mirror of
https://github.com/fabro-sh/fabro.git
synced 2026-09-20 00:11:34 +00:00
c987766641
## Summary
Replaces the whole-history `chars / 4` compaction trigger with a Claude
Code-style hot-path estimator: find the latest assistant turn with real
provider-reported `usage.total_tokens()`, use that as the baseline, and
add local char estimates only for turns appended after it. This makes
compaction sensitive to actual provider-reported context usage
(including cache read/write and reasoning tokens) without adding any
provider token-count API calls.
### Plan Summary
- **New estimator** (`estimate_active_context_usage`): returns a
`ContextEstimate` with both a token count and an `ContextEstimateMethod`
enum tag (`ApiUsagePlusLocalDelta` or `LocalEstimate`).
- **`check_context_usage`** now returns `Option<ContextEstimate>`
instead of `bool`, and includes `estimate_method` in warning `details`.
The caller passes the estimate directly into `compact_context`, avoiding
a double-compute.
- **`compact_context`** signature drops `system_prompt` (no longer
needed) and takes the pre-computed `ContextEstimate`. The
`CompactionStarted` event is now emitted *after* the `turns.len() <=
preserve_count` no-op guard, so a no-op can never emit `Started` without
`Completed`.
- **`History::compact`** invalidates preserved assistant `usage` (resets
to `TokenCounts::default()`) so a preserved turn's pre-compaction
provider baseline never becomes the next estimate's anchor. Content,
tool calls, provider parts, and response IDs are untouched.
- **`session.compact_if_needed`** restructured to early-return on `None`
from `check_context_usage` or on compaction disabled, simplifying the
nesting.
## Key design decisions
**Why invalidate preserved assistant usage?** After compaction the prior
turns are gone, so a stored `total_tokens` from before compaction would
overstate the new context. The authoritative billing record is in
emitted run events, not in mutable runtime history.
**Why return `Option<ContextEstimate>` from `check_context_usage`?**
Avoids recomputing the estimate in `compact_context`. It also makes the
call-site idiom (`let Some(estimate) = ... else { return; }`) an
explicit gate, which is cleaner than a separate bool-then-compact
pattern.
**Why `strum::IntoStaticStr` on the method enum?** Lets the variant
serialize to a `&'static str` for the JSON `details` field without a
manual `match` or adding `serde` derives.
### Fabro Details
<details>
<summary>Ran 9 stages in 30m 54s for $7.93</summary>
| Stage | Duration | Cost | Retries |
|---|---|---|---|
| start | 0s | – | 0 |
| toolchain | 2s | – | 0 |
| preflight_compile | 1m 52s | – | 0 |
| preflight_lint | 2m 6s | – | 0 |
| implement | 8m 11s | $3.47 | 0 |
| simplify_opus | 11m 7s | $3.53 | 0 |
| simplify_gpt | 2m 39s | $0.93 | 0 |
| verify | 4m 4s | – | 0 |
| fmt | 3s | – | 0 |
| **Total** | **30m 54s** | **$7.93** | **0** |
</details>
<details>
<summary>Ran <code>ImplementPlan.fabro</code> (12 nodes and 15
edges)</summary>
```dot
digraph ImplementPlan {
graph [
goal="Implement and simplify",
model_stylesheet="
* { model: claude-opus-4-7; }
"
]
rankdir=LR
start [shape=Mdiamond, label="Start"]
exit [shape=Msquare, label="Exit"]
toolchain [label="Toolchain", shape=parallelogram, script="command -v cargo >/dev/null || { curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y && sudo ln -sf $HOME/.cargo/bin/* /usr/local/bin/; }; cargo --version 2>&1", max_retries=0]
preflight_compile [label="Preflight Compile", shape=parallelogram, script="cargo check -q --workspace 2>&1", max_retries=0]
preflight_lint [label="Preflight Lint", shape=parallelogram, script="cargo +nightly-2026-04-14 clippy -q --workspace --all-targets -- -D warnings 2>&1", max_retries=0]
fix_lints [label="Fix Lints", prompt="The preflight lint step failed. Read the build output from context and fix all clippy lint warnings.", max_visits=3]
implement [label="Implement", prompt="Read the plan file referenced in the goal and implement every step. Make all the code changes described in the plan. Use red/green TDD.", model="gpt-55", reasoning_effort="xhigh"]
simplify_opus [label="Simplify (Opus)", prompt="@prompts/simplify.md"]
simplify_gpt [label="Simplify (GPT-55)", prompt="@prompts/simplify.md", model="gpt-55"]
verify [label="Verify", shape=parallelogram, script="cargo +nightly-2026-04-14 clippy -q --workspace --all-targets -- -D warnings 2>&1 && cargo nextest run --cargo-quiet --workspace --status-level fail 2>&1 && cargo dev docs refresh 2>&1 && cargo dev docs check 2>&1", goal_gate=true, retry_target="fixup"]
fixup [label="Fixup", prompt="The verify step failed. Read the build output from context and fix all clippy lint warnings, test failures, and generated docs errors.", max_visits=3]
fmt [label="Format", shape=parallelogram, script="cargo +nightly-2026-04-14 fmt --all 2>&1", max_retries=0]
start -> toolchain
toolchain -> preflight_compile [condition="outcome=succeeded"]
toolchain -> exit
preflight_compile -> preflight_lint [condition="outcome=succeeded"]
preflight_compile -> exit
preflight_lint -> implement [condition="outcome=succeeded"]
preflight_lint -> fix_lints
fix_lints -> preflight_lint
implement -> simplify_opus -> simplify_gpt -> verify
verify -> fmt [condition="outcome=succeeded"]
verify -> fixup
fixup -> verify
fmt -> exit
}
```
</details>
⚒️ Generated with [Fabro](https://fabro.sh)
---------
Co-authored-by: Fabro <noreply@fabro.sh>
|
||
|---|---|---|
| .. | ||
| build-support | ||
| fabro-acp | ||
| fabro-agent | ||
| fabro-api | ||
| fabro-auth | ||
| fabro-checkpoint | ||
| fabro-cli | ||
| fabro-client | ||
| fabro-config | ||
| fabro-core | ||
| fabro-dev | ||
| fabro-devcontainer | ||
| fabro-dump | ||
| fabro-github | ||
| fabro-graphviz | ||
| fabro-hooks | ||
| fabro-http | ||
| fabro-install | ||
| fabro-interview | ||
| fabro-llm | ||
| fabro-macros | ||
| fabro-manifest | ||
| fabro-mcp | ||
| fabro-mcp-server | ||
| fabro-model | ||
| fabro-oauth | ||
| fabro-options-metadata | ||
| fabro-proc | ||
| fabro-redact | ||
| fabro-sandbox | ||
| fabro-server | ||
| fabro-slack | ||
| fabro-spa | ||
| fabro-static | ||
| fabro-store | ||
| fabro-telemetry | ||
| fabro-template | ||
| fabro-test | ||
| fabro-tool | ||
| fabro-tracker | ||
| fabro-types | ||
| fabro-util | ||
| fabro-validate | ||
| fabro-vault | ||
| fabro-workflow | ||