feat: reduce AI context token consumption by collapsing successful bu…#2
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killme2008 merged 3 commits intomainfrom Feb 7, 2026
Merged
feat: reduce AI context token consumption by collapsing successful bu…#2killme2008 merged 3 commits intomainfrom
killme2008 merged 3 commits intomainfrom
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…ilds, using tail-biased truncation, and relaxing verbatim output instructions Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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@copilot review it |
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@killme2008 I've opened a new pull request, #3, to work on those changes. Once the pull request is ready, I'll request review from you. |
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Pull request overview
This PR reduces AI context usage from devtap drains by collapsing successful runs into a single summary line, biasing truncation toward the tail of logs, and relaxing “verbatim output” instructions for successful builds.
Changes:
- Add
mcp.CollapseSuccessfulto replace successful run output (exit code 0) with a single-line omission summary. - Switch message truncation to use tail-biased truncation (
TruncateWithRatio(..., 0.8)) to preserve end-of-log errors. - Update MCP/tooling instructions/docs to acknowledge successes briefly and only show verbatim output on failures.
Reviewed changes
Copilot reviewed 10 out of 10 changed files in this pull request and generated 1 comment.
Show a summary per file
| File | Description |
|---|---|
| skills/devtap-get-build-errors/SKILL.md | Updates skill guidance to avoid repeating successful output and keep failures verbatim. |
| internal/mcp/truncate.go | Uses tail-biased truncation for per-message line truncation. |
| internal/mcp/server.go | Updates tool description and collapses successful runs before truncation/formatting. |
| internal/mcp/collapse.go | Implements collapsing of successful runs into a single summary line. |
| internal/mcp/collapse_test.go | Adds unit tests covering collapse behavior across multiple run/tag scenarios. |
| internal/filter/truncate.go | Introduces TruncateWithRatio and redefines Truncate as a 50/50 wrapper. |
| internal/filter/truncate_test.go | Adds tests for tail-biased truncation and edge cases. |
| internal/adapter/instructions.go | Updates injected instruction block to not repeat successful output. |
| cmd/devtap/drain.go | Collapses successful runs before truncation in CLI drain paths. |
| CLAUDE.md | Updates documented output expectations for successful vs failed builds. |
Comments suppressed due to low confidence (1)
internal/filter/truncate.go:50
- TruncateWithRatio can return
maxLines + 1entries when truncation occurs because it adds an omission marker in addition tohead+tail==maxLines. This means callers like mcp.TruncateMessages can exceed their overall line budget (and may clear later messages earlier than intended). If maxLines is meant to be a hard cap, adjust the algorithm so the omission marker is included in the budget (e.g., reserve 1 line for the marker and use head+tail=maxLines-1 when truncating).
omitted := len(lines) - head - tail
result := make([]string, 0, head+1+tail)
result = append(result, lines[:head]...)
result = append(result, fmt.Sprintf("... (%d lines omitted)", omitted))
result = append(result, lines[len(lines)-tail:]...)
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Signed-off-by: Dennis Zhuang <killme2008@gmail.com>
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Pull request overview
Copilot reviewed 10 out of 10 changed files in this pull request and generated 3 comments.
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Signed-off-by: Dennis Zhuang <killme2008@gmail.com>
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…ilds, using tail-biased truncation, and relaxing verbatim output instructions