mirror of
https://github.com/bitsocialnet/5chan.git
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Tommaso CasaburiandGitHub
da03239bb2
* chore(profiling): collect serializable react-scan reports * perf(routing): rerender only when directory winner changes * perf(zustand): remove shallow warning hot path * perf(state): narrow directory lifecycle updates * perf(home): avoid redundant stats render work * perf(posts): isolate live loading subscriptions * perf(chrome): skip unchanged shell rerenders * fix(profiling): drop unsupported render metric * perf(feeds): skip unchanged loading state renders * perf(home): stop resolved stats collector renders * chore(agent run): record rerender verification * perf(home): defer stats requests until metadata resolves * perf(startup): load protocol modules on demand * chore(agent run): record acquisition and startup profiles
168 lines
8.2 KiB
Markdown
168 lines
8.2 KiB
Markdown
---
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name: profile-browsing
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description: Profile app performance while browsing, collecting Web Vitals and React rerender data via react-scan. Orchestrates parallel profiler subagents via playwright-cli to capture navigation timing, long tasks, layout shifts, LCP, React commit counts, render bursts, and per-component render data. Use when profiling browsing performance, finding bottlenecks, diagnosing excessive rerenders, or auditing page performance.
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---
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# Profile Browsing Performance
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Two-layer profiling: browser-level symptoms (Web Vitals, long tasks, scroll jank) and React-level diagnosis (commit counts, render bursts, per-component render data from react-scan). Each profiler subagent runs in its own browser session and context window.
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## Prerequisites
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- Dev server running at https://5chan.localhost (`yarn start` via Portless)
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- `playwright-cli` installed (`npm install -g @playwright/cli@latest`)
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**IMPORTANT:** The orchestrator (you) is responsible for ensuring exactly ONE dev server is running. Profiler subagents must NEVER start a dev server themselves.
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### react-scan (already configured)
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`src/lib/react-scan.ts` runs react-scan in dev mode. It:
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- Highlights rerendering components visually (toolbar + overlay)
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- Accumulates per-component render counts and times via react-scan's `onRender` option
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- Exposes `window.__getReactScanReport()` and `window.__resetReactScanReport()` for programmatic collection
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`__getReactScanReport()` returns a plain object: `{ ComponentName: { count, time } }`.
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**Do not use react-scan's own `getReport()`.** It reads `Store.legacyReportData`, which react-scan 0.5.3 never writes to, so it always returns an empty `Map`. The live `Store.reportData` is no better: it is only populated while the toolbar is visible *and* a component is manually focused in the inspector, neither of which holds under automation. The app's `onRender` collector exists precisely because of this. Also note a `Map` cannot be serialized — `JSON.stringify(new Map())` is `"{}"` regardless of contents — which is why the collector returns a plain object.
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The profiler's `addInitScript` sets `window.__PROFILING__ = true` before the app loads, which tells react-scan to disable its toolbar and sounds during automated runs.
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No additional setup needed — react-scan is already a devDependency and imported in the entry file.
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## Step 0: Ensure Dev Server is Running
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Before spawning any profiler subagents, verify exactly one dev server is available:
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```bash
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# Check if the dev server is reachable
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curl -sf https://5chan.localhost -o /dev/null && echo "OK" || echo "NOT RUNNING"
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```
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- If **OK**: proceed to Step 1.
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- If **NOT RUNNING**: start one instance with `yarn start` (backgrounded), then poll until it responds. Do NOT start more than one.
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- If a dev server is already running on a different port (check `ps aux | grep vite`), reuse it — do not start another.
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## Step 1: Define Route Batches
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Split routes into batches of 2–4 for parallel profiling.
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**Default batches** (adjust boards as needed):
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| Batch | Session | Routes | Focus |
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|-------|---------|--------|-------|
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| 1 | `prof-1` | `/all`, `/all/catalog` | Multi-board feed + catalog |
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| 2 | `prof-2` | `/biz`, `/biz/catalog` | Single board feed + catalog |
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| 3 | `prof-3` | `/pol`, `/pol/catalog`, `/g`, `/g/catalog` | Board switching (feed reloads) |
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Keep batches balanced. Add thread views (`/:boardIdentifier/thread/:cid`) as needed.
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## Step 2: Spawn Profiler Subagents
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Read the profiler subagent definition at `.codex/agents/profiler.toml`. Then spawn one `profiler` subagent per batch **in parallel** using Codex's current delegation tool:
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```
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For each batch, create a subagent request:
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agent_type: "profiler"
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prompt: |
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Session name: "prof-N"
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Routes to profile: /route1, /route2, ...
