03 · Editor · horizon-01-compact

Compact the session

core

Brief

An agent has been working for two hours on a data pipeline migration. Its window is nearly full. Below is the session log, roughly 1,600 tokens of it, and it is about to be discarded and replaced by whatever you write.

Everything the agent will know after the reset is what you carry across. There is no way to recover the rest.

Task

Write the compaction summary in 320 tokens or fewer. Preserve the state the agent needs to continue. Drop what has been resolved.

Graded on

Live state preservedRequired×4.0

Resolved noise dropped×2.0

Actually compressed×2.0

Delineated×1.5

Within budget×1.0

Required — a miss caps the score, whatever the rest do.

Hints

compaction

counting…

[session log — 1,600 tokens]

USER: We need to migrate the ingest pipeline off the legacy loader.

AGENT: Reading repository structure... [tool: list_files → 340 lines]
I can see ingest/legacy_loader.py, ingest/parser.py, and ingest/schema.py.

AGENT: [tool: read_file ingest/legacy_loader.py → 210 lines]
The legacy loader uses a synchronous batch pattern with a hardcoded
2,000-row page size.

AGENT: I'll write the replacement as an async streaming loader.
[tool: write_file ingest/stream_loader.py → created, 180 lines]

AGENT: [tool: run_tests → 14 passed, 3 failed]
Three failures, all in test_parser.py, all timeouts.

AGENT: [tool: read_file tests/test_parser.py → 95 lines]
The tests assume synchronous iteration. I'll update them to async.
[tool: write_file tests/test_parser.py → updated]
[tool: run_tests → 17 passed]

USER: Careful — test_parser also runs in the nightly job against real
volumes. Don't change its timeout semantics.

AGENT: Understood. I reverted the timeout change and kept only the async
iteration change. [tool: write_file tests/test_parser.py → updated]
[tool: run_tests → 17 passed]

AGENT: [tool: read_file ingest/schema.py → 120 lines]
Note: schema.py has a column ordering assumption that the legacy loader
satisfied implicitly by its batch ordering. The streaming loader does not
guarantee that ordering. This is unresolved — I have not fixed it and it
is not covered by any test.

USER: Let's decide on that later. What about the config?

AGENT: [tool: read_file config/pipeline.yaml → 60 lines]
The page size is set in two places: config/pipeline.yaml and a default in
legacy_loader.py. I've moved it to config only.
[tool: write_file config/pipeline.yaml → updated, page_size: 2000]

AGENT: [tool: run_tests → 17 passed]

USER: Good. Also we agreed last week we're keeping the legacy loader in
place behind a feature flag for one release cycle, not deleting it.

AGENT: Noted. I'll add the flag rather than removing legacy_loader.py.
[tool: read_file config/flags.py → 40 lines]
[tool: write_file config/flags.py → added USE_STREAM_LOADER, default False]
[tool: run_tests → 17 passed]

AGENT: [tool: run_linter → 6 warnings, all line-length in stream_loader.py]
[tool: write_file ingest/stream_loader.py → reformatted]
[tool: run_linter → clean]

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