docs-comments-cleanup: remove historical code-reduction report

[konard]

Summary

This PR reduces documentation surface by deleting the historical code_reduction_report.md while preserving every canonical-doc invariant and all kernel behavior.

Linked issue

Contributes to #386 (Packet B — reduce duplicated docs/comments).

Change class

• docs-comments-cleanup

Target surface

• docs/code_reduction_report.md (deleted)
• docs/index.md (removed the supporting-docs row pointing at it)
• .gitkeep (bootstrap placeholder removed now that the branch carries a real change)

Non-goals

• No code, kernel, or generated (single_include/**) changes.
• No governance or release changes (CHANGELOG.md keeps its historical mention as an immutable release record).
• No new documents and no rewrites of remaining docs.
• No removal of any canonical document — the canonical set in repo-policy.json / docs/index.md is untouched.

Surface delta

• New files: 0
• Deleted files: 2 (docs/code_reduction_report.md, .gitkeep)
• Net lines: −102
• Public API change: none
• Generated surface touched: no
• Docs touched: yes (only docs)
• Governance touched: no

Complexity delta

docs/code_reduction_report.md is a one-off process/metrics report for the closed issue #254. It is exactly the class of "phase logs, process notes, or AI progress reports" the issue forbids adding and Packet B asks to remove as historical/process noise. Under docs/deletion_policy.md it is a delete candidate (superseded historical record, fully preserved in Git history and in the CHANGELOG.md entry). Removing it makes the documentation set smaller and sharpens the canonical reading route without leaving a dangling navigation link.

Preserved invariants

• Canonical document set (repo-policy.json paths.canonical_docs ⟺ docs/index.md "Canonical Documents") remains byte-for-byte consistent.
• No kernel, allocator, forest, verify/repair, or layout behavior is touched.
• Requirements traceability and catalog remain consistent.

Verification

bash    scripts/check-docs-consistency.sh          # OK
bash    scripts/check-repo-guard-rollout.sh         # OK
python3 scripts/check-requirements-traceability.py  # OK
python3 scripts/check-requirements-catalog.py       # OK (0 warnings)
git diff --stat origin/main...HEAD                  # 2 files, 102 deletions, 0 insertions

Only the historical CHANGELOG.md mention of the report remains (a non-link backtick reference recording when the doc was originally added); CHANGELOG.md is release-owned and intentionally not modified.

Reviewer checklist

• One PR = one reason for change
• No mixed surface bucket
• No upper-layer semantics added
• No convenience growth
• No undocumented surface debt
• No generated churn unless explicitly mechanical
• Net repository surface is non-positive or justified

change_type: docs-comments-cleanup
scope:
  - docs/
budgets:
  max_new_files: 0
  max_new_docs: 0
must_touch: []
must_not_touch:
  - repo-policy.json
  - include/
  - single_include/
  - CHANGELOG.md
expected_effects:
  - Delete the historical docs/code_reduction_report.md process report
  - Remove its row from docs/index.md supporting-docs table

Fixes #386

[konard]

Working session summary

Done. Here's a summary of the work.

What I did

For the coordinating issue #386 (an AI-swarm cleanup that requires one small, atomic, surface-reducing PR), I picked Packet B — reduce duplicated docs/comments and executed the cleanest, lowest-risk target available.

The change

Deleted docs/code_reduction_report.md — a one-off process/metrics report tied to the long-closed issue #254. It is precisely the class of "phase logs, process notes, or AI progress reports" the issue forbids adding and asks to remove as historical noise. Under docs/deletion_policy.md it qualifies as delete (a superseded historical record, fully preserved in Git history and in the CHANGELOG.md entry). I also removed its row from the docs/index.md supporting-docs table, and dropped the bootstrap .gitkeep placeholder so the PR is purely docs with zero new files.

Why this target (and why not others)

• Packet A (remove .inc shards) would force editing the kernel header and many doc cross-references (mutation_ordering.md, core_invariants.md reference forest_domain_mixin.inc:NNN line numbers) — a mixed-surface PR the issue explicitly rejects.
• Kernel packets (C/D) trigger the include/** → tests/** co-change rule and require full C++ build verification.
• A docs-only deletion is single-surface, net-negative, behavior-neutral, and skips the build CI entirely (paths-ignore: **/*.md).

Surface delta

• New files: 0 · Deleted files: 2 · Net lines: −102 · Public API: unchanged · Generated/governance/release: untouched · Canonical doc set: byte-for-byte consistent.

Verification

• check-docs-consistency.sh, check-repo-guard-rollout.sh, check-requirements-traceability.py, check-requirements-catalog.py — all OK locally.
• CI on the PR: Docs consistency ✅, Version consistency ✅, repo-guard blocking check ✅ (validating the docs-comments-cleanup change contract).

PR (ready for review, +0/−102): #387

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This summary was automatically extracted from the AI working session output.

[konard]

🤖 Solution Draft Log

This log file contains the complete execution trace of the AI solution draft process.

💰 Cost: $2.412033

📊 Context and tokens usage:

• 89.4K / 1M (9%) input tokens, 22.6K / 128K (18%) output tokens

Total: (2.9K new + 137.7K cache writes + 1.9M cache reads) input tokens, 22.6K output tokens, $2.412033 cost

🤖 Models used:

• Tool: Anthropic Claude Code
• Requested: opus
• Model: Claude Opus 4.8 (claude-opus-4-8)

📎 Log file uploaded as Gist (1110KB)

• View complete solution draft log

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Now working session is ended, feel free to review and add any feedback on the solution draft.

[konard]

✅ Ready to merge

This pull request is now ready to be merged:

• All CI checks have passed
• No merge conflicts
• No pending changes

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