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Any non-default app URL or extra profiling constraints
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```
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Spawn up to 4 subagents simultaneously. Each opens its own browser session, navigates routes, scrolls, collects both Web Vitals and react-scan data per route, and returns a structured issues list.
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**Trade-off:** Parallel is faster but may skew timing results under heavy machine load. For precise measurements, spawn sequentially.
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## Step 3: Merge Results
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Collect structured output from each subagent and merge:
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1. Concatenate all Critical / Warning / React Rerenders / Scroll Jank / Info items
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2. Combine per-view summary tables into one
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3. Merge react-scan component data across routes (same component appearing in multiple routes = sum counts)
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4. Deduplicate shared issues (e.g., same slow resource across routes)
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5. Sort by severity (Critical first)
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## Step 4: Final Report
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```markdown
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## Performance Profile Results
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### Critical
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- [metric]: [value] at [route] — [what likely needs fixing]
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### Warning
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- [metric]: [value] at [route] — [what likely needs fixing]
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### React Rerenders
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- [route]: [N] commits during load, [M] during scroll — [likely cause]
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- Render bursts detected at [routes] — suggests cascading state updates
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- Top rerendering components (react-scan):
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- [ComponentName]: [total count] renders across [routes], [time]ms total
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- [ComponentName]: [total count] renders across [routes], [time]ms total
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### Scroll Jank
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- [route]: [N] long tasks during scroll (max [X]ms), [M] React commits — [likely cause]
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### Info
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- [observations]
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### Per-View Summary
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| View | Nav (ms) | Long Tasks | CLS | LCP (ms) | Commits | Scroll Commits | Bursts | Top Component |
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|------|----------|-----------|-----|-----------|---------|----------------|--------|---------------|
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| /all | ... | ... | ... | ... | ... | ... | ... | ... |
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```
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## Interpreting React Metrics
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| Signal | Likely cause | Fix direction |
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|--------|-------------|---------------|
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| High commits, no long tasks | Frequent cheap rerenders | `React.memo`, stabilize props |
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| High commits + long tasks | Expensive rerenders | Profile render cost, split components |
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| High scroll commits | Scroll/intersection observer triggering renders | Throttle handlers, memoize list items |
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| Render bursts (>5 in 100ms) | Cascading state updates | Batch updates, review Zustand selectors |
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| react-scan: component with >30 renders | Missing memoization or unstable references | `useMemo`/`useCallback`, check parent renders |
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| react-scan: component with >50ms time | Expensive render function | Split component, move work out of render |
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## Element-source follow-up
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When `react-scan` identifies a rerender hotspot but you still need the exact file behind a concrete DOM node, hand off to `$inspect-elements`.
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```bash
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playwright-cli -s=prof-followup eval "async el => JSON.stringify(await window.__ELEMENT_SOURCE__.resolve(el))" e7
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```
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Use `source.filePath` as the direct edit target and `stack` to understand which parent components own the node.
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## Step 5: Cleanup
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After profiling is complete and the report is delivered, verify no orphaned processes were left behind:
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```bash
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# Check for any Vite dev servers started during profiling
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ps aux | grep 'vite.*--port' | grep -v grep
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```
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- If the dev server was already running before Step 0, leave it alone.
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- If the orchestrator started the dev server in Step 0, kill it now.
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- If there are multiple Vite processes (should never happen), kill the extras and warn the user.
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Also close any leftover playwright-cli sessions:
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```bash
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# Close any profiling sessions that weren't properly closed
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playwright-cli -s=prof-1 close 2>/dev/null
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playwright-cli -s=prof-2 close 2>/dev/null
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playwright-cli -s=prof-3 close 2>/dev/null
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```
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## Notes
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- **Session isolation**: Each subagent uses a named playwright-cli session (`-s=prof-N`).
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- **Context isolation**: Each subagent runs in its own context window.
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- **Per-route collection**: Data resets on each `goto` — the profiler collects before navigating away.
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- **addInitScript persistence**: Instrumentation re-injects automatically in each new document.
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- **Tracing**: Each subagent produces a `trace.zip` viewable in [Trace Viewer](https://trace.playwright.dev).
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- **Board codes**: `biz`, `pol`, `g`, `a`, `v`, etc. map to community addresses via the directory.
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- **Empty react-scan report**: react-scan is a dynamic import, so `__getReactScanReport()` returns `{}` for the first moment after a `goto`. If it is empty, wait ~1s and re-read before falling back to commit counts + render bursts (still useful, just no component names).
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