chore(e2e): add detailed docs for e2e testing

[binoy14]

Description

Adds a comprehensive packages/@sanity/cli-e2e/README.md covering setup, globalSetup, the runCli() API (both spawn and PTY modes), CI workflows, debugging, and gotchas — none of which were documented before. Slims the writing-cli-e2e-tests skill to focus on test-writing patterns and cross-references the README for infrastructure details, so the two docs don't duplicate or drift.

Also touches up the skill: renames "Command tests" → "Unit tests" to match repo conventions, sharpens the selectOption description (literal substring vs. regex semantics), and drops a stale pnpm --filter @sanity/cli-e2e exec vitest run snippet in favor of the standard pnpm test:e2e.

What to review

• packages/@sanity/cli-e2e/README.md — new file; check that the runCli() API description, env helpers, CI section, and gotchas match the actual code in helpers/ and globalSetup.ts.
• .claude/skills/writing-cli-e2e-tests/SKILL.md — diff against main; the cross-references back to the README should land on real sections.
• AGENTS.md — single-line pointer update.

Testing

Docs-only — no behavior change, no changeset (per repo convention for docs). Verified all internal links resolve.

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Note

Low Risk
Docs-only changes that restructure and clarify how to run and write CLI e2e tests; no production code paths are modified.

Overview
Adds a comprehensive packages/@sanity/cli-e2e/README.md documenting local/CI setup, globalSetup behavior, the runCli() spawn vs PTY APIs, environment variables, debugging tips, and common gotchas.

Refactors .claude/skills/writing-cli-e2e-tests/SKILL.md to focus on test-writing patterns (planning, assertions, interactive selectOption semantics, unattended defaults) and cross-links to the new README for infrastructure details, and updates terminology from command tests to unit tests.

Updates AGENTS.md to point to the standard pnpm test:e2e commands for running individual e2e files/tests.

^{Reviewed by Cursor Bugbot for commit a60650e. Bugbot is set up for automated code reviews on this repo. Configure here.}

[binoy14]

This change is part of the following stack:

• chore(e2e): add detailed docs for e2e testing #1050 ◀

_{Change managed by git-spice.}

[claude]

Claude finished @binoy14's task in 2m 51s —— View job

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Review

• Read changed files
• Check for changeset requirement
• Provide review feedback

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Docs-only PR (.md files only) — no changeset needed, none included. ✓

No issues found. The README content is accurate against the implementation:

• pnpm test:e2e and pretest:e2e scripts verified to exist in root package.json
• globalSetup.ts packs exactly the three packages the README describes (@sanity/cli-core, @sanity/cli, create-sanity)
• getE2EDataset() is correctly documented as hardcoded to 'production' (not reading the SANITY_E2E_DATASET env var)
• selectOption string-escaping behavior ("literal substring match") matches the implementation at helpers/spawnPty.ts:98
• Default env vars (NO_UPDATE_NOTIFIER, SANITY_CLI_CONFIG_PATH, SANITY_AUTH_TOKEN) match runCli.ts
• .env.example has the same three vars as the Setup section documents

[github-actions]

📦 Bundle Stats — @sanity/cli

Compared against main (44a7ed9b)

@sanity/cli

Metric	Value	vs main (44a7ed9)
Internal (raw)	2.1 KB	-
Internal (gzip)	799 B	-
Bundled (raw)	10.94 MB	-
Bundled (gzip)	2.05 MB	-
Import time	847ms	+13ms, +1.6%

bin:sanity

Metric	Value	vs main (44a7ed9)
Internal (raw)	975 B	-
Internal (gzip)	460 B	-
Bundled (raw)	9.84 MB	-
Bundled (gzip)	1.77 MB	-
Import time	2.02s	+27ms, +1.4%

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• Import time regressions over 10% are flagged with ⚠️
• Sizes shown as raw / gzip 🗜️. Internal bytes = own code only. Total bytes = with all dependencies. Import time = Node.js cold-start median.

📦 Bundle Stats — @sanity/cli-core

Compared against main (44a7ed9b)

Metric	Value	vs main (44a7ed9)
Internal (raw)	93.1 KB	-
Internal (gzip)	21.9 KB	-
Bundled (raw)	21.60 MB	-
Bundled (gzip)	3.42 MB	-
Import time	799ms	-9ms, -1.1%

🗺️ View treemap · Artifacts

Details

• Import time regressions over 10% are flagged with ⚠️
• Sizes shown as raw / gzip 🗜️. Internal bytes = own code only. Total bytes = with all dependencies. Import time = Node.js cold-start median.

📦 Bundle Stats — create-sanity

Compared against main (44a7ed9b)

Metric	Value	vs main (44a7ed9)
Internal (raw)	976 B	-
Internal (gzip)	507 B	-
Bundled (raw)	50.7 KB	-
Bundled (gzip)	12.6 KB	-
Import time	❌ ChildProcess denied: node	-

Details

• Import time regressions over 10% are flagged with ⚠️
• Sizes shown as raw / gzip 🗜️. Internal bytes = own code only. Total bytes = with all dependencies. Import time = Node.js cold-start median.