
USAGE.mdfor build, auth, CLI, session, and parity-harness workflows. Makeclaw doctoryour first health check after building, userust/README.mdfor crate-level details, readPARITY.mdfor the current Rust-port checkpoint, and seedocs/container.mdfor the container-first workflow.ACP / Zed status:
claw-codedoes not ship an ACP/Zed daemon entrypoint yet. Runclaw acp(orclaw --acp) for the current status instead of guessing from source layout;claw acp serveis currently a discoverability alias only, and real ACP support remains tracked separately inROADMAP.md.
Current repository shape
rust/— canonical Rust workspace and theclawCLI binaryUSAGE.md— task-oriented usage guide for the current product surfacePARITY.md— Rust-port parity status and migration notesROADMAP.md— active roadmap and cleanup backlogPHILOSOPHY.md— project intent and system-design framingsrc/+tests/— companion Python/reference workspace and audit helpers; not the primary runtime surface
Quick start
Note
[!WARNING]
cargo install claw-codeinstalls the wrong thing. Theclaw-codecrate on crates.io is a deprecated stub that placesclaw-code-deprecated.exe— notclaw. Running it only prints"claw-code has been renamed to agent-code". Do not usecargo install claw-code. Either build from source (this repo) or install the upstream binary:cargo install agent-code # upstream binary — installs 'agent.exe' (Windows) / 'agent' (Unix), NOT 'agent-code'This repo (
ultraworkers/claw-code) is build-from-source only — follow the steps below.
# 1. Clone and build
git clone https://github.com/ultraworkers/claw-code
cd claw-code/rust
cargo build --workspace
# 2. Set your API key (Anthropic API key — not a Claude subscription)
export ANTHROPIC_API_KEY="sk-ant-..."
# 3. Verify everything is wired correctly
./target/debug/claw doctor
# 4. Run a prompt
./target/debug/claw prompt "say hello"
Note
Windows (PowerShell): the binary is
claw.exe, notclaw. Use.\target\debug\claw.exeor runcargo run -- prompt "say hello"to skip the path lookup.
Windows setup
PowerShell is a supported Windows path. Use whichever shell works for you. The common onboarding issues on Windows are:
- Install Rust first — download from https://rustup.rs/ and run the installer. Close and reopen your terminal when it finishes.
- Verify Rust is on PATH:
If this fails, reopen your terminal or run the PATH setup from the Rust installer output, then retry.cargo --version - Clone and build (works in PowerShell, Git Bash, or WSL):
git clone https://github.com/ultraworkers/claw-code cd claw-code/rust cargo build --workspace - Run (PowerShell — note
.exeand backslash):$env:ANTHROPIC_API_KEY = "sk-ant-..." .\target\debug\claw.exe prompt "say hello"
Git Bash / WSL are optional alternatives, not requirements. If you prefer bash-style paths (/c/Users/you/... instead of C:\Users\you\...), Git Bash (ships with Git for Windows) works well. In Git Bash, the MINGW64 prompt is expected and normal — not a broken install.
Note
Auth: claw requires an API key (
ANTHROPIC_API_KEY,OPENAI_API_KEY, etc.) — Claude subscription login is not a supported auth path.
Run the workspace test suite:
cd rust
cargo test --workspace
Documentation map
USAGE.md— quick commands, auth, sessions, config, parity harnessrust/README.md— crate map, CLI surface, features, workspace layoutPARITY.md— parity status for the Rust portrust/MOCK_PARITY_HARNESS.md— deterministic mock-service harness detailsROADMAP.md— active roadmap and open cleanup workPHILOSOPHY.md— why the project exists and how it is operated
Ecosystem
Claw Code is built in the open alongside the broader UltraWorkers toolchain:
Ownership / affiliation disclaimer
- This repository does not claim ownership of the original Claude Code source material.
- This repository is not affiliated with, endorsed by, or maintained by Anthropic.