events test

[Nanafancy]

Here's a summary of what was implemented for Issue #560:

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Changes Made

1. storage.rs — New EventDedup storage key

Added EventDedup(BytesN<32>) variant to the DataKey enum to track emitted event deduplication keys in persistent storage.

2. events.rs — Runtime pre-publish validation & event deduplication

New types and functions:

• EventDedupKey — contracttype for dedup storage keys
• compute_event_dedup_key(env, etid, ledger_seq, schema_ver, ts) → SHA-256 of the four core replay fields
• check_event_dedup(env, key) → Ok(true) if fresh, Ok(false) if duplicate
• record_event_emission(env, key) → records with 6-month TTL
• check_and_record_event_dedup(env, etid, ledger_seq, schema_ver, ts) → atomic check-and-record
• validate_emission_preconditions(env, etid, schema_ver, ledger_seq, ts) → full pre-publish gate that validates:
  • Non-zero event type ID
  • Schema version matches current version (prevents schema drift)
  • Event type ID matches a registered schema
  • Schema entry passes all canonical validation rules
  • Event is not a duplicate

3. events_test.rs — 11 new tests (18 total)

Test | What it validates -- | -- test_pre_publish_rejects_zero_event_type_id | Zero ETID rejected test_pre_publish_rejects_schema_version_mismatch | Wrong version rejected test_pre_publish_rejects_unknown_event_type_id | Unknown ETID rejected test_pre_publish_accepts_valid_event | Valid event passes all checks test_event_dedup_allows_first_emission | First emission is fresh test_event_dedup_rejects_duplicate_emission | Same params → duplicate test_event_dedup_different_ledger_is_fresh | Different ledger_seq → fresh test_event_dedup_different_event_type_is_fresh | Different ETID → fresh test_event_dedup_different_timestamp_is_fresh | Different timestamp → fresh test_pre_publish_rejects_duplicate_at_precondition_level | Full end-to-end duplicate rejection test_schema_invalid_namespace_detected_in_validation | Invalid namespace rejected test_replay_fields_present_in_every_schema | Every schema has all EVENT_REPLAY_FIELDS

4. README.md — Documented new features

Added a dedicated "Event Deduplication & Pre-Publish Validation" section documenting the API, behavior, and storage semantics.

▸Worked · 1 step

closes #560

[MaryammAli]

LGTM