refactor(markdown-parser): replace remaining magic numbers with named constants

[jfmcdowell]

Note

AI Assistance Disclosure: This PR was developed with assistance from Claude Code.

Summary

Follow-up to #9228 — three hardcoded literals were missed before that PR merged.

• count_leading_indent in parser.rs: 4 → TAB_STOP_SPACES
• consume_indent_prefix in syntax/mod.rs: 4 → TAB_STOP_SPACES
• render_fenced_code_block in to_html.rs: .min(3) → .min(MAX_BLOCK_PREFIX_INDENT)

No user-facing behavior change. All 652 CommonMark conformance tests pass.

Test Plan

• just test-markdown-conformance — 652/652 pass, 100% coverage
• cargo check -p biome_markdown_parser — compiles cleanly

Docs

N/A — internal refactor only.

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⚠️ No Changeset found

Latest commit: ecf0df8

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📥 Commits

Reviewing files that changed from the base of the PR and between 59e33fb and ecf0df8.

📒 Files selected for processing (3)

• crates/biome_markdown_parser/src/parser.rs
• crates/biome_markdown_parser/src/syntax/mod.rs
• crates/biome_markdown_parser/src/to_html.rs

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Walkthrough

This pull request replaces hard-coded magic numbers with named constants across the markdown parser. Specifically, the value 4 is replaced with TAB_STOP_SPACES in indentation counting logic, and the value 3 is replaced with MAX_BLOCK_PREFIX_INDENT for fence indentation calculations. Changes span three files with no modifications to public APIs or control flow logic.

Possibly related PRs

• refactor(markdown-parser): extract magic numbers to named constants #9228: Replaces the same hard-coded indentation/tab constants (3 and 4) with MAX_BLOCK_PREFIX_INDENT and TAB_STOP_SPACES in identical files, suggesting these are complementary refactors.
• refactor(markdown-parser): promote pre-marker indent to explicit CST #9224: Introduces MAX_BLOCK_PREFIX_INDENT and refactors quote pre-marker indentation handling, indicating foundational work on indentation constant definitions and parser handling.

Suggested reviewers

• dyc3
• ematipico

🚥 Pre-merge checks | ✅ 2

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarises the main change: replacing magic numbers with named constants across the markdown parser.
Description check	✅ Passed	The description clearly relates to the changeset, explaining the specific replacements made and providing test results confirming no behaviour changes.

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[jfmcdowell]

@ematipico missed a few