Rename to /ESsence and write down the house rules

The header spent a whole line on a "CME FUTURES" eyebrow that told you nothing
the chart didn't — it only ever shows /ES. Dropping it takes the header from
64px to 44px and hands the space to the chart. The title becomes /ESsence.

AGENTS.md records the rules worth keeping, chief among them that a bug should
prompt the question of whether a unit test could reasonably have caught it —
written when the answer is yes, skipped when it is a rendering or data-source
quirk, and named after the failure rather than the function.

It is AGENTS.md rather than CLAUDE.md deliberately: opencode's instruction
loader walks up looking for AGENTS.md only and never reads CLAUDE.md, and the
ask-opencode skill asks the calling agent to distil house rules by hand rather
than forwarding a file. CLAUDE.md is a symlink to it so both tools resolve to
one source of truth.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

AGENTS.md

@@ -0,0 +1,70 @@
+# Working on this repo
+
+## Tests earn their place by catching a real bug
+
+When a bug is found, ask whether a unit test could reasonably have caught it. If
+yes, write that test with the fix. If no — a rendering artefact, a browser
+quirk, a data-source oddity — say so and don't add one.
+
+The bar is "would this have failed before the fix, and would it fail again if
+someone reintroduced it". Tests that restate the implementation, assert
+constructor defaults, or exercise paths nothing depends on are noise; they make
+the suite slow to run and expensive to change, which is how a suite stops being
+trusted.
+
+What has actually paid off here: bar aggregation and bucket boundaries, the
+store's replace-vs-append rules, level and alert arithmetic, parsing real
+market-data payloads (fixtures are trimmed real responses, not invented), and
+the invariants that would otherwise be silent — a comment must never become a
+level, a tick must never overwrite a settled bar, volume must be counted once.
+
+Name the test after the failure, not the function: `test_a_tick_cannot_overwrite
+_a_settled_bar` beats `test_put`.
+
+## Verify UI in a real browser
+
+Chart bugs are invisible from the outside — the API, the socket and the
+frontend source can each be correct while the screen is wrong. Drive the
+Playwright container against the dev stack:
+
+```
+docker exec -i chart-playwright-1 node - <<'EOF'
+const { chromium } = require('/usr/lib/node_modules/playwright');
+// launch with args:['--lang=en-US'] — see below
+EOF
+```
+
+**Always launch Chromium with `args: ['--lang=en-US']`.** The container has no
+usable locale, so Chromium reports `en-US@posix`, `Intl` throws, and the chart
+renders as a blank canvas that looks exactly like a broken app.
+
+`window.__chart` is a deliberate debug handle. Querying it separates "the data
+is missing" from "the data is off-screen" — which is how a viewport bug that
+three passing API checks had missed was finally found.
+
+## Running tests
+
+```
+docker exec chart-api-1 sh -c "cd /app && python -m pytest -q"
+```
+
+pytest + pytest-asyncio, declared in `requirements-dev.txt`. Tests live in
+`tests/`, import from `app.*`, and use `tmp_path` for anything that persists.
+Async paths are driven with `asyncio.run(...)` directly rather than async test
+markers.
+
+## Things that will cost you an hour
+
+- **Never write scratch `.py` files into the repo root.** It is bind-mounted, so
+  `--reload` restarts the app, and startup takes ~82 seconds. Pipe throwaway
+  scripts over stdin instead: `docker exec -i chart-api-1 python - <<'EOF'`.
+  Screenshots into `artifacts/` are safe; only `.py` triggers the reloader.
+- **Dev and production keep separate drawing stores.** Dev writes
+  `data/manual_lines.json`; production has its own Coolify volume. A fix that
+  "didn't land" is often the other store.
+- **Rebuild the image after touching `requirements.txt`.** The bind mount makes
+  source edits look live while an added dependency is simply absent.
+- **A deploy resets alert cooldowns**, so production may re-alert on whatever
+  price is sitting on. There is no durable state yet.
+- Times are epoch seconds, UTC, everywhere. Only the display is localised —
+  never shift the stored values.

