buzz-acp: most log targets are invisible under the RUST_LOG the desktop injects

[rsaulo]

Summary

buzz-acp logs 102 call sites under bare targets (pool::prompt, acp::wire, canvas::fetch, …). EnvFilter matches targets by ::-separated prefix, so none of them match a buzz_acp filter — and buzz_acp is the only filter a managed agent ever runs with.

The result is that a managed agent's log records which channels it subscribed to, but not what it then did with them.

Why every managed agent hits this

Two independent places pin the filter to buzz_acp:

• the harness default: EnvFilter::try_from_default_env().unwrap_or_else(|_| EnvFilter::new("buzz_acp=info")) in lib.rs
• Buzz Desktop injects RUST_LOG=buzz_acp=info into every managed agent, which takes precedence over that default

Verified on a running agent:

$ ps eww -o command= -p <managed buzz-acp pid> | tr ' ' '\n' | grep RUST_LOG
RUST_LOG=buzz_acp=info

So changing only the harness default does not fix it — the environment wins. I tried that first.

Scope

19 distinct targets, 102 call sites, all invisible in a managed agent:

target	call sites
pool::prompt	17
canvas::fetch	11
acp::wire	11
pool::model	5
pool::effort	5
pool::permission	4
pool::metrics	4
engram::core	4
acp::usage	4
acp::update	4
acp::permission	3
acp::tool, acp::cancel, observer	2 each
acp::thought, acp::stream, acp::session, acp::plan, acp::init	1 each

By file: pool.rs 48, acp.rs 31, lib.rs 1, engram_fetch.rs 1.

What this costs in practice

These are the lines an operator needs when something goes wrong, and none of them are emitted:

• pool::model / pool::effort — why a model switch or an effort level did not apply
• canvas::fetch — why a channel canvas is missing from the prompt
• engram::core — why core memory was not injected
• acp::wire — the adapter conversation itself
• pool::prompt — what was actually dispatched

Nothing is broken at runtime; the information simply never reaches the log. It reads as "the agent did nothing", which is indistinguishable from an actual stall.

Repro

1. Run any managed agent from Buzz Desktop
2. Mention it so it takes a turn
3. grep 'pool::' ~/Library/Application\ Support/xyz.block.buzz.app/agents/logs/*.log

Zero matches, though the turn ran.

Suggested fix

Prefix the targets with the crate path — buzz_acp::pool::prompt, buzz_acp::acp::wire, and so on. That keeps the finer granularity for anyone who sets RUST_LOG deliberately (RUST_LOG=buzz_acp::acp::wire=debug still works), while making the lines visible under the filter the desktop already imposes, with no configuration change on either side.

Widening the desktop's injected RUST_LOG would also work, but it silently depends on the desktop and the harness agreeing on a list of target names.

Happy to send a PR if the prefix approach looks right to you.

Environment

macOS 15, Buzz Desktop built from main, buzz-acp from the same tree.