logging

name	logging
description	How to log in the y5 compositor. Use whenever you add, change, or migrate logging — any time you'd reach for a log/print statement, "add a log", debug output, `tracing::*!`, `println!`, or a fatal `panic!` with a message. y5 has its own tracing-free structured logging; this skill is the source of truth for using it.

y5 logging

y5 has its own structured logging system. Never use tracing, log, or println!/ eprintln! for diagnostics in compositor code. Use the macros from compositor_model_debug_instance_record. Full reference: that crate's module docs (compositor.model/model.debug/debug.instance/instance.record).

The rule

• Levels: error!, warn!, info!, trace! — same format! args as tracing.
• Fatal: abort!("msg {x}") — logs at Error and panics (synchronously flushed first).
• No tracing / log / tracing-subscriber deps in new/changed crates. If a crate you touch still imports them only for logging, migrate the call sites and drop the deps.

Wiring a crate to log (one-time per crate)

The add-crate template already inserts this. If a crate lacks it, add to its lib.rs (after any leading #![...] inner attributes):

#[macro_use]
extern crate compositor_model_debug_instance_record;

and ensure its Cargo.toml has (it resolves via the workspace links — run compositor.workspace/link.all.sh if you just added the dep to a workspace that didn't have it):

compositor_model_debug_instance_record = { workspace = true }

Then call the macros from any module in the crate — no per-module use needed. The crate name and function path are attached automatically as filter tags.

Migrating tracing

tracing::info!(...) → info!(...) (likewise error!/warn!/trace!). Confirm the two lib.rs lines above exist, then remove tracing + tracing-subscriber from the crate's Cargo.toml. Grep the crate for tracing:: to be sure none remain.

Levels: two independent controls

• Compile-time: cargo features error/warn/info/trace on the record crate (set by the top-level execute dep). A disabled level compiles to nothing. abort! is never stripped.
• Runtime: COMPOSITOR_LOG_LEVEL (e.g. info,warn,error,trace) selects what is emitted among compiled-in levels.

Viewing logs

Records stream over gRPC (/tmp/y5-compositor-logs.sock) to the compositor.developer/developer.tool Tauri viewer (filter by crate/function/level, timeline, presets, dumps). Run the compositor with COMPOSITOR_LOG_LEVEL set, then cd compositor.developer/developer.tool/developer.tool.window/logs && npm run tauri dev. They also print dmesg-style to the compositor's stderr.

Do NOT

• Do not add tracing/log to Cargo.toml.
• Do not println!/eprintln! for diagnostics (use info!/trace!).
• Do not panic!("msg") for a logged fatal — use abort!("msg").
• Do not hand-write a per-crate logger — instance!() is the only mechanism.