Scan & Poll Orchestration¶

The scan and poll modules form the runtime pipeline of tradingview-strategy. scan.js performs a single full read of all indicators, while poll.js runs scans on a repeating interval with change detection.

scan.js -- Full Pipeline¶

scan() is the top-level pipeline orchestrator. It performs four sequential steps in a single invocation:

Step 1: Parallel MCP Reads¶

Six data sources are read simultaneously via Promise.all:

Reader	Source
`readChartState()`	Chart metadata (symbol, timeframe)
`readPrice()`	Current price data
`readBias()`	HTF Bias AI Pine graphics (tables, lines, labels)
`readSession()`	Session Bias Pine graphics (lines, labels, boxes)
`readOrderblocks()`	OB AI Pine graphics (lines, boxes, labels, tables)
`readSMT()`	SMT AI Pine graphics (lines, labels)

Each reader calls MCP tools (tv_get_pine_lines, tv_get_pine_labels, etc.) with the appropriate study_filter from contracts/indicator-names.js.

Step 2: Interpret Each Reader's Output¶

The raw MCP data passes through five interpreters that convert visual elements into typed signals:

Interpreter	Input	Output
`interpretBias(rawBias)`	Labels, lines, tables	Bias direction, DOL target, PDH/PDL/PWH/PWL levels
`interpretSession(rawSession)`	Labels, lines, boxes	Hunt side, sweep status, re-extension state, session mode
`interpretOrderblocks(rawOB)`	Lines, boxes, labels, tables	Bullish/bearish OB arrays, ATR/risk data
`interpretSMT(rawSMT)`	Lines, labels	SMT signals with direction, paired instrument
`interpretPrice(rawPrice)`	Price data	Current price, bid/ask if available

Step 3: Session Context¶

The current ET time is computed and used to determine:

current_window -- via getCurrentWindow(hour, minute, mode) from session-times.js
in_macro -- via checkMacro(hour, minute) from macro-windows.js
entry_window_active -- whether current time falls within the ENTRY_WINDOW for the detected session mode

Step 4: Build Flags¶

All interpreted signals and session context are passed to buildFlags(), which assembles the final StrategyFlags JSON object. This includes running the confluence scorer, no-trade filter, and setup detector.

Standalone Execution¶

node src/scan.js

When run directly, scan() executes once and prints the resulting StrategyFlags as formatted JSON to stdout. Exits with code 1 on failure.

poll.js -- Interval-Based Scanning¶

poll() wraps scan() in a repeating loop with configurable interval and delta detection.

Options¶

Parameter	Type	Default	Description
`interval`	`number`	`10000`	Polling interval in milliseconds
`onFlags`	`function`	--	Called with every scan result
`onDelta`	`function`	--	Called only when flags change from previous scan
`onError`	`function`	--	Called when a scan throws an error
`signal`	`AbortSignal`	--	AbortSignal to stop the polling loop

Delta Detection¶

The computeDelta() function compares two consecutive StrategyFlags snapshots and tracks changes across 9 key fields:

Tracked field	Change description
`bias.daily`	Daily bias direction changed
`bias.hit_target`	DOL target was hit (only triggers on `false` -> `true`)
`session.hunt.side`	Hunt side changed (e.g., `null` -> `HUNT_LOW`)
`session.current_window`	Session window transition (e.g., `gap_scan` -> `ny_am`)
`decision.setup_valid`	Setup validity toggled
`decision.confluence_score`	Confluence score changed
`structure.order_blocks.bullish.length`	Bullish OB count changed
`structure.order_blocks.bearish.length`	Bearish OB count changed
`smt.last_signal`	SMT signal changed

When any tracked field changes, onDelta receives an object with { changed: true, changes: [...] } where changes is an array of human-readable strings like "bias_daily: bullish -> bearish".

AbortSignal Support¶

The poll loop checks signal.aborted before each iteration and listens for the abort event during the inter-scan wait. This allows clean shutdown:

const ac = new AbortController();
process.on('SIGINT', () => ac.abort());

await poll({ signal: ac.signal, interval: 10000 });

JSONL Output (Standalone)¶

When run directly via node src/poll.js, each scan prints a single status line:

[2026-04-14T14:30:05.123Z] SI1! 5 | VALID long (score: 7)
  CHANGES: hunt: null -> HUNT_LOW, window: gap_scan -> ny_am

The default interval is 10 seconds. Press Ctrl+C to stop (SIGINT triggers the AbortController).

Dashboard Integration¶

The dashboard (dashboard/server.js) does not use poll() directly. Instead, it calls scan() on demand:

The readCurrentChart endpoint in the dashboard server imports and calls scan() when the user requests a refresh.
The dashboard SSE (server-sent events) stream can trigger scans on a timer and push results to the browser.
All scan results are the same StrategyFlags JSON shape, whether from scan.js, poll.js, or the dashboard.