What is stale-base-pr-silently-reverts-upstream-content?

A guide for detecting when merging one pull request silently removes content from another. A pull request is a proposed code change, and a squash merge combines its commits into one.

Use it to investigate parallel pull requests that edit the same files, compare changes after a squash merge, and recover content that was unintentionally reverted.

It addresses a version-control problem where an older branch can overwrite newer upstream edits even though the merge and automated checks succeed.

stale-base-pr-silently-reverts-upstream-content

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent

npx skills add wan-huiyan/agent-traffic-control --skill stale-base-pr-silently-reverts-upstream-content

Clone the repo

git clone --depth 1 https://github.com/wan-huiyan/agent-traffic-control

Made for: Claude Code.

Or install agent-traffic-control, the plugin that ships this one along with the rest of its 107 skills.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/wan-huiyan/agent-traffic-control/stale-base-pr-silently-reverts-upstream-content/github.svg)](https://agentmods.dev/skills/wan-huiyan/agent-traffic-control/stale-base-pr-silently-reverts-upstream-content)

Your own site

<a href="https://agentmods.dev/skills/wan-huiyan/agent-traffic-control/stale-base-pr-silently-reverts-upstream-content"><img src="https://agentmods.dev/badge/skills/wan-huiyan/agent-traffic-control/stale-base-pr-silently-reverts-upstream-content/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/wan-huiyan/agent-traffic-control/stale-base-pr-silently-reverts-upstream-content"><img src="https://agentmods.dev/badge/skills/wan-huiyan/agent-traffic-control/stale-base-pr-silently-reverts-upstream-content.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 391 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 4,940 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00391	$0.04940
Opus 5	$0.00196	$0.02470
Sonnet 5	$0.00078	$0.00988
Haiku 4.5	$0.00039	$0.00494

Measured 7d ago against content hash 32aa9825a516, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

stale-base-pr-silently-reverts-upstream-content scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 7d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

plugins/agent-traffic-control/skills/stale-base-pr-silently-reverts-upstream-content/SKILL.md · 403 lines

How it starts

The opening of the file, as written. The whole thing — 403 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Stale-Base PR Silently Reverts Upstream Content via Textual Overlap

Problem

You ship PR A: updates 8 specific lines in templates/foo.html with new numbers (50% vs 6%, n=117, etc.). PR A merges cleanly. CI green.

In parallel, PR B was opened against origin/main BEFORE PR A merged. PR B rewrites copy in the same file for language polish — touching the same 8 lines, but with the OLD numbers (because that's what PR B's base showed). PR B's body claims "all numbers preserved."

PR B rebases / gh pr merge --squashs after PR A. Git's 3-way merge runs:

Base (common ancestor): old text + OLD numbers
Main side (post-PR-A): old text + NEW numbers ← PR A's contribution
PR B side: rewritten text + OLD numbers ← PR B's contribution

For lines where PR B's rewrite spans the same text PR A edited, the 3-way merge sees PR B as the "winning" branch-side and takes PR B's version wholesale. PR A's numbers silently disappear from those lines. Other files PR A touched but PR B didn't (app.py, intelligence_findings.js, library_findings.html) keep PR A's numbers intact.

Result: a train-serve / display-vs-backend mismatch that no PR diff, no CI signal, and no merge conflict flagged. PR B's author was honest — the numbers WERE preserved against THEIR base. The regression is invisible until someone audits the post-merge main against PR A's intended diff.

Context / Trigger Conditions

All of these typically hold:

Two PRs open in parallel on the same file(s) — one updates values (numbers, names, IDs, configuration), the other polishes copy / language / structure.
Value-refresh PR (A) merges first. Often a data-correctness or recalibration PR.
Language-polish PR (B) is based on pre-A main. Detect via:
```
gh pr view <B> --json baseRefOid
# vs.
gh pr view <A> --json mergeCommit
```
If B's base predates A's merge commit, B has a stale base.
PR B's body claims "X preserved" — true against its base, but the base is stale. Common phrases: "all numbers preserved", "zero logic changes", "preserves all findings".
No merge conflict on gh pr merge: git resolves the textual overlap silently. Both PRs show mergeable: MERGEABLE, CI on both is green.
Post-merge: only files BOTH PRs touched are affected. Files only PR A touched stay correct (no overlap to resolve). This produces the tell-tale train-serve mismatch where backend constants match PR A's intent but displayed copy in the overlapped template doesn't.

Read the full file on GitHub · 403 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

7d ago First seen · 403 lines · 391 tokens per session scan A 32aa9825a516

Subscribe to this mod's changes

stale-base-pr-silently-reverts-upstream-content is a skill published in the GitHub repository wan-huiyan/agent-traffic-control (3 stars, last pushed today), licensed MIT. It adds 391 tokens to every session and 4,940 once invoked, about $0.0020 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-05.

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