CLAUDE.md

@@ -0,0 +1 @@
+AGENTS.md

app/bars/store.py

@@ -16,12 +16,34 @@ class InMemoryBarStore:
             lambda: deque(maxlen=max_bars_per_tf)
         )
 
+    # How far back from the tail a late bar may still land. A closed minute bar
+    # arrives a beat after the ticks that opened the next minute, so it is
+    # rarely more than a bucket or two behind.
+    LATE_BAR_LOOKBACK = 8
+
     def put(self, bar: Bar) -> None:
+        """Store a bar, replacing the bucket it belongs to.
+
+        Matching only the tail was enough while one closed bar arrived per
+        minute. With tick-built bars a minute's authoritative bar shows up
+        *after* ticks have already opened the next one, so the exchange's own
+        figures were being dropped and the approximation left in place forever.
+        """
         bars = self._bars[bar.tf]
-        if bars and bars[-1].t == bar.t:
-            bars[-1] = bar
-        elif not bars or bar.t > bars[-1].t:
+        if not bars or bar.t > bars[-1].t:
             bars.append(bar)
+            return
+        for index in range(len(bars) - 1, max(-1, len(bars) - self.LATE_BAR_LOOKBACK - 1), -1):
+            if bars[index].t == bar.t:
+                # A provisional bar must never overwrite a settled one: ticks
+                # keep arriving for a minute the exchange has already closed.
+                if bars[index].closed and not bar.closed:
+                    return
+                bars[index] = bar
+                return
+            if bars[index].t < bar.t:
+                # Buckets are ordered, so nothing further back can match.
+                return
 
     def get(self, tf: Timeframe, limit: int | None = None) -> list[Bar]:
         bars = list(self._bars[tf])

app/market/schwab.py

@@ -56,6 +56,12 @@ def parse_level_one(message: dict) -> list[tuple[int, float | None, int]]:
     ticks: list[tuple[int, float | None, int]] = []
     for content in message.get("content") or []:
         price = content.get(FIELD_LAST_PRICE)
+        # Zero is not a price. The field arrives as 0 on some updates, and
+        # because 0 is not None it opened a bar at zero, which dragged the low
+        # of that minute — and every timeframe aggregating it — to the bottom of
+        # the chart. Treated as absent, so the last real price carries forward.
+        if price is not None and float(price) <= 0:
+            price = None
         size = content.get(FIELD_LAST_SIZE)
         traded_at = content.get(FIELD_TRADE_TIME)
         # A trade stamp alongside a moved cumulative volume is a trade even when

docs/IMPLEMENTATION_PLAN.md

@@ -1526,3 +1526,22 @@ turned out to render exactly on its bar — zero pixels off at 1h, 30m and 15m
 because the anchor had snapped to the *drawn* timeframe extreme (the 09:00 1h
 low, 7744.25) while being checked against 1m bars, where it matches neither
 extreme. Always compare an anchor against the timeframe it was drawn on.
+
+**A zero price wrecked every timeframe's scale.** A LEVEL_ONE_FUTURES update
+arrived with `LAST_PRICE: 0`. The parser rejected `None` but `0` is not `None`,
+so a minute opened at zero — `o=0.0 h=7777.25 l=0.0` — and `provisional_higher`
+carried that low into 5m, 15m, 30m, 1h and the daily bar, flattening the price
+scale everywhere. Non-positive prices are now treated as absent, so the last
+real price carries forward, and the tick still counts as a trade.
+
+**The exchange's own bars were being dropped.** `store.put` replaced a bar only
+when it matched the *tail*. That held while one closed bar arrived per minute,
+but ticks open the next minute before CHART_FUTURES delivers the previous one —
+so the authoritative bar no longer matched the tail and was discarded, leaving
+the tick approximation and its partial volume in place permanently. `put` now
+searches back a bounded number of buckets, and refuses to let a provisional bar
+overwrite a settled one.
+
+Both were introduced by the tick feature and both are covered by tests: a zero
+price parses as a trade with no price, a late closed bar replaces its bucket and
+keeps the exchange's volume, and a tick cannot overwrite a settled bar.

