feat: adopt Claude Code platform capabilities — rolling tracker (v2.1.236+)

[tractorjuice]

Summary

Clean follow-on from #522 (closed COMPLETED). The rolling Claude Code adoption tracker — each issue collects ~30 comments of changelog triage, then is superseded by a fresh issue carrying forward only what's still open.

Chain: #215 → #472 → #522 → this.

State carried over:

• Min-version floor: v2.1.234 (plugins/arckit-claude/hooks/version-check.mjs MIN_CLAUDE_CODE_VERSION) — raised from v2.1.219 in PR chore: raise Claude Code minimum-version floor to v2.1.234 (#580) #818 for the v2.1.234 MCP-diagnostics secret-exposure fix, v2.1.221's WebSearch 400 at xhigh/max, and the v2.1.222–v2.1.224 permission/sandbox bypass fixes. Prior floor context: v2.1.219 — raised from v2.1.200 in chore: raise Claude Code floor to v2.1.219 for Claude Opus 5 (#580) #676 / v6.6.0 for Claude Opus 5, carrying the v2.1.200 project-scoped-plugin/worktree and claude agents --plugin-dir fixes, the v2.1.198+ background-subagent reliability fixes, and the v2.1.172 WebFetch wildcard-subdomain fix. Bump actioned in PR chore: raise Claude Code minimum-version floor to v2.1.234 (#580) #818.
• Last changelog version triaged: v2.1.235. Resume triage from v2.1.236+. (v2.1.213 and v2.1.230 were never published.)

Changelog: https://github.com/anthropics/claude-code/releases

Carried-forward open candidates

Not committed work — platform capabilities flagged across triage that ArcKit has not adopted. Each needs a feasibility check before building.

• DirectoryAdded hook (v2.1.219) — fires after /add-dir or the SDK register_repo_root registers a new working directory mid-session. Natural companion to the shipped FileChanged handler (external-context-watch.mjs), which covers changes to projects/*/external/ evidence but not a whole evidence directory attached partway through a session.
• Subagent session ceilings — verify behaviour at the cap (v2.1.212, v2.1.217) — answered in fix: guard arckit-build waves against the subagent concurrency cap (#580) #675 (caps deny, they do not queue) and documented in build.md. Partly superseded by v2.1.224, which removed the 200-spawns-per-session cap entirely; 20 concurrent and the depth cap remain, and the WebSearch cap soft-degrades rather than denying. See the v2.1.221→235 triage — build.md needs a correction.
• SubagentStart / TaskCompleted hooks (present in the v2.1.235 binary, undocumented status unverified) — would let telemetry.mjs record subagent duration and outcome rather than only spawns, and TaskCompleted is a plausible wave-barrier mechanism under background-by-default dispatch. Check against published hooks docs first.
• Background-agent Notification hook telemetry/status (v2.1.198) — claude agents can emit agent_needs_input / agent_completed; ArcKit registers no Notification hook. Only worth doing once background-agent workflows need status capture.
• initialPrompt on agents (v2.1.83) — auto-submit first turn; runtime double-turn risk still unverified. (Confirmed no agent uses it today.)
• archive plugin source / air-gapped distribution (v2.1.224, supersedes the v2.1.129 .zip framing) — {"source": "archive", "url": "<https zip>", "sha256": "<64 hex>"} installs a plugin with no git and no npm, verifying the digest on every download. Gives air-gapped UK-Gov / MoD sites an internally-hosted, SHA-pinned install path for all 16 plugins. Needs a decision on which release step produces the zip + digest.
• disallowed-tools hardening (v2.1.152, v2.1.178, v2.1.186, v2.1.195) — candidate for read-only commands/skills (/arckit:search, /arckit:navigator, /arckit:health; reference skills). Later permission fixes make this more viable; still needs a scoped spike.
• SessionStart sessionTitle / reloadSkills (v2.1.152) — available but not yet used (could title sessions by active project).
• MessageDisplay redaction (v2.1.152) — speculative classification-aware screen redaction for OFFICIAL-SENSITIVE / SECRET; needs a concrete user request before building.
• sandbox.network.strictAllowlist / sandbox.filesystem.disabled (v2.1.219, v2.1.216) — egress-controlled and air-gapped deployments. Currently a docs candidate; becomes a build item only if we ship a recommended sandbox profile.

Documentation backlog

Open after #643 cleared the previous batch. Six items shipped in #674 (v2.1.201-220 batch).

