feat: message ack with atomic cleanup (story 1.8)

[vieiralucas]

Summary

• Implement handle_ack in scheduler: validates lease exists, parses expiry from lease value, finds message key by scanning messages CF, atomically deletes message + lease + lease_expiry via WriteBatch
• Implement Ack gRPC RPC with UUID parsing and input validation
• Add parse_expiry_from_lease_value() to keys module
• Acking unknown or already-acked message returns NOT_FOUND (idempotent)

Test plan

• Full lifecycle: enqueue -> lease -> ack -> verify message and lease deleted from storage
• Ack unknown message returns MessageNotFound
• Double ack returns MessageNotFound on second call (idempotent)
• Ack without lease returns error
• 48 tests pass, clippy clean, cargo fmt clean

Recreated after GitHub auto-closed the original PR #8

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Summary by cubic

Adds message acknowledgment (Story 1.8). Ack atomically removes the message, lease, and lease expiry, is idempotent, and rejects corrupt lease values.

• New Features

  • Scheduler: handle_ack validates lease, parses expiry, finds the message key, and deletes in one WriteBatch.
  • Server: Ack RPC with input checks, UUID parsing, and error mapping (MessageNotFound -> NOT_FOUND, CorruptData/Storage -> INTERNAL).

• Bug Fixes

  • Validate lease value structure and propagate storage errors when scanning messages to prevent “ghost” acks.
  • Per-queue round-robin delivery and error logging on lease rollback.

^{Written for commit 2bd310c. Summary will update on new commits.}

[cubic-dev-ai]

2 issues found across 7 files

Prompt for AI agents (all issues)

Check if these issues are valid — if so, understand the root cause of each and fix them.


<file name="crates/fila-core/src/storage/keys.rs">

<violation number="1" location="crates/fila-core/src/storage/keys.rs:103">
P2: `parse_expiry_from_lease_value` accepts any buffer ≥ 8 bytes and ignores the length prefix/separator. This can treat corrupted lease values as valid and derive a wrong expiry, leaving the real `lease_expiry` entry orphaned. Consider validating the encoded length and separator before parsing the expiry.</violation>
</file>

<file name="crates/fila-core/src/broker/scheduler.rs">

<violation number="1" location="crates/fila-core/src/broker/scheduler.rs:253">
P2: `find_message_key` drops `list_messages` errors, so `handle_ack` will still delete the lease/expiry and return success even when message scanning failed, leaving the message in the queue to be redelivered. Propagate the storage error instead of treating it as “message not found.”</violation>
</file>

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