chore: bump version to 6.12.0

[tractorjuice]

Version bump for v6.12.0. Cut from main at 28610dc8.

Minor rather than patch because #818 raises the minimum Claude Code version users need installed, which changes an install requirement rather than only fixing behaviour.

What's in the release

Changed

• Claude Code floor raised v2.1.219 → v2.1.234 (chore: raise Claude Code minimum-version floor to v2.1.234 (#580) #818, feat: adopt Claude Code platform capabilities — rolling tracker (v2.1.236+) #580). Headline driver is v2.1.234 stopping MCP diagnostics printing resolved secrets: ArcKit ships two keyed MCP servers whose ${user_config.*} keys sit in request headers, and on a keyless session those connections fail by design, so ArcKit produced exactly those diagnostics as normal operation. Carries v2.1.221's WebSearch 400 at xhigh/max with thinking disabled, and the v2.1.222–v2.1.224 permission and sandbox bypass fixes.
• build.md session limits corrected, dispatch made explicit about background-by-default (fix: correct subagent-limit docs and dispatch assumptions for Claude Code v2.1.235 (#580) #817, feat: adopt Claude Code platform capabilities — rolling tracker (v2.1.236+) #580). v2.1.224 removed the 200-subagent-per-session spawn cap that fix: guard arckit-build waves against the subagent concurrency cap (#580) #675 documented, and the env var is now accepted-and-ignored. The WebSearch cap soft-degrades rather than denying, which the section had flattened.

Fixed

• READER-PATTERN.md stopped prescribing TodoWrite (fix: correct subagent-limit docs and dispatch assumptions for Claude Code v2.1.235 (#580) #817), removed on current models by v2.1.233. The 20 existing agent allowlists are deliberately unchanged; the entry is inert, not an error.

Plus everything merged after the v6.11.0 tag: the cloud-research reader/orchestrator/writer split (#812), gov-landscape and gov-code-search splits (#810, #811), the research split (#808), the restored agent tools allowlist (#807), SHA-pinned GitHub Actions (#813), "what ArcKit does not do" (#809), and the v6.11 release article (#819).

Release checks already run

• bump-version.sh 6.12.0, then converter.py, then sync-claude-plugin-layout.py (order is load-bearing: extensions are generated, so the converter must run after the bump and before the commit)
• Extension validation suite: 118 passed (Codex, Gemini, OpenCode, Copilot, Vibe, Paperclip, release process)
• Full Python suite: 1,545 passed, 225 skipped. Node plugin suite: 327 passed
• claude plugin tag <path> --dry-run against all 17 plugin manifests, with the count asserted and printed. That guard silently validated nothing from v6.0.0 to v6.7.4 because the glob matched zero manifests and the loop exited 0
• 84 files changed, all version-bearing. Staged with git add -u rather than -A

After merge

Tag v6.12.0 on the merged commit, tag-plugins.sh 6.12.0 for the native per-plugin tags, then push-extensions.sh for the standalone repos.

Refs #580

🤖 Generated with Claude Code

https://claude.ai/code/session_011ZrnfZmbdk33YD34j4Ys7H