• READER-PATTERN.md — correct the "subagents cannot spawn subagents" claim (nesting is depth 3 by default as of v2.1.219), and record why the orchestrators stay in the slash-command body regardless.
• CLAUDE.md — Opus 5 is the default Opus model (1M context); /fast covers Opus 5 and Opus 4.8 with Opus 4.7 dropped; add Opus 5 / Sonnet 5 to the effort matrix. provenance-model.mjs needs no matching change — say why.
• build.md — subagent session ceilings vs recipe sizes (44 / 38 / 38 / 11 targets) and the /clear budget reset. Gated on the cap-behaviour spike above.
• mcp-servers.md — MCP calls auto-background after 2 minutes (CLAUDE_CODE_MCP_AUTO_BACKGROUND_MS, v2.1.212), which interacts with the shipped MCP_TOOL_TIMEOUT=300000 guidance; per-server request_timeout_ms now honoured (v2.1.206); connect failures now show HTTP status and error text (v2.1.218).
• enterprise-scale.md / security-hooks.md — sandbox egress settings; one line noting plugin option values must be set at user scope, not project .claude/settings.json (v2.1.207).
• Research guides — the 200-per-session WebSearch cap and its override, for arckit-research and long autoresearch loops.
• Build/reader-pattern docs (PR fix: correct subagent-limit docs and dispatch assumptions for Claude Code v2.1.235 (#580) #817) — background-by-default verified and documented in both build.md and READER-PATTERN.md. v2.1.232 made non-teammate spawns background-by-default in interactive sessions, and the Agent tool returns async_launched + an agentId rather than a report. arckit-build's wave barrier and every reader→writer handoff assume synchronous returns.
• build.md correction (v2.1.224) (PR fix: correct subagent-limit docs and dispatch assumptions for Claude Code v2.1.235 (#580) #817) — delete the per-session spawn-cap row and its denial string, correct the WebSearch row to soft-degrade, note that CLAUDE_CODE_MAX_SUBAGENTS_PER_SESSION is now accepted and ignored.
• READER-PATTERN.md (v2.1.233) (PR fix: correct subagent-limit docs and dispatch assumptions for Claude Code v2.1.235 (#580) #817 — prescriptive copy fixed; the 20 agent allowlists deliberately left as-is, entry is inert) — TodoWrite no longer exists on Opus 4.8 / Sonnet 5 / Fable 5 / Opus 5 and newer. Line 128 prescribes it for every new reader.
• RELEASING.md (v2.1.233) — claude plugin validate now reports SKILL.md files whose frontmatter fails to parse; add to the pre-release validation step.
• enterprise-scale.md (v2.1.223) — owner/* wildcards in strictKnownMarketplaces / blockedMarketplaces.
• Research guides (v2.1.233) — CLAUDE_CODE_WEBFETCH_CACHE_TTL_MS for the 15-minute WebFetch session URL cache, for long autoresearch loops.

Ongoing

• Triage new Claude Code releases from v2.1.236 onward — one comment per batch, continuing the established High-Value / Critical Fixes / Documentation / Min-Version Floor format, verifying claims against the repo and primary docs.