static/index.html

@@ -3,7 +3,7 @@
 <head>
   <meta charset="utf-8">
   <meta name="viewport" content="width=device-width, initial-scale=1">
-  <title>/ES Confluence</title>
+  <title>/ESsence</title>
   <link rel="stylesheet" href="/static/style.css">
   <!-- Font Awesome Free 7.3.1, from unpkg like the other two dependencies.
        Pinned deliberately: an unpinned icon set is a silent redesign on someone
@@ -15,7 +15,7 @@
 <body>
   <div id="app">
     <header>
-      <div><span class="eyebrow">CME FUTURES</span><h1>/ES <strong>CONFLUENCE</strong></h1></div>
+      <h1><strong>/ES</strong>sence</h1>
       <div class="status" :class="status.stream"><i></i>{{ status.stream }}<span v-if="status.delay_minutes"> ({{ status.delay_minutes }}min delay)</span> · {{ status.source || 'source' }}</div>
     </header>
     <main>

static/style.css

@@ -2,7 +2,7 @@
 * { box-sizing:border-box; }
 body { margin:0; background:var(--bg); color:var(--fg); font:14px/1.45 "IBM Plex Mono", "SFMono-Regular", Consolas, monospace; }
 #app { min-height:100vh; padding:18px; }
-header { height:64px; display:flex; align-items:center; justify-content:space-between; border-bottom:1px solid var(--line); margin-bottom:16px; }
+header { height:44px; display:flex; align-items:center; justify-content:space-between; border-bottom:1px solid var(--line); margin-bottom:16px; }
 h1 { margin:0; font-size:22px; letter-spacing:-1px; } h1 strong { color:var(--accent); font-weight:600; }
 .eyebrow { color:var(--muted); font-size:9px; letter-spacing:2px; }
 .status { text-transform:uppercase; color:var(--muted); font-size:11px; }.status i { display:inline-block; width:7px; height:7px; border-radius:50%; background:var(--red); margin-right:8px; }.status.connected i,.status.replay i { background:var(--green); box-shadow:0 0 9px var(--green); }
@@ -51,7 +51,7 @@ aside { padding:16px; }h2 { margin:0 0 12px; color:var(--muted); font-size:11px;
 .armed-toggle { display:flex; align-items:center; gap:4px; font-size:10px; color:var(--accent); cursor:pointer; }
 .armed-toggle.off { color:var(--muted); text-decoration:line-through; }.optional { color:var(--muted); }.disabled { opacity:.45; }.score-hidden { margin-top:11px; color:var(--muted); line-height:1.25; }
 .cluster { margin:8px 0; padding:10px; border:1px solid var(--line); border-left:3px solid var(--green); background:var(--chart-bg); }.cluster.resistance { border-left-color:var(--red); }.cluster-top { display:flex; justify-content:space-between; text-transform:uppercase; font-size:10px; }.cluster-top strong { color:var(--accent); font-size:16px; }.zone { margin:4px 0; font-size:15px; }.members,.distance { color:var(--muted); font-size:9px; }.distance { margin-top:5px; }.alert-entry { white-space:pre-line; margin:8px 0; padding:9px; background:color-mix(in srgb,var(--accent) 8%,transparent); font-size:10px; }.alert-entry time { display:block; color:var(--accent); margin-bottom:4px; }
-@media (max-width:850px) { #app { padding:10px; }.chart-shell { min-width:0; }main { grid-template-columns:1fr; }.drawing-tools { flex-wrap:wrap; }.drawing-tools .line-name { width:110px; }#chart { height:55vh; min-height:360px; }aside { min-height:180px; }header { height:54px; }.chart-head { align-items:flex-start; flex-direction:column; }.timeframes { justify-content:flex-start; }.timeframes button { padding:5px 8px; } }
+@media (max-width:850px) { #app { padding:10px; }.chart-shell { min-width:0; }main { grid-template-columns:1fr; }.drawing-tools { flex-wrap:wrap; }.drawing-tools .line-name { width:110px; }#chart { height:55vh; min-height:360px; }aside { min-height:180px; }header { height:40px; }.chart-head { align-items:flex-start; flex-direction:column; }.timeframes { justify-content:flex-start; }.timeframes button { padding:5px 8px; } }
 /* --- chart comments ---------------------------------------------------- */
 .chart-comments { position:absolute; inset:0; pointer-events:none; z-index:4; }
 .chart-comment { position:absolute; max-width:210px; padding:4px 7px; border:1px solid var(--muted);

