Web Debug Toolbar / Profiler

Serenade’s browser profiler is the analogue of Symfony’s Web Debug Toolbar + Profiler. It is not the console (debug:container, ratatui TUI).

Surface	Role
Console (serenade-console / CLI)	Operator commands offline
Profiler (serenade-profiler)	Per-request browser debug in dev

Enablement

Disabled by default (ProfilerConfig::disabled()). Apps enable explicitly:

use std::sync::Arc;
use serenade_profiler::{AsyncProfilerMiddleware, ProfilerConfig, ProfileStore};

let store = Arc::new(ProfileStore::new(50));
let config = ProfilerConfig::enabled(50);
kernel.push_middleware(AsyncProfilerMiddleware::new(Arc::clone(&store), config));

Never leave the toolbar on by default in production configs.

Request flow

1. Middleware allocates a token, stores it on the request as _profiler_token.
2. Controllers run; apps may call record_query, record_debug, and record_view.
3. On the way out, HTML responses gain a fixed toolbar linking to /_profiler/{token}.
4. try_handle_profiler serves the index and detail pages.

Panels

Panel	Source
Request / routing / timing	Middleware
Logs	ProfilerLogLayer + request scope (with_profile_scope / install_log_scope)
Database	App adapters → record_query(store, token, QueryEvent)
Debug	App → record_debug(store, token, label, value)
Views	App → record_view(store, token, name, duration)

Symfony map (DebugBundle / VarDumper)

Symfony	Serenade
DebugBundle (dev dumps)	record_debug + Debug panel (dev-only via ProfilerConfig)
dump() / VarDumper	Plain labeled strings on the Debug panel (no object-graph walker, no dump server)
Twig / template timing panel	record_view + Views panel (apps name their own views)
Web Profiler toolbar	inject_toolbar + /_profiler/{token}

Keep dumps out of production: leave the profiler disabled outside local/dev configs.

Performance tooling

Request-scoped panels above are for dev inspection. Optional app-level hotpath / micro-benchmark recipes live in PERF.md when that guide lands; they complement the profiler and do not replace it.

Observability bridge

Install ProfilerLogLayer on your tracing subscriber (alongside serenade-observability channels). While a profile scope is active, matching events appear on that request’s Logs panel.

Console vs profiler

Documented also in KERNEL.md and OBSERVABILITY.md: CLI debug commands inspect the container and config; the profiler inspects one HTTP request in the browser.

Debug notes (KISS)

Apps may call record_debug to attach label/value strings to the current profile (Symfony DebugBundle / VarDumper habit: dump facts for this request, not a PHP object graph walker). See the Debug panel on /_profiler/{token} when the profiler is enabled.

Performance tooling

Function-level timing and allocation reports are not the toolbar. See PERF.md for optional hotpath app features.