Resolved / audit notes

• Subagent-nesting re-homing candidate — closed "won't do" (v2.1.201→220 triage). The default flipped 5 (v2.1.172) → 1 (v2.1.217) → 3 (v2.1.219) and is user-overridable via CLAUDE_CODE_MAX_SUBAGENT_SPAWN_DEPTH. Moving the datascout / grants / gov-reuse orchestrators into agents/ would make them fail outright — not degrade — for any user who sets depth back to 1. Current placement is robust in both directions; only the stale READER-PATTERN.md note needs fixing.
• ${user_config.*} shell-injection restriction (v2.1.207) — ArcKit verified compliant on every path: exec-form hooks, CLAUDE_PLUGIN_OPTION_* in notify-stale-artifacts.mjs, ${CLAUDE_PLUGIN_ROOT}-only monitor command, and direct headers (not headersHelper) MCP substitution. Confirmed empirically on a v2.1.220 session.
• Hook if: single-segment glob change (v2.1.214) — checked and clear: all 8 if: conditions are leading-slash anchored, none is a bare dir/**.
• Opus 5 effort matrix — provenance-model.mjs needs no change; MODEL_EFFORTS lists only partial-support models and treats absent models as full-support, which is the provenance effort matrix: EFFORT_RANK inverts max/xhigh; single cap can't model Opus 4.6 support gap #669 design absorbing a new top-tier model with no edit.
• Documentation batch shipped in docs: update Claude Code platform guidance #643: managed model governance + enforceAvailableModels, OTEL assistant-response caveat, MCP auth / headersHelper refresh behaviour, v2.1.200+ plugin branch-testing guidance, --safe-mode troubleshooting + disableBundledSkills caveat, root-level SKILL.md layout note, refreshed model examples.
• Fallback-model docs + managed-settings v2.1.166 caveat shipped in docs: note Claude Code v2.1.166 fallbackModel + managed-settings hardening #587.
• WebFetch wildcard-domain floor shipped in chore(version): bump Claude Code min-version floor to v2.1.172 #593 / v5.13.1, carried inside the newer v2.1.200 floor.
• Hook if: path-rule floor candidate (v2.1.176) covered by the v2.1.200 floor bump.
• Root-level SKILL.md (v2.1.142) — N/A for ArcKit's layout; documented in docs: update Claude Code platform guidance #643, no longer a carried candidate.
• Shared MCP headersHelper (v2.1.85, v2.1.193) — documented in docs: update Claude Code platform guidance #643; ArcKit uses direct headers substitution for its two keyed servers, so consolidation has no remaining driver. Closed.
• Stop-hook end-of-turn nudge (feat(hooks): end-of-turn traceability nudge from the Stop hook (#522 item 70) #578, item 70); per-agent telemetry attribution (feat(telemetry): attribute tool/MCP activity by agent (#522 items 33/52/63) #579, items 33/52/63 — re-scoped: parent_agent_id not in hook input); minimumVersion floor guidance (feat(version-check): recommend and dogfood minimumVersion floor pin #575, item 92).
• Doc adoption for v2.1.161–163 (docs: adopt Claude Code v2.1.161–163 capability notes (#522) #576): enterprise-scale Fleet & Version Governance, MCP timeout-floor + claude mcp redaction, --fallback-model, WebFetch domain-scoping, \$ escape, /plugin list, pluginSuggestionMarketplaces, CLAUDE.md frontmatter/hook mentions.
• effort: max audit (docs(claude): correct effort-tier per-model accuracy (#522) #577 — verified valid, no change); MCP_TOOL_TIMEOUT docs; terminalSequence (adopted in notify-stale-artifacts.mjs); community-overlay arckit dependency (verified declared on all 9).

Reference

• Previous tracker: feat: adopt Claude Code v2.1.143–v2.1.163 platform capabilities #522 (closed COMPLETED 2026-06-05)
• Earlier: feat: Claude Code platform adoption — outstanding items from #215 #472, feat: adopt Claude Code v2.1.83–2.1.128 plugin capabilities #215

[tractorjuice]

Triage: Claude Code v2.1.164 → v2.1.168

Resuming from v2.1.163. v2.1.164 was not published; v2.1.165 / 2.1.167 / 2.1.168 are bug-fix/reliability rollups with no itemised changes. The only substantive release in this batch is v2.1.166.

Verified against the repo working tree and the changelog. Net result: no code change, no floor bump, no hard gate — one doc-upgrade candidate flagged below.

---

🟢 High-Value (v2.1.166)

• fallbackModel setting (up to 3 models) + --fallback-model now applies to interactive sessions + retry-once-on-fallback. This is a real upgrade over what ArcKit already documents. docs/guides/autoresearch.md:243 currently describes a single --fallback-model for unattended overnight loops only (v2.1.152+). The 2.1.166 changes: (a) a settings-based fallbackModel taking up to three models tried in order; (b) --fallback-model now also covers interactive sessions, so a long interactive /arckit:research survives an Opus capacity blip too; (c) Claude Code now retries a turn once on the fallback model when the API returns an unexpected non-retryable error (auth/rate-limit/request-size/transport still surface immediately). → Doc candidate (checkbox below), no code.

• Glob patterns in deny-rule tool-name position ("*" denies all tools); allow rules reject non-MCP globs; unknown tool names in deny rules now warn at startup. This is the settings.json deny-rule mechanism, adjacent to but distinct from the carried-forward disallowed-tools: frontmatter candidate (which is per-command/skill, not settings-wide). Relevant if we ever ship a fleet-wide read-only posture via managed settings — the startup-warn-on-unknown-tool-name safety net removes a class of silent-typo footgun. No adoption needed now; noted for the disallowed-tools hardening line.

