Context
-------
The Provider protocol is satisfied. This commit adds the first cut of
the concrete Trading212 implementation: one page of fills, mapped to
canonical Activities. Pagination, retries, and checkpointing on
resume are deliberately deferred to the next commit so this one stays
focused on the raw shape translation.
Design decisions
----------------
- One provider instance serves every T212 wrapper (ISA + Invest). T212
exposes one API key per wrapper, so the caller hands over a list of
(Account, api_key) pairs. `accounts()` returns only the Accounts —
the keys never escape the provider.
- Auth: literal `Authorization: <api_key>`, NOT `Bearer <api_key>`.
T212 quietly returns 401 for Bearer-prefixed keys. The test locks
that in.
- Sell detection: T212 signs quantity (negative means closing a long
or opening a short). We flip on the sign and store `abs(quantity)`,
matching the Wealthfolio BUY/SELL convention.
- Null fills (cancelled orders) are silently dropped at parse time
rather than surfacing to the caller.
- `external_id = t212:fill:<fill.id>` — the fill ID is stable per
T212 docs and survives order cancellation/modification semantics.
- Ticker normalisation runs on ingress so downstream dedup + Wealthfolio
see `VUAG` even though T212 reports `VUAGl_EQ`.
- `since` / `before` filter on `filledAt`. `before` is half-open
(`< before`) so CronJobs can chain adjacent windows without
double-counting the boundary.
Explicitly NOT in this change:
- Pagination (nextPagePath walk)
- 429 / 5xx retry
- Dividend / deposit endpoints (deferred — Phase 1.1, filed as
beads follow-up if needed)
This change
-----------
- broker_sync/providers/trading212.py: `Trading212Provider` class +
`Trading212Error` / `Trading212AuthError` exception hierarchy.
`_item_to_activity` is pure and returns Optional so cancelled
fills short-circuit without raising.
- tests/providers/test_trading212.py: MockTransport-driven tests for
auth header shape, fill→Activity mapping (buy + sell sign flip),
null-fill skip, since-filter, and both error types.
Test plan
---------
## Automated
- poetry run pytest -q → 61 passed in 0.60s
- poetry run mypy broker_sync tests → Success: no issues found in 27 source files
- poetry run ruff check . → All checks passed!
## Manual Verification
Deferred to the CLI wiring commit — the live endpoint is 6 calls/min
and the full-volume dry run belongs with the env-driven command, not
the unit-level commit.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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