fix(feed): dedup rule-driven counterparty/series rows on the timeline

[canalesb93]

What & why

Fixes #1915 — on the home Feed, a single retroactive (or sync-time) assign_counterparty / assign_series rule showed up as two events: the canonical rule_applied row and a duplicate membership row attributed to the system actor "Breadbox":

Netflix Counterparty ran a rule on 16 transactions with rule Netflix Counterparty
Breadbox assigned to a counterparty 16 transactions to Netflix

Root cause

When a rule fires assign_counterparty / assign_series, two annotations are written inside the same transaction:

1. rule_applied — attributed to the rule (the canonical audit record), and
2. a structural side-effect row (counterparty_assigned / series_assigned) — attributed to SystemActor() ("Breadbox").

The rule-source dedup in EnrichAnnotations (isRuleSourceDuplicate) already collapses this pair for tag/category kinds by dropping the side-effect row when its payload carries source: "rule". The membership kinds were added after that dedup landed and were never wired in — the membership write path didn't stamp source: "rule", and the dedup switch didn't list those kinds. So the side-effect row escaped dedup and rendered as a second feed event with the wrong-looking "Breadbox" actor.

The fix (mirrors the existing tag/category pattern)

• The rule-write paths (AssignCounterpartyFromRuleTx / AssignSeriesFromRuleTx) now stamp source: "rule" into the membership payload via a threaded source argument. User- and agent-authored assignments pass "" and continue to surface as first-class events.
• isRuleSourceDuplicate now drops counterparty_assigned / counterparty_unlinked / series_assigned / series_unlinked rows carrying source: "rule".
• formatRuleSummary phrases the surviving rule_applied row for the counterparty / series action fields (instead of the generic "applied") so the per-transaction timeline stays readable.

This fixes both surfaces that share EnrichAnnotations — the home Feed and the per-transaction activity timeline.

Evidence

This is a deduplication-logic bug, so the proof is a deterministic before/after of the same end-to-end path the screenshot exercises (seed 3 Netflix charges → create an assign_counterparty rule → apply retroactively → read ListFeedEvents).

Before the fix (dedup switch reverted to its old tag/category-only form) — the exact two rows from the issue:

--- FAIL: TestApplyRuleRetroactively_AssignCounterparty_FeedSingleEvent
    bulk_action kind="rule_applied"          actor="Netflix Counterparty"
    bulk_action kind="counterparty_assigned" actor="Breadbox"
    bulk_action events = 2, want 1 (rule_applied only; membership side-effect deduped)
FAIL

After the fix — collapses to one event:

--- PASS: TestApplyRuleRetroactively_AssignCounterparty_FeedSingleEvent (0.62s)
PASS
ok  	breadbox/internal/service

New regression tests added:

• TestApplyRuleRetroactively_AssignCounterparty_FeedSingleEvent (integration) — the end-to-end feed assertion above.
• TestEnrichAnnotations_DropsRuleSourcedMembership (unit) — rule-source membership rows are deduped; surviving summary reads Rule "Netflix Counterparty" set the counterparty retroactively.
• TestEnrichAnnotations_KeepsUserAuthoredMembership (unit) — user/agent-authored membership rows still survive.

Validation run locally:

• go build ./..., go vet ./... — clean.
• go test ./... (unit) — green for touched packages (the unrelated internal/agent process-reaping test fails identically on a clean checkout — pre-existing/env-specific).
• go test -tags integration -p 1 ./internal/service/ ./internal/sync/ — green.

Notes

• Docs: docs/activity-timeline.md dedup contract updated to list the membership kinds and to note "stamp source: "rule" and add the kind to isRuleSourceDuplicate" when introducing a new rule-write path.
• Attribution doctrine is unchanged: a rule firing is still attributed to the rule (rule_applied). Collapsing the duplicate removes the stray system-actor "Breadbox" row, which is what made the attribution look off in the issue.

🤖 Generated with Claude Code

https://claude.ai/code/session_01CvAru8AVLa95DGfZg4M1wj

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