memory2: time windowing on Stream

[leshy]

Adds time-based windowing to Stream - shared base both #2306 (stream alignment) and #2314 (go2dds) need

• from_time(s) / to_time(s) - relative to the first observation
• from_timestamp(ts) / to_timestamp(ts) - absolute epoch seconds

[greptile-apps]

Greptile Summary

Adds four time-windowing methods to Stream (from_time, to_time, from_timestamp, to_timestamp) that let callers slice a stream by relative duration (anchored to the first observation) or by absolute epoch timestamp. Both None-passthrough and empty-stream edge cases are handled.

• from_time(s) / to_time(s) eagerly resolve the current stream's first observation at build time, then delegate to the existing after() / before() filters for the computed cutoff.
• from_timestamp(ts) / to_timestamp(ts) are thin wrappers around after() / before() with no eager evaluation.
• Nine new tests cover relative, absolute, chained, None-bound, and empty-stream scenarios.

Confidence Score: 5/5

Safe to merge — the new methods are additive, delegate entirely to the established after()/before() filter primitives, and do not touch any existing code paths.

All four methods are thin, well-tested wrappers. The empty-stream guard (catching LookupError from first()) is handled correctly for static and pre-filtered streams. Test coverage is thorough, including chained relative+absolute combinations and boundary conditions.

No files require special attention.

Important Files Changed

Filename	Overview
dimos/memory2/stream.py	Adds four time-windowing methods with correct empty-stream guard and consistent delegation to existing after()/before() filters; no regressions to existing API.
dimos/memory2/test_stream.py	Comprehensive test class covers relative, absolute, chained, None-bound, and empty-stream cases; all assertions are arithmetically correct against the fixture data.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    FT["from_time(s)"] --> FT1{"s is None?"}
    FT1 -->|yes| FT2["return self"]
    FT1 -->|no| FT3["self.first()"]
    FT3 -->|LookupError| FT4["return self (empty)"]
    FT3 -->|"t0"| FT5["self.after(t0 + s)"]
    FT5 --> AF["AfterFilter appended to query"]

    TT["to_time(s)"] --> TT1{"s is None?"}
    TT1 -->|yes| TT2["return self"]
    TT1 -->|no| TT3["self.first()"]
    TT3 -->|LookupError| TT4["return self (empty)"]
    TT3 -->|"t0"| TT5["self.before(t0 + s)"]
    TT5 --> BF["BeforeFilter appended to query"]

    FTS["from_timestamp(ts)"] --> FTS1{"ts is None?"}
    FTS1 -->|yes| FTS2["return self"]
    FTS1 -->|no| FTS3["self.after(ts)"]
    FTS3 --> AF

    TTS["to_timestamp(ts)"] --> TTS1{"ts is None?"}
    TTS1 -->|yes| TTS2["return self"]
    TTS1 -->|no| TTS3["self.before(ts)"]
    TTS3 --> BF

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_{Reviews (3): Last reviewed commit: "memory2: from_time/to_time yield empty o..." | Re-trigger Greptile}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ All tests successful. No failed tests found.

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