feat: reduce AI context token consumption by collapsing successful bu…

[killme2008]

…ilds, using tail-biased truncation, and relaxing verbatim output instructions

[killme2008]

@copilot review it

[Copilot]

@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.

[Copilot]

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.CollapseSuccessful to 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 + 1 entries when truncation occurs because it adds an omission marker in addition to head+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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[Copilot]

Pull request overview

Copilot reviewed 10 out of 10 changed files in this pull request and generated 3 comments.

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