security: bind .html4ignore read to NOFOLLOW_LINKS at open time

[seonghobae]

Current exact authority

• protected base: master@728f0f33323e43573d6664209891099502827d5d
• exact head: 5c29d6c8d48504720a0add35136ceee26a6b5f57
• ancestry: ahead 2 / behind 0; merge base is exact protected master
• effective protected-base delta: src/main/kotlin/html4tree/main.kt only
• branch-specific .jules/sentinel.md doctrine was restored byte-for-byte to protected authority
• lifecycle: Draft; realistic race/recovery and exact-head hosted evidence remain incomplete

Valid finding

The protected implementation checks isFile, isSymbolicLink, readability, and size before later calling File.useLines. A final-component path can change after those checks. This branch changes the time-of-use open to Files.newInputStream(path, READ, NOFOLLOW_LINKS), so a final-component symlink is not followed by that open. Java NIO defines LinkOption.NOFOLLOW_LINKS as an OpenOption whose contract is not to follow symbolic links.

The original PR overclaimed full TOCTOU closure and verified security without a deterministic swap case. No branch test currently proves a replacement between pre-check and open, and an open-time IOException currently escapes process_ignore_file/crawl_directories, which is fail-closed for publication but can terminate the wider crawl instead of applying a bounded per-directory policy failure.

Sibling #629 owns a complementary delta: a declared-but-invalid policy becomes IgnoreFileReadException, the crawler skips publication of that directory, and current successor 466c214dd7b358e77d411514165ad72562871bcf includes a deterministic propagation test. #629, however, still uses File.useLines after the pre-check and therefore does not by itself bind the actual open to NOFOLLOW_LINKS. Neither PR fully supersedes the other yet; do not close either as a duplicate.

GREEN acceptance

Produce one normal descendant/successor that preserves both valid semantic deltas: (1) a time-of-use open that cannot follow a final-component symlink, and (2) typed fail-closed policy-read handling that prevents publication/child traversal for the affected directory without silently treating policy failure as no policy. Add deterministic seams/fixtures for open failure and replacement semantics rather than a timing-dependent background race. Preserve the existing size/line/pattern limits and default-sensitive exclusions. Then run one unchanged exact head through CI/security/SAST/CodeQL. Only after byte/semantic/test inheritance is verified may one sibling be closed as fully superseded.

Fresh current-head workflows are non-terminal: CI 33992368306, Security Scan 33992368293, SAST Semgrep 33992368415, and CodeQL PR 33992368282 are queued/pending. Predecessor results do not transfer.

No force-push, destructive rebase, self-approval, suppression, or security-severity inflation. Keep Draft until the combined causal boundary and exact-head evidence exist.

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