docs(es/minifier): Clarify semantic preservation policy

[Donny/강동윤 (kdy1)]

Description:

Clarify the minifier implementation and review policy to prioritize correctness for common usage, performance, and maintainable code. Do not require additional defensive logic solely for monkey-patched globals or built-ins, unusual arguments.length reassignment, direct-eval bindings, or dynamic name resolution in with.

Keep ordinary lexical shadowing, side effects, and exceptions within the supported assumptions in scope. Require reviewers to demonstrate an impact on common usage or an explicit support contract for mandatory fixes. Align execution-test guidance with this policy without authorizing hidden failures or blanket removal of existing handling or tests.

The policy change is limited to the minifier AGENTS.md; a required patch changeset is included. No runtime code or tests change.

Validation:

• Passed: cargo fmt --all, git diff --check, cargo test -p swc_ecma_minifier, and minifier ./scripts/exec.sh.
• The crate tests exited successfully but emitted missing terser module errors from a helper script.
• cargo clippy --all --all-targets -- -D warnings failed on the existing unused noexec_mount_in function in crates/swc_native_addon/src/platform/unix.rs:117.

Related issue (if exists):

Motivated by the review discussions in #12343:

• refactor(es/minifier): Remove useless helpers #12343 (comment)
• refactor(es/minifier): Remove useless helpers #12343 (comment)
• refactor(es/minifier): Remove useless helpers #12343 (comment)

[changeset-bot]

🦋 Changeset detected

Latest commit: ae4cba3

The changes in this PR will be included in the next version bump.

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[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-11T12:06:31.942057Z	ae4cba3	PR opened
🔒 Security Review	✅ Completed 2026-09-11T12:07:01.314815Z	ae4cba3	PR opened

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[codspeed-hq]

Merging this PR will not alter performance

✅ 206 untouched benchmarks
⏩ 61 skipped benchmarks¹

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_{Comparing codex/minifier-semantic-policy (ae4cba3) with main (14bfa36)}

Footnotes

1. 61 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