Add bounded GitHub file excerpt MCP wrapper by Copilot · Pull Request #50684 · github/gh-aw

Copilot · 2026-08-05T19:50:01Z

GitHub MCP get_file_contents only returns whole files, which makes large README-style reads expensive when agents need only a small section. This adds a reusable bounded-read wrapper for workflows that need targeted file context.

MCP script wrapper
- Adds get_file_contents_excerpt to shared/github-mcp-pagination-wrappers.md.
- Supports byteOffset, maxBytes, startLine, and endLine.
- Uses gh api with a byte Range header, then optionally filters lines before returning JSON.
Workflow adoption
- Updates the GitHub MCP structural analysis workflow to sample repository file content through the bounded wrapper instead of full get_file_contents.
- Recompiles affected lock files.
Coverage
- Adds focused tests that verify the shared wrapper schema and exercise bounded output with a mocked gh api response.

Example:

get_file_contents_excerpt:
  owner: github
  repo: gh-aw
  path: README.md
  ref: main
  maxBytes: 4000
  startLine: 1
  endLine: 80

Fixes [deep-report] MCP get_file_contents has no excerpt/range-read mode — full-file reads waste ~4,500 tokens on large files #50594

Run: https://github.com/github/gh-aw/actions/runs/31052246569> Generated by 👨‍🍳 PR Sous Chef · gpt54 · 5.39 AIC · ⌖ 7.13 AIC · ⊞ 8.3K · ◷

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Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

Copilot

🟡 Changes recommended

Cross-repository defaults, special-character paths, and end-only line ranges currently produce incorrect behavior.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

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Pull request overview

Adds a bounded GitHub file-content wrapper to reduce unnecessary MCP response tokens.

Changes:

Adds byte- and line-bounded file excerpts.
Adopts the wrapper in structural analysis.
Adds focused wrapper tests and recompiles workflows.

File summaries

File	Description
`.github/workflows/shared/github-mcp-pagination-wrappers.md`	Defines and documents the wrapper.
`.github/workflows/github-mcp-structural-analysis.md`	Uses bounded excerpts.
`.github/workflows/github-mcp-structural-analysis.lock.yml`	Recompiled workflow.
`.github/workflows/deep-report.lock.yml`	Recompiled imported wrapper.
`pkg/workflow/mcp_scripts_shared_wrappers_test.go`	Tests schema and bounded output.

Review details

Files reviewed: 5/5 changed files
Comments generated: 3
Review effort level: Balanced

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+      OWNER="${INPUT_OWNER:-}"
+      REPO="${INPUT_REPO:-}"
+      PATH_IN_REPO="${INPUT_PATH:-}"
+      REF="${INPUT_REF:-${GITHUB_SHA:-}}"


+      BYTE_END=$((BYTE_OFFSET + MAX_BYTES))
+      export OWNER REPO PATH_IN_REPO REF BYTE_OFFSET MAX_BYTES START_LINE END_LINE
+      gh api \
+        --method GET \
+        -H "Accept: application/vnd.github.raw" \
+        -H "Range: bytes=${BYTE_OFFSET}-${BYTE_END}" \
+        "repos/${OWNER}/${REPO}/contents/${PATH_IN_REPO}" \
+        -f "ref=${REF}" > "$RAW_FILE"


+      if start_line:
+        line_start = int(start_line)
+        line_end = int(end_line) if end_line else line_start + 99
+        lines = text.splitlines(keepends=True)
+        text = "".join(lines[line_start - 1:line_end])


gh-aw-bot · 2026-08-05T22:24:15Z

@copilot please review the latest PR feedback, refresh this branch if it is behind main, then run the pr-finisher skill and push any follow-up fixes.

failed checks:
- impacted-go-tests: https://github.com/github/gh-aw/actions/runs/31042085263/job/92455252621
- Unit tests (A-C): https://github.com/github/gh-aw/actions/runs/31042085263/job/92455573866

Run: https://github.com/github/gh-aw/actions/runs/31052246569

Generated by PR Sous Chef.

Generated by 👨‍🍳 PR Sous Chef · gpt54 · 5.39 AIC · ⌖ 7.13 AIC · ⊞ 8.3K · ◷
_{Comment /souschef to run again}

…line filtering; sort actions-lock containers Co-authored-by: gh-aw-bot <259018956+gh-aw-bot@users.noreply.github.com>

Copilot · 2026-08-05T22:32:23Z

@copilot please review the latest PR feedback, refresh this branch if it is behind main, then run the pr-finisher skill and push any follow-up fixes.

failed checks:...

Addressed all three review issues and fixed the CI failures:

Cross-repo ref default — GITHUB_SHA is now only used when ${OWNER}/${REPO} matches ${GITHUB_REPOSITORY}; otherwise the wrapper falls through to the existing gh repo view default-branch lookup.
URL encoding — PATH_IN_REPO is now percent-encoded via Python's urllib.parse.quote (preserving / separators) before being inserted into the gh api URL.
endLine without startLine — the Python filtering block now triggers when either start_line or end_line is set, defaulting start_line to 1 when omitted, so endLine-only inputs correctly return lines 1–N.
CI fix — sorted the containers field in .github/aw/actions-lock.json to fix TestActionsLockJSONFieldsAreSorted (the new container added in the initial commit landed at the end instead of in lexicographic order).

Initial plan

9a90e68

Copilot AI assigned Copilot and pelikhan Aug 5, 2026

Copilot started work on behalf of pelikhan August 5, 2026 19:50 View session

Copilot AI linked an issue Aug 5, 2026 that may be closed by this pull request

[deep-report] MCP get_file_contents has no excerpt/range-read mode — full-file reads waste ~4,500 tokens on large files #50594

Open

Add GitHub file excerpt MCP wrapper

0829bd2

Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

Copilot AI changed the title ~~[WIP] Add excerpt and range-read mode to MCP get_file_contents~~ Add bounded GitHub file excerpt MCP wrapper Aug 5, 2026

Copilot finished work on behalf of pelikhan August 5, 2026 20:05

Copilot AI requested a review from pelikhan August 5, 2026 20:05

pelikhan marked this pull request as ready for review August 5, 2026 21:45

Copilot AI balanced review requested due to automatic review settings August 5, 2026 21:45

Copilot started reviewing on behalf of pelikhan August 5, 2026 21:46 View session

Copilot AI reviewed Aug 5, 2026

View reviewed changes

github-actions Bot mentioned this pull request Aug 5, 2026

[pr-sous-chef] pr-sous-chef run report #50440

Closed

Copilot started work on behalf of gh-aw-bot August 5, 2026 22:24 View session

Fix wrapper bugs: ref cross-repo default, URL encoding, endLine-only …

233a9d6

…line filtering; sort actions-lock containers Co-authored-by: gh-aw-bot <259018956+gh-aw-bot@users.noreply.github.com>

Copilot finished work on behalf of gh-aw-bot August 5, 2026 22:32

Copilot AI requested a review from gh-aw-bot August 5, 2026 22:32

pelikhan closed this Aug 5, 2026

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Add bounded GitHub file excerpt MCP wrapper - #50684

Add bounded GitHub file excerpt MCP wrapper#50684
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