tests/test_schwab_source.py

@@ -279,3 +279,17 @@ def test_a_trade_known_only_by_its_volume_still_counts():
         ]
     }
     assert parse_level_one(volume_only) == [(1786356932000, None, 0)]
+
+
+def test_a_zero_last_price_is_not_a_price():
+    # Seen live: LAST_PRICE arrived as 0, and because 0 is not None it opened a
+    # bar at zero whose low dragged every aggregating timeframe to the floor.
+    zero = {"content": [{"key": "/ES", "LAST_PRICE": 0, "LAST_SIZE": 2,
+                         "TRADE_TIME_MILLIS": 1786356933000}]}
+    # Still a trade — size and stamp are there — but with no usable price, so
+    # the caller carries the last real one forward.
+    assert parse_level_one(zero) == [(1786356933000, None, 2)]
+
+
+def test_a_zero_price_with_no_trade_markers_is_dropped_entirely():
+    assert parse_level_one({"content": [{"key": "/ES", "LAST_PRICE": 0}]}) == []

tests/test_store.py

@@ -15,3 +15,36 @@ def test_store_replaces_forming_bar_and_bounds_history():
 
     assert [value.t for value in store.get(Timeframe.M1)] == [120, 180]
     assert store.get(Timeframe.M1, 1)[0].t == 180
+
+
+def test_a_closed_bar_replaces_its_bucket_behind_the_tail():
+    # Ticks open the next minute before the exchange's own bar for the previous
+    # one arrives. Matching only the tail dropped it, leaving the tick-built
+    # approximation — with its partial volume — in place permanently.
+    from app.bars.models import Bar, Timeframe
+    from app.bars.store import InMemoryBarStore
+
+    store = InMemoryBarStore(100)
+    common = dict(tf=Timeframe.M1, symbol="/ES", source="schwab")
+    store.put(Bar(t=60, o=1, h=2, l=1, c=2, v=5, closed=False, **common))
+    store.put(Bar(t=120, o=2, h=3, l=2, c=3, v=1, closed=False, **common))
+    # The authoritative bar for the first minute, arriving late.
+    store.put(Bar(t=60, o=1, h=9, l=1, c=4, v=400, closed=True, **common))
+
+    held = store.get(Timeframe.M1)
+    assert [b.t for b in held] == [60, 120]
+    assert held[0].closed is True
+    assert held[0].v == 400, "the exchange's volume must win over the tick estimate"
+
+
+def test_a_tick_cannot_overwrite_a_settled_bar():
+    from app.bars.models import Bar, Timeframe
+    from app.bars.store import InMemoryBarStore
+
+    store = InMemoryBarStore(100)
+    common = dict(tf=Timeframe.M1, symbol="/ES", source="schwab")
+    store.put(Bar(t=60, o=1, h=9, l=1, c=4, v=400, closed=True, **common))
+    store.put(Bar(t=60, o=1, h=2, l=1, c=2, v=5, closed=False, **common))
+
+    held = store.get(Timeframe.M1)[0]
+    assert held.closed is True and held.v == 400