Chris Amow
7ce6d33bb5
The snap dot said where an anchor would land but not what it was, which made "the dot is in the wrong place" and "the dot is on the wrong bar" impossible to tell apart from a screenshot. It now carries a label with the price, whether it is a high or a low, and the bar's time. AGENTS.md gains the environment fact this session kept rediscovering: the agent runs on a remote machine over SSH while the user's browser runs on another, so headless runs here render on different hardware at a different size and pixel ratio, and "it passes in my headless run" is not evidence the user's problem is fixed. Three consecutive reproductions passed server-side while the chart was unusable on the user's screen. When a visual bug will not reproduce, match their viewport and deviceScaleFactor explicitly — and prefer putting the numbers on screen over asking for another console paste. Device pixel ratio is ruled out for the current trendline complaint: the bottom-sweep check lands 115 of 115 at 1600x1000 and at 1900x1400 with ratios of 1, 1.25, 1.5 and 2. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
89 lines
4.2 KiB
Markdown
89 lines
4.2 KiB
Markdown
# Working on this repo
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## Tests earn their place by catching a real bug
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When a bug is found, ask whether a unit test could reasonably have caught it. If
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yes, write that test with the fix. If no — a rendering artefact, a browser
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quirk, a data-source oddity — say so and don't add one.
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The bar is "would this have failed before the fix, and would it fail again if
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someone reintroduced it". Tests that restate the implementation, assert
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constructor defaults, or exercise paths nothing depends on are noise; they make
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the suite slow to run and expensive to change, which is how a suite stops being
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trusted.
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What has actually paid off here: bar aggregation and bucket boundaries, the
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store's replace-vs-append rules, level and alert arithmetic, parsing real
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market-data payloads (fixtures are trimmed real responses, not invented), and
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the invariants that would otherwise be silent — a comment must never become a
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level, a tick must never overwrite a settled bar, volume must be counted once.
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Name the test after the failure, not the function: `test_a_tick_cannot_overwrite
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_a_settled_bar` beats `test_put`.
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## Where things run
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**The agent works on a remote machine over SSH. The user's browser runs on a
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different machine.** Consequences, all learned the hard way:
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- You cannot see the user's screen, console, or cursor. Screenshots and pasted
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console output are the only window into it. Browser extensions that drive
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"your" Chrome do not help — they attach to the machine the browser is on.
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- Headless Chromium here renders on server hardware: different screen, window
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size and device pixel ratio from the user's. "Works in my headless run" is not
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evidence that it works for them. When a UI bug will not reproduce, match their
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viewport and `deviceScaleFactor` explicitly before concluding anything.
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- The dev stack is served to them over the network (e.g. `hera.local:8010`),
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which is the same app the headless browser reaches as `http://api:8000`.
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When a visual bug resists reproduction, prefer putting the numbers **on screen**
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in the app over asking for another console paste — one screenshot then carries
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the whole diagnosis.
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## Verify UI in a real browser
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Chart bugs are invisible from the outside — the API, the socket and the
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frontend source can each be correct while the screen is wrong. Drive the
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Playwright container against the dev stack:
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```
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docker exec -i chart-playwright-1 node - <<'EOF'
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const { chromium } = require('/usr/lib/node_modules/playwright');
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// launch with args:['--lang=en-US'] — see below
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EOF
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```
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**Always launch Chromium with `args: ['--lang=en-US']`.** The container has no
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usable locale, so Chromium reports `en-US@posix`, `Intl` throws, and the chart
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renders as a blank canvas that looks exactly like a broken app.
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`window.__chart` is a deliberate debug handle. Querying it separates "the data
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is missing" from "the data is off-screen" — which is how a viewport bug that
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three passing API checks had missed was finally found.
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## Running tests
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```
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docker exec chart-api-1 sh -c "cd /app && python -m pytest -q"
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```
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pytest + pytest-asyncio, declared in `requirements-dev.txt`. Tests live in
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`tests/`, import from `app.*`, and use `tmp_path` for anything that persists.
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Async paths are driven with `asyncio.run(...)` directly rather than async test
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markers.
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## Things that will cost you an hour
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- **Never write scratch `.py` files into the repo root.** It is bind-mounted, so
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`--reload` restarts the app, and startup takes ~82 seconds. Pipe throwaway
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scripts over stdin instead: `docker exec -i chart-api-1 python - <<'EOF'`.
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Screenshots into `artifacts/` are safe; only `.py` triggers the reloader.
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- **Dev and production keep separate drawing stores.** Dev writes
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`data/manual_lines.json`; production has its own Coolify volume. A fix that
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"didn't land" is often the other store.
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- **Rebuild the image after touching `requirements.txt`.** The bind mount makes
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source edits look live while an added dependency is simply absent.
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- **A deploy resets alert cooldowns**, so production may re-alert on whatever
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price is sitting on. There is no durable state yet.
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- Times are epoch seconds, UTC, everywhere. Only the display is localised —
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never shift the stored values.
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