• Cross-session messaging hardened — messages relayed via SendMessage from other sessions no longer carry user authority; receivers refuse relayed permission requests and auto mode blocks them. Verified N/A to ArcKit (grep SendMessage plugins/arckit-claude/ → none). Security-positive for any user running ArcKit alongside channel/multi-session setups.

🔧 Critical Fixes (v2.1.166) — relevant to ArcKit guidance

• Managed settings with an invalid entry no longer silently disable enforcement of the remaining valid policies. This directly strengthens the Fleet & Version Governance guidance in docs/guides/enterprise-scale.md:218-233 (shipped in docs: adopt Claude Code v2.1.161–163 capability notes (#522) #576): previously a single typo in an org's managed-settings file could silently switch off the requiredMinimumVersion: "2.1.156" floor we recommend, leaving the fleet unprotected with no signal. Fixed in 2.1.166 — valid policies keep enforcing.
• allowedMcpServers / deniedMcpServers managed-settings predicates now match when they use ${VAR} references. Relevant to fleet MCP governance for ArcKit's 6 bundled servers.
• Quality-of-life: claude update now announces the target version before downloading; recurring "image could not be processed" + token-waste fix; several remote/background-agent and IDE-terminal fixes. None touch ArcKit behaviour.

📄 Documentation

• Upgrade the fallback-model note in docs/guides/autoresearch.md (currently single-model, unattended-only, v2.1.152) to cover the 2.1.166 reality: settings-based fallbackModel with up to three models, applies to interactive sessions, and the automatic retry-once-on-fallback. Optionally add a one-line caveat to docs/guides/enterprise-scale.md that a malformed managed-settings file no longer silently disables the version floor (hardened in v2.1.166). Low effort; bundle into the next docs sweep — not worth a standalone release.

📌 Min-Version Floor

No change — floor holds at v2.1.156. Nothing in v2.1.164–v2.1.168 is a must-adopt capability that ArcKit relies on. Note the $TMPDIR override regression (2.1.154→.163) that was flagged as a prior floor consideration was fixed in v2.1.163, so it no longer spans the supported range.

---

Last changelog version triaged: v2.1.168. Resume next batch from v2.1.169+.

[tractorjuice]

✅ Documentation candidate shipped — the fallback-model upgrade (autoresearch.md) and the managed-settings v2.1.166+ enforcement caveat (enterprise-scale.md) landed in #587 (squash-merged to main as 7b8522fe, lint clean). No code change, floor holds at v2.1.156. The v2.1.164–v2.1.168 batch is now fully closed out.

[tractorjuice]

Triage: Claude Code v2.1.169

Resuming from v2.1.168. v2.1.169 is the only new release since the last batch — and the first itemised one since v2.1.166 (2.1.167/.168 were bug-fix rollups, already noted above).

Verified against the working tree and the changelog. Net result: no code change, no floor bump, no hard gate — two small doc candidates flagged below.

---

🟢 High-Value (v2.1.169)

• --safe-mode flag + CLAUDE_CODE_SAFE_MODE env — disables customizations (plugins, hooks, skills) for troubleshooting. This is a genuinely useful support primitive for ArcKit: when a user reports odd behaviour, "reproduce with claude --safe-mode to confirm it isn't an ArcKit hook/skill" is a clean first triage step that isolates the 16 registered hooks + 5 skills + monitor in one move. There is no troubleshooting guide in docs/guides/ today (grep -rln "safe-mode\|troubleshoot" docs/guides/ → none), so this is net-new doc surface, not an edit. → Doc candidate (checkbox below).

• disableBundledSkills setting + CLAUDE_CODE_DISABLE_BUNDLED_SKILLS env. Verified N/A to ArcKit's behaviour — this disables Claude Code's own bundled skills, not plugin-provided skills. ArcKit's 5 skills live under plugins/arckit-claude/skills/ (plugin skills), so they keep working with this set. Worth a one-line clarification in adoption docs to pre-empt the user assumption that this flag turns ArcKit off (it doesn't; --safe-mode is the flag that does).

• /cd command — relocate a session to a new working directory while preserving the prompt cache. Minor, but note for support: ArcKit's bash helpers resolve the repo root by walking up for a numbered projects/NNN-* entry (findRepoRoot, hardened in fix(hooks): gate findRepoRoot on a numbered projects/ entry + Windows path fix #572). A mid-session /cd into a different repo re-points that resolution, which is the correct behaviour but worth knowing when diagnosing "wrong project picked up" reports. No code action.

