See changed lines on GitHub

diffdevil for GitHub adds a personal Changed view to pull requests you can already read. It requires no repository workflow, App installation or label-write permission. Start by opening one PR, reading its aggregate result, and then inspecting a file’s evidence.

Install or update the extension

Use Chrome 120 or newer for the Manifest V3 source build. Do not infer support for Firefox, Enterprise GitHub hosts or incognito from it. Use the extension product page for release availability. A Store listing must actually exist before it is an installation route.

For the available source route, use a diffdevil checkout and Node.js 22.12 or newer. At its root run:

npm ci --ignore-scripts
npm run extension:dev

The complete unpacked build is artifacts/browser-extension/unpacked/. Open chrome://extensions, enable Developer mode, choose Load unpacked, and select that directory. If your organization forbids unpacked extensions, use its approved installation process rather than bypassing the restriction.

After rebuilding to update, use Reload on the extension’s card and reload the GitHub tab too. A newly written directory does not replace the code already running in an open page. The canonical build instructions own the source-build requirements and qualification details.

Open a whole pull request

Open a PR at https://github.com/OWNER/REPO/pull/NUMBER that your browser can read. The aggregate Changed projection follows the whole PR across its Conversation, Commits, Checks and Files changed tabs.

Look for Changed beside GitHub’s native statistics. GitHub’s additions and deletions remain the raw view; Changed counts replacements once within their edit blocks. For example, the complete local teaching patch and the default size@1 policy produce 10 Changed, 16 raw churn, band xs. The extension uses that same report semantics, not a second browser counting formula.

Click Changed to open the nonmodal detail panel. Inspect the acquired head/base, evidence standing, file records and policy provenance. Close it with its close control or Escape. A displayed count belongs to those revisions, not indefinitely to the PR number.

When evidence is bounded, unknown or unmeasurable, retain that standing. A range is not an approximate point estimate, and missing acquisition is not zero Changed. Changed lines and raw churn explains the components; Evidence and uncertainty explains the limits.

Inspect a file, then the policy

On the whole PR’s Files changed tab, inspect one file’s Changed result and raw additions/deletions. Per-file projection is deliberately absent from commit-only or narrowed comparison routes, where whole-PR data would describe the wrong comparison.

A local size pill is the extension’s classification under its effective policy. It is not a label applied to GitHub, a managed-App check, or evidence that repository automation ran. Even an exact count can have different bands under different policies.

Policy provenance explains which personal settings, trusted repository-base policy and explicit personal repository override contributed. An inaccessible policy is not the same as an absent policy. Invalid or unavailable configuration remains visible rather than silently producing a different classification; usable facts need not disappear with it.

Find one setting

Open the extension from its browser-toolbar icon to reach settings. Search for the setting you need instead of browsing a long inventory. Search can reveal an Advanced setting without permanently switching every setting to Advanced mode.

The source-defined deep links include #display.brandIcon and #policy.advancedYaml on the extension’s own options page. They reveal and focus the selected control. These are extension-local fragments, not routes on the product website. Use Pause this repository in the report or Settings to stop augmentation for this repository in your browser; Resume restores it without changing repository automation or deleting cached data.

Personal settings do not change repository automation. Import or export policy deliberately, and inspect errors before saving. Invalid policy must not replace the last valid settings. The deeper extension guide covers settings, origins, caches and reset behavior.

Keep the local boundary clear

Analysis runs in the browser extension. It does not submit a PR to a diffdevil analysis service, accept a personal access token, or apply labels/comments. A native label-picker handoff still leaves selecting the label to you; opening that picker is not an automated write.

Reports and trusted-policy caches can contain private paths and revisions. Small preferences may use browser sync, while advanced policy, repository overrides and pause choices stay local. Treat a complete settings export differently from a redacted support snapshot. Read the extension privacy source and Security and data before sharing diagnostic material.

Recover a missing or stale result

Nothing appeared: verify that the extension is enabled, that this is a supported whole-PR route, and that the page has been reloaded after installation. A GitHub access failure is not fixed by changing size thresholds.

The numbers describe an older head: reload or reacquire the PR and inspect the new source identity. Do not carry a cached number forward without its revision. Rebuilding the extension also requires reloading both extension and tab.

Facts appear but classification does not: inspect the selected policy’s origin and diagnostics. Repair the configuration or the access problem it names; do not reinterpret failure as “no repository policy.”

Only a file-level result is absent: first check whether you are viewing a single commit or narrowed comparison. On a supported full-PR view, inspect acquisition and evidence rather than treating a missing row as unchanged.

A large PR is only partly measured: automatic acquisition has a configurable file limit, initially 150. Open a file or choose Analyze remaining files for explicit continuation. If GitHub declined a requested file’s lines, inspect the reason and use Ask GitHub again when you want another attempt. “Not confirmed” instead means the cached comparison remains visible while current GitHub freshness could not be established.

After repair, open the detail panel again and confirm the intended comparison and policy. Continue with diffdevil for GitHub for the complete operating guide.