Add event codegen support

[ioxde]

NOTE: I don't like throwing out AI generated PRs, but I think in this instance it is the right move. I made the typescript and rust version at the same time. Close if this is not the direction you want to go in.

What this does

Generates Rust code from Codama event definitions:

• Per-event files (events/{name}.rs) — Borsh-derived structs, discriminator constants, and a conditional from_bytes() method
• Program-level aggregation (events/{program}_events.rs) — enum of all events, identify_*() to match raw data against discriminators, and try_parse_*() to deserialize into typed variants

Follows the same visitor pattern used for instructions and accounts. Events reuse typeManifestVisitor by wrapping
event data in a synthetic definedTypeNode.

Discriminator handling

Supports constant, field, and size discriminators (and combinations).

from_bytes() is only generated when the event has at least one constant discriminator inside a hiddenPrefixTypeNode with all fixed-size entries. If the prefix contains variable-length fields, from_bytes() is skipped and a warning is logged.

Program-level identify / try_parse are only generated for events with resolvable discriminators. try_parse deserializes via BorshDeserialize directly rather than delegating to per-event from_bytes() — this keeps the program-level API self-contained and avoids double-checking discriminators.

Key implementation details

• constantDiscriminatorName and getDiscriminatorConditions were extracted from discriminatorConstant.ts as shared utilities — instructions only needed constants, events also need match conditions for the program-level identify function
• Program nodes are visited before render maps are merged so programsWithEventEnum is populated before eventsMod.njk checks membership

Limitations

• Non-fixed-size hidden prefixes skip from_bytes() generation (can't calculate a static skip offset)
• Field discriminators without a defaultValue are excluded from program-level aggregation (no default = no way to generate a match condition)

Tests

eventsPage.test.ts — 17 test cases covering struct generation, all discriminator variants, hidden prefix offset
logic, program-level enum/identify/parse, and module structure. E2E fixtures for Raydium CPMM (LpChangeEvent,
SwapEvent).

[changeset-bot]

🦋 Changeset detected

Latest commit: 1f2038e

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@codama/renderers-rust	Minor

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[ioxde]

Same issue as the renderers-js PR.

This guard and the *events ?? [] pattern should probably be fixed upstream so they can be removed.

See codama-idl/codama#991