🔧 Critical Fixes (v2.1.169) — relevant to ArcKit guidance

• Enterprise MCP policies now enforce on reconnect, IDE configs, and --mcp-config servers (previously only at initial startup). This directly strengthens the Fleet & Version Governance MCP story in docs/guides/enterprise-scale.md — the same thread as the v2.1.166 allowedMcpServers/deniedMcpServers ${VAR} fix (docs: note Claude Code v2.1.166 fallbackModel + managed-settings hardening #587). ArcKit ships 6 type: http MCP servers, all alwaysLoad; an org denied-listing one of them now stays denied across a reconnect, closing a bypass window. Upstream fix, no ArcKit code — reinforces existing guidance.
• TaskCreate reliability improved (automatic input repair + clearer validation errors). Relevant — ArcKit leans hard on Task-tool dispatch (reader/writer subagent trios, arckit-build parallel waves) and registers a TaskCreated telemetry hook (hooks.json:299 → telemetry.mjs:76). More reliable spawns = fewer dropped agents mid-orchestration and cleaner per-agent telemetry (the feat(telemetry): attribute tool/MCP activity by agent (#522 items 33/52/63) #579 work). Upstream win, no action.
• Untrusted project settings can no longer configure OTEL certificate paths without confirmation. Security-positive and adjacent to the OTEL guidance shipped in docs: adopt Claude Code v2.1.161–163 capability notes (#522) #576 (enterprise-scale.md:245, OTEL_RESOURCE_ATTRIBUTES). No ArcKit change — ArcKit's own telemetry is local docs/telemetry.json, not an OTEL exporter — but good to know for users who enable Claude Code's OTEL export in a governed fleet.
• Plugin .in_use PID lock files no longer accumulate without cleanup. Housekeeping fix that affected every installed plugin including ArcKit; resolved upstream, no action.
• "CLAUDE.md is too long" warning threshold now scales with the model's context window. ArcKit's CLAUDE.md is dense (262 lines, project-instruction heavy); a fixed threshold previously risked a spurious warning on large-context models. Minor positive, no action.
• Also: claude -p no longer hangs on Windows during slash-command scanning (relevant given ArcKit's 58 core commands), background agents now honour project-level env settings, and assorted Windows/WSL/remote fixes. None touch ArcKit behaviour.

📄 Documentation

• Add a short Troubleshooting note (new docs/guides/ content or a section in an existing guide) covering: (a) claude --safe-mode / CLAUDE_CODE_SAFE_MODE=1 to isolate whether an issue is ArcKit's hooks/skills; (b) a one-liner clarifying that disableBundledSkills does not disable ArcKit's plugin skills (use --safe-mode or /plugin for that). Low effort; bundle into the next docs sweep — not worth a standalone release.

📌 Min-Version Floor

No change — floor holds at v2.1.156. Nothing in v2.1.169 is a must-adopt capability ArcKit depends on. The enterprise-MCP and TaskCreate fixes are upstream reliability/security improvements that benefit ArcKit transparently without requiring a floor bump.

---

Last changelog version triaged: v2.1.169. Resume next batch from v2.1.170+.

[tractorjuice]

Triage: Claude Code v2.1.170 → v2.1.173

Resuming from v2.1.169. Three itemised releases in this batch — v2.1.170, v2.1.172, v2.1.173 (v2.1.171 was not published). v2.1.172 is the substantive one.

Verified against the working tree and the changelog. Net result: no code change and no floor bump this batch — but one genuine architectural opportunity (subagent nesting) and one doc-caveat where an existing ArcKit recommendation was silently broken before v2.1.172.

---

🟢 High-Value

• Sub-agents can now spawn their own sub-agents — up to 5 levels deep (v2.1.172). This directly contradicts the architectural premise of the reader/writer pattern. arckit-claude/agents/READER-PATTERN.md:79 states, citing the official docs, that "Subagents cannot spawn other subagents" — and that is the entire reason the orchestrator role for datascout / grants / gov-reuse lives in the slash-command body rather than in an agent file (only the main thread could call Agent to dispatch reader + writer). If subagents can now nest, the orchestrator could move into a proper agents/arckit-{name}.md file, simplifying the three-tier split and isolating orchestration context off the main thread. → Investigation candidate (not committed): confirm the nesting applies to the plugin Agent runtime (not just the Managed Agents API the doc note distinguishes), then decide whether to (a) re-home the three orchestrators as agents and (b) correct the now-stale claim in READER-PATTERN.md. Material enough to warrant a feasibility spike before any v6 restructure. Caution: a depth-5 ceiling + ArcKit's existing trio depth means we'd want guardrails so a future overlay can't accidentally fan out beyond the cap.

