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[feature] harness prompt delivery: stdin / embedded placeholders and verified invoke templates #27
Description
Summary
Split from #9 (items 5–6 of its suggested fixes). After #9, a harness is probed with a bounded deadline and is only dispatchable with an invoke_args_template. But the template still can't pass the prompt the way real CLIs expect it, so live dispatch of claude, codex, grok, pi and agy still needs a wrapper script per harness.
Problem
CliHarness::invoke (crates/meshloop-adapters/src/harness.rs):
- substitutes
{prompt_file}only when it is a whole argument (no--prompt-file={prompt_file}); - has no way to pass the prompt text (
{prompt}), whichclaude -p "<prompt>"andcodex exec "<prompt>"expect; - always uses
stdin(Stdio::null()), so CLIs that read the prompt from stdin cannot be used.
Proposed scope
- A config option such as
prompt_via = "stdin" | "arg" | "file"(defaultfilekeeps current behaviour). - Embedded placeholder substitution inside arguments (
"--prompt-file={prompt_file}"). - Decide whether a
{prompt}text placeholder is acceptable (argv length limits on Windows ~32 KiB; quoting; secrets in process listings). Stdin may be the safer default. - Per-harness
invoke_args_templateexamples inconfig/meshloop.example.tomlanddocs/install.md, verified against each CLI's own help/docs, not guessed. ADR 0003 forbids hardcoded flags in code; documented examples in config must still be checked.
Acceptance criteria
- A fixture-harness contract test for each delivery mode (stdin, embedded file placeholder).
meshloop doctorreports a harness with a verified template as dispatchable.- The example config documents which templates were verified, and against which CLI versions.
Notes
Public config contract change: consider whether it needs an ADR 0003 amendment.
🤖 Generated with Claude Code
Activity
smota commentedon Oct 7, 2026
A data point for the "verified invoke templates" part of this issue, from the
issues-46-47-56run (PR #63):The Claude worker was started through a PowerShell shim:
The worker still couldn't run
cargo. The log of attempt 5 says: "cargo fmt --allwas denied in both the Bash and PowerShell tools ("requires approval")". On Windows, Claude Code runs commands through its PowerShell tool, whichBash(...)rules don't cover. The:*prefix form may not match either.The result: three worker attempts in a row produced correct logic but never ran fmt, clippy or tests, and each failed verification on formatting or lint. Because worker output isn't saved (#48), it looked as if the workers were ignoring their instructions.
A verified Claude template should therefore:
Bash(cargo *)andPowerShell(cargo *), checked against the installed Claude Code versiondoctorthat asks the harness to run a harmless allowed command (e.g.cargo --version) and fails if it's denied🤖 Generated with Claude Code