feat(agents): add diff and open commands (3/8)

[VaibhavAcharya]

Summary

Linear: https://linear.app/netlify/issue/EX-2195

Part 3 of the agents CLI revamp split. Adds two read-only commands.

• agents:diff prints the change set an agent run produced. Supports --session, --cumulative, pagination, and --no-strip-binary to keep raw binary patches (stripped by default).
• agents:open opens the run's preview, dashboard, or pull request in the browser. Honors NETLIFY_WEB_UI so links work on staging.

$ netlify agents:open <id> dashboard
Opening https://app.netlify.com/projects/another-astro-starter/agent-runs/69e766451314e00fad873557

$ netlify agents:open <id> pr   # when a PR is being created
A pull request is being created. Try again in a moment.

$ netlify agents:open <id> bogus
Error: Invalid target "bogus". Choose one of: preview, dashboard, pr

Stacked on the existing-commands PR.

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[coderabbitai]

📝 Walkthrough

Walkthrough

This PR adds two new Netlify CLI subcommands for managing agent runs. agents:open opens agent run destinations (preview deployments, dashboard, or pull requests) in a browser with conditional fallback behavior. agents:diff fetches and displays code diffs produced by agent runs, supporting both session-based and paginated diff modes with color formatting and pagination footers. The implementation includes CLI command registration, handler functions with API integration and error handling, comprehensive integration tests covering all code paths, and updated documentation.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main change: adding two new CLI commands (diff and open) to the agents command group.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description check	✅ Passed	The PR description clearly outlines two new commands (agents:diff and agents:open) with specific functionality, flags, and examples that directly correspond to the changeset.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch agent/cli/pr8237-cmd-diff-open

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_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[VaibhavAcharya]

@coderabbitai review

[coderabbitai]

✅ Actions performed

Review triggered.

Note: CodeRabbit is an incremental review system and does not re-review already reviewed commits. This command is applicable only when automatic reviews are paused.

[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@src/commands/agents/agents-open.ts`:
- Around line 60-67: The messages in agents-open referencing a non-existent CLI
command `netlify agents:pr` are dead-ends; update the user-facing strings in
src/commands/agents/agents-open.ts (the block that checks runner.pr_error and
the subsequent "No pull request exists" branch using runner) to point to the
correct invocation `netlify agents:open <id> pr` (or to the actual command you
choose to implement), so users are given a valid CLI instruction; ensure both
the retry and create messages use `netlify agents:open ${id} pr` (or replace
with the name of a newly added agents:pr command if you implement that
endpoint).

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: e3567f08-9402-45bd-b650-7d5a9d1369a9

📥 Commits

Reviewing files that changed from the base of the PR and between c47c842 and 3220465.

📒 Files selected for processing (7)

• docs/commands/agents.md
• docs/index.md
• src/commands/agents/agents-diff.ts
• src/commands/agents/agents-open.ts
• src/commands/agents/agents.ts
• tests/integration/commands/agents/agents-diff.test.ts
• tests/integration/commands/agents/agents-open.test.ts

[VaibhavAcharya]

Link EX-2195