• Introducing Claude Fable 5 — Mythos-class, generally available (v2.1.170). New top-tier model (claude-fable-5; /fast and effort: tiers unaffected by this entry). ArcKit pins no model in command/agent frontmatter for the heavy commands — they inherit the session model — so Fable 5 is picked up transparently with no code change. grep -rln "Fable" docs/guides/ plugins/arckit-claude/ → none, so the model-choice guidance in docs/guides/ doesn't yet mention it. Low-value doc note only — the existing Opus-4.8-centric guidance still holds; a one-liner that Fable 5 is now an option can ride the next docs sweep. No floor implication (it's available from 2.1.170, below would simply not see it).

🔧 Critical Fixes — relevant to ArcKit guidance

• WebFetch(domain:*.example.com) wildcard rules never matched subdomains — fixed in v2.1.172. This is a real correctness issue for shipped ArcKit guidance: docs/guides/security-hooks.md:142-144 recommends exactly this shape for regulated/OFFICIAL-SENSITIVE deployments —

  "WebFetch(domain:*.gov.uk)",
  "WebFetch(domain:*.service.gov.uk)",
  

  Before v2.1.172 those wildcard rules silently never matched (www.gov.uk, docs.aws.amazon.com via *.amazon.com, etc.), so a deny-then-wildcard-allow policy would have blocked all WebFetch traffic for the research agents rather than scoping it. → Doc-caveat candidate: add a note to security-hooks.md that wildcard domain:*.x rules require v2.1.172+ to match subdomains (and that the v2.1.162 precedence fix already documented there is necessary but not sufficient below 2.1.172). Optional exact-host fallback for pre-2.1.172 fleets. Low effort; bundle into the next docs sweep.

• availableModels / availableModels restrictions now apply to subagent model overrides (v2.1.172). Strengthens the Fleet & Version Governance story (docs/guides/enterprise-scale.md): a managed availableModels allowlist now also constrains what ArcKit's 16 agents can override to, closing a bypass where a subagent could select a disallowed model. Upstream fix, no ArcKit code — reinforces existing guidance.

• Workflow validation no longer rejects scripts mentioning Date.now() / Math.random() (v2.1.172). Relevant only if a user authors Workflow-tool scripts around ArcKit; ArcKit's own arckit-build skill uses direct Agent dispatch, not the Workflow tool, so N/A to bundled behaviour. Noted for awareness.

• Added model attribute to claude_code.lines_of_code.count OTEL metric (v2.1.172). Adjacent to the OTEL guidance in enterprise-scale.md. ArcKit's own telemetry is local (docs/telemetry.json), not an OTEL exporter, so N/A to ArcKit — relevant only to users who enable Claude Code's OTEL export in a governed fleet.

• Marketplace /plugin now has a search bar + cursor-retention fixes (v2.1.172). Pure QoL, but a genuine positive given the marketplace now lists 13 ArcKit plugins (core + 12 overlays) — easier discovery. No action.

• Bedrock reads AWS region from ~/.aws when AWS_REGION unset (v2.1.172); Bedrock /model picker no longer offers unavailable models. Minor fleet/Bedrock quality wins for users running ArcKit on Bedrock. No ArcKit change.

• Also in v2.1.172: numerous background/nested-subagent lifecycle fixes (stuck "active" subagents, background agents reading another directory's project settings, doubled [1M][1m] suffix, opusplan 1M context). All upstream reliability — ArcKit leans on Task-tool dispatch for the reader/writer trios and arckit-build waves, so the "subagent stuck active after nested agent stopped" and "background agent reading wrong project settings" fixes benefit ArcKit orchestration transparently. No action.

🟢 Housekeeping (v2.1.173)

• Fable 5 model names with [1m] suffix now normalised (Fable 5 ships 1M context by default); spurious Windows "sandbox dependencies missing" startup warning fixed. Model-ID hygiene + Windows polish — no ArcKit impact.

📄 Documentation (carry into next sweep — none worth a standalone release)

• security-hooks.md