Greptile Summary

This PR fixes a correctness bug in the delete-on-empty (DOE) background task and tightens the semantics of DOE deadline arming. The bug was that PendingStreamDoe collapsed multiple pending (deadline, min_age) entries for a stream into a single pair of maxima, which could prevent a stream from being deleted when a lower-deadline/lower-min_age entry was actually eligible while the aggregated maximum values were not. The fix replaces the aggregated struct with Vec<PendingDoeEntry> and evaluates each entry's original pair independently using any().

Key changes:

• Bug fix (stream_doe.rs): stream_doe_is_eligible now checks each stored (deadline, min_age) entry independently — any() — instead of using aggregated (max_deadline, max_min_age).
• Unified delay helper (streamer.rs): doe_arm_delay(retention_age, min_age) = retention_age + min_age + DOE_DEADLINE_REFRESH_PERIOD is now the single formula used across all arming paths (append, trim, create, reconfigure).
• Prospective-only arming (streams.rs): create_stream and reconfigure_stream only arm a new deadline for the initial None → Some DOE enable transition; changes to an already-enabled DOE config (different min_age, changed retention policy) no longer write a new deadline — the next organic arming (via append or trim) will pick up the updated configuration.
• Test coverage: Four new integration tests directly exercise the corrected eligibility logic, the enable-transition arming, and the prospective-only invariant.

Confidence Score: 5/5

• This PR is safe to merge — it is a targeted, well-tested bug fix with no new external dependencies or protocol changes.
• All three changed files have a single, coherent purpose. The eligibility fix is mathematically straightforward (max-aggregation replaced by per-entry any()), and the prospective-only arming guard is clearly expressed and directly tested by two new integration tests. The shared doe_arm_delay helper eliminates the previously divergent delay calculations without changing observable semantics for existing deployments. No unsafe code, no schema migrations, and existing tests continue to pass.
• No files require special attention.

Important Files Changed

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[DOE Arming Paths] --> B[create_stream new stream]
    A --> C[create_stream CreateOrReconfigure]
    A --> D[reconfigure_stream]
    A --> E[arm_doe_maybe after trim empties stream]
    A --> F[maybe_doe_deadline on append]

    B --> G[arm: doe_arm_delay\nretention_age plus min_age plus 600s]
    C -->|prior DOE was None| G
    C -->|prior DOE was Some| SKIP1[skip - prospective only]
    D -->|prior DOE was None, now Some| G
    D -->|prior DOE already Some| SKIP2[skip - prospective only]
    E --> G
    F -->|retention_age present plus refresh elapsed| G

    G --> H[(KV entry: deadline plus stream_id = min_age)]

    H --> I[tick_stream_doe: list expired entries]
    I --> J{stream_has_records?}
    J -->|yes| K[clear deadlines, skip delete]
    J -->|no| L{any entry satisfies:\nwrite_ts plus min_age le deadline?}
    L -->|yes| M[delete_stream]
    L -->|no| K
    M --> N[clear_doe_deadlines]
    K --> N

_{Last reviewed commit: 08714f5}

@greptileai rereview

@greptileai final review