Merging this PR will not alter performance

✅ 8 untouched benchmarks

_{Comparing provide-event-for-redis-state-expiry (32a343d) with main (d45a1bb)}

Greptile Summary

This PR propagates the triggering Event object through the Redis state-manager lock stack so that lock expiry errors and debug messages can surface which event was executing when the lock expired.

Key changes:

• StateModificationContext now allows event: Event | None (was Event) so proxies with no current event can pass None explicitly
• _lock in StateManagerRedis embeds the event name in the Redis lock ID (format {event_name}_{uuid_hex}), making it easier to identify the owning event when inspecting Redis
• LockExpiredError messages now include both the current lock ID (stored in Redis) and the expected lock ID, giving much richer diagnostics
• StateProxy stores and forwards the Event reference through all modify_state calls, including child proxies created via get_state
• The upload event handler and _process_background now pass the event into modify_state_with_links / StateProxy

Confidence Score: 4/5

• Safe to merge with minor stylistic fixes — no logic regressions; changes are additive and only affect observability/debugging of Redis lock expiry.
• The core logic of lock acquisition and release is unchanged; the PR only threads event context through existing call chains. The two items lowering the score are: (1) the _ separator in the lock ID format risks ambiguity when parsing lock IDs that contain event names with underscores, and (2) the new **context parameter in the public modify_state method is undocumented.
• reflex/istate/manager/redis.py — review the lock ID separator choice; reflex/app.py — missing docstring for **context

Important Files Changed

Sequence Diagram

sequenceDiagram
    participant Client
    participant App
    participant StateProxy
    participant StateManagerRedis
    participant Redis

    Client->>App: Event (e.g. on_click)
    App->>App: _process_background(state, event)
    App->>StateProxy: StateProxy(substate, event)
    Note over StateProxy: stores _self_event = event

    StateProxy->>App: modify_state(token, background=True, event=self._self_event)
    App->>StateManagerRedis: modify_state_with_links(token, event=event)
    StateManagerRedis->>StateManagerRedis: _try_modify_state(token, event=event)
    Note over StateManagerRedis: event_name = event.name
    StateManagerRedis->>StateManagerRedis: _lock(token, event_name=event_name)
    Note over StateManagerRedis: lock_id = f"{event_name}_{uuid_hex}".encode()
    StateManagerRedis->>Redis: SET lock_key lock_id PX lock_expiration
    Redis-->>StateManagerRedis: OK

    StateManagerRedis-->>App: yields state
    App-->>StateProxy: yields mutable_state

    StateProxy->>StateManagerRedis: set_state(token, state, lock_id=lock_id, event=event)
    StateManagerRedis->>Redis: GET lock_key
    Redis-->>StateManagerRedis: existing_lock_id
    alt lock_id matches
        StateManagerRedis->>Redis: SET substate_key pickle_state
    else lock expired
        StateManagerRedis->>StateManagerRedis: LockExpiredError\n"Current lock id: {existing_lock_id!r},\nexpected: {lock_id!r}.\nHappened in event: {event.name}"
    end

_{Last reviewed commit: "provide event for re..."}