83 lines
3.3 KiB
Markdown
83 lines
3.3 KiB
Markdown
# T1.6 — Prompt and output blob capture
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| Field | Value |
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|---|---|
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| Phase | P1 — Walking skeleton |
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| Size | S — under 1 day |
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| Status | Not started |
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| Flags | — |
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| Spec | inlined below |
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| Blocks | — |
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## Goal
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Write the prompt to the blob store when it is built, and the output when the
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model responds. Record both as `BlobRef` on the attempt.
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## Facts (inlined — no spec read needed)
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- Two capture points: `prompt-built` and model response. **The prior
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implementation had neither** — every downstream consumer worked from
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identifiers alone and could not answer "what did the agent actually see".
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- Prompts and outputs are large, so they go **by reference**; context partitions
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are identifiers and go inline (T1.5). That split is what makes lazy blob access
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(T4.3) possible.
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- Blobs are content-addressed within a tenant, never across (T0.7).
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- A `BlobRef` whose body later returns `None` is normal after reduction (T8.4) —
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the log carries a `Reduced { original, summary }` event saying what replaced it.
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## Steps
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1. At prompt assembly, serialize the final prompt, `BlobStore::put`, keep the
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returned `BlobRef`.
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2. On model response, `put` the raw output, keep its `BlobRef`.
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3. Attach both refs to the attempt record; commit them in the same
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`EventLog::commit` as the attempt transition, so a crash cannot leave a
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dangling ref in state with no log record.
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4. Surface as `AttemptView.prompt: Option<BlobRef>` and
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`AttemptView.output: Option<BlobRef>`.
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5. Test across a process restart: complete a run, drop the process, reopen the
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store, fetch the prompt by ref, assert the text.
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## Acceptance
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- Prompt text retrievable from the blob store by ref **after a process restart**.
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## Verify
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**Harness:** embedded store on a temp path that survives process exit; the test
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runs the agent in a **child process**, then reopens the store in the parent.
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**Integration test** — `tests/it_blob_capture_restart.rs`:
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1. Child process: run one model step to completion, print the store path, exit.
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2. Parent: reopen the store, read the attempt, take `prompt` and `output` refs.
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3. `BlobStore::get` both; assert the prompt bytes equal the **assembled** prompt
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(with template variables substituted), not the template.
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4. Re-hash both bodies; assert each matches its ref.
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5. Crash case: arm a fault hook between the blob `put` and the commit; assert on
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reopen there is no attempt record pointing at a body-less ref, and no orphan
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body that no record points at.
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**Command:** `cargo test -p executor blob_capture -- --test-threads=1`
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**False pass:**
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- Reading the blob back in the same process from a warm cache. The restart is the
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point — an in-memory blob map passes everything else.
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- Asserting the prompt is non-empty rather than comparing to the expected
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assembled text. Capturing the template instead of the rendered prompt passes a
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non-empty check.
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## Traps
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- Putting the blob outside the commit transaction and recording the ref inside
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it, or the reverse. Either way a crash leaves a ref with no body or a body no
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record points at.
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- Capturing the prompt template instead of the assembled prompt. The template is
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in the workflow definition; what the model saw is not.
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---
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Background (not required to do this task):
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[rust-agentic-sys.md](../../../rust-agentic-sys.md) §8.6, §10.1 ·
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[rust-agentic-task.md](../../../rust-agentic-task.md)
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