[continuous-research-bot]

Why

Issue #17: the sensor's declared source, api.exchange.coinbase.com, was
added to .research/source-firewall.json (simulated feed retirement),
so every sense run drifts with source-firewalled instead of producing an
edition.

Evidence trail

Chosen source: https://www.bitstamp.net/api/v2/ohlc/btcusd/?step=86400&limit=20

• Host www.bitstamp.net is not present in .research/source-firewall.json
  (only api.exchange.coinbase.com is blocked).

• No API key required — plain unauthenticated GET.

• Plainly fetchable JSON (verified via curl, no JS rendering needed).

• Confirmed live via curl on 2026-07-04 (UTC "today" = 2026-07-04):

  {"data": {"pair": "BTC/USD", "ohlc": [
    {"timestamp": "1781913600", "open": "63487.34", "high": "64334.69", "low": "63133.21", "close": "64245.72", "volume": "610.71977158"},
    {"timestamp": "1782000000", "open": "64225.99", "high": "64522.00", "low": "63197.23", "close": "63237.18", "volume": "551.09674747"},
    ...
    {"timestamp": "1783123200", "open": "62522.45", "high": "62888...", "close": "62541.58", "volume": "..."}
  ]}}

  Decoding timestamp shows the buckets are UTC-midnight-aligned, one per
  calendar day, ascending, with the last bucket (1783123200 →
  2026-07-04T00:00:00Z) being today's still-in-progress candle:

  1782864000 2026-07-01T00:00:00.000Z close=59963.46
  1782950400 2026-07-02T00:00:00.000Z close=61479.10
  1783036800 2026-07-03T00:00:00.000Z close=62522.46
  1783123200 2026-07-04T00:00:00.000Z close=62541.58   <- today, incomplete, filtered out
  

• Entry contract: step=86400&limit=20 returns 20 daily buckets; after
  filtering out the current (incomplete) UTC day, 19 completed days remain
  — well over the required minimum of 9. Each bucket maps directly to
  { day: "YYYY-MM-DD", close: Number }, ascending (buckets already arrive
  ascending; sorted defensively by timestamp to guarantee the contract).

Change

sensor.mjs only:

• SOURCE → Bitstamp's public OHLC endpoint.
• fetchEntries() → reads res.json().data.ohlc, sorts by timestamp,
  drops the current UTC day, and maps {timestamp, close} (strings) to
  { day, close: Number }.

sensor-lib.mjs, the firewall, workflows, tests, and the artifact schema
are untouched.

Verification

• node --test → 10/10 passing.
• node sensor.mjs → emits:

  {"changed":true,"descriptor":"btcusd-2026-07-03","source":"https://www.bitstamp.net/api/v2/ohlc/btcusd/?step=86400&limit=20","retrievedAt":"2026-07-04T12:53:53.971Z","hash":"sha256:...","artifacts":["data/btcusd/btcusd-2026-07-03.json"]}

  No drift report written; data/btcusd/btcusd-2026-07-03.json contains a
  plausible edition (close: 62522.46, ma7_trend: "rising", etc.).

Fixes #17