[None][docs] fix dead example links in legacy speculative-decoding

[imitater-dou]

Summary

• docs/source/legacy/advanced/speculative-decoding.md still linked to deleted example trees: examples/draft_target_model/README.md, examples/ngram/run_dtm_ngram.py, examples/medusa/README.md, examples/redrafter/README.md, examples/eagle/README.md, and examples/lookahead/README.md (all 404 on main).
• Retarget Draft/Target and NGram how-tos to docs/source/features/speculative-decoding.md (and keep the live examples/ngram/README.md pointer).
• Mark Medusa / Lookahead / ReDrafter / legacy EAGLE example trees as removed; point readers at the current speculative-decoding feature doc. Live telemetry speculative_config.decoding_type is AUTO, DFlash, DSpark, Draft_Target, Eagle3, Eagle, MTP, NGram, PARD, SA, SaveState, User_Provided (no Medusa/Lookahead).

Test plan

• Confirmed 404 for the six deleted paths on HEAD 07a58bd
• Confirmed examples/ngram/README.md still exists
• Confirmed current feature doc has no Medusa/Lookahead sections
• Diff limited to one legacy docs file

Signed-off-by: ADou ikun3.1415927@gmail.com

Dev Engineer Review

• Updated legacy speculative-decoding documentation links.
• Redirected Draft/Target, NGram, Medusa, Lookahead, ReDrafter, and EAGLE guidance to current documentation.
• Retained the live examples/ngram/README.md link.
• Redirected disaggregated-serving guidance to disagg-serving.md.
• Marked removed decoding examples and documented the EAGLE3 draft_vocab_size default and warning.
• No source-code, API, configuration, or runtime behavior changes.

Per-File QA Perspective

• docs/source/legacy/advanced/speculative-decoding.md: Verify that redirected links resolve, removed examples are clearly identified, the NGram README remains valid, and the EAGLE3 guidance is accurate. No executable behavior changes require regression testing.

QA Engineer Review

No test changes.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Enterprise

Run ID: 09c8a266-18b1-40b0-b1ed-2f152f02ca14

📥 Commits

Reviewing files that changed from the base of the PR and between 8a45f28 and d5c19c4.

📒 Files selected for processing (1)

• docs/source/legacy/advanced/speculative-decoding.md

🚧 Files skipped from review as they are similar to previous changes (1)

• docs/source/legacy/advanced/speculative-decoding.md

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Walkthrough

The legacy speculative decoding guide now links to current documentation, identifies removed examples and decoding types, and documents EAGLE3 draft_vocab_size behavior.

Changes

Speculative decoding documentation

Layer / File(s)	Summary
Legacy guidance and current links docs/source/legacy/advanced/speculative-decoding.md	The guide links Draft/Target, NGram, ReDrafter, EAGLE, Medusa, and Lookahead references to current documentation. It records removed examples and decoding types and corrects the EAGLE3 disaggregated-serving link.
EAGLE3 configuration note docs/source/legacy/advanced/speculative-decoding.md	The guide states that omitted draft_vocab_size defaults to vocab_size with a warning. Different draft vocabularies require explicit configuration.

Priority: ⬇️ Low

Estimated code review effort: 1 (Trivial) | ~2 minutes

Merge Risk: ⚪ Minimal · up to d5c19

The legacy speculative-decoding guide redirects obsolete example links to current documentation and marks removed content without any identified merge-readiness risk.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely identifies the documentation fix for dead links in the legacy speculative-decoding page. The [docs] type is understandable, although the template lists [doc] as the sta…
Description check	✅ Passed	The description explains the problem, the solution, and the verification steps. It includes relevant test coverage, but it omits the repository's standard Description heading and PR Checklist section.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
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.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[brnguyen2]

Approving — the comments below are optional touch-ups, not blockers.

Content checks out: examples/{draft_target_model,medusa,redrafter,eagle,lookahead} and examples/ngram/run_dtm_ngram.py are gone, examples/ngram/README.md is present, and the Draft/Target, NGram, and EAGLE 3 sections you point at exist in docs/source/features/speculative-decoding.md (which has no Medusa/Lookahead sections).

One nit beyond the inline: these could be repo-relative Markdown links (e.g. ../../features/speculative-decoding.md) so they resolve within the built docs instead of bouncing readers to GitHub. The file already used absolute URLs, so not a blocker.

[brnguyen2]

The trailing newline at end of file was dropped (the base version had one). end-of-file-fixer in .pre-commit-config.yaml will rewrite this — run pre-commit run --files docs/source/legacy/advanced/speculative-decoding.md and re-commit so CI's pre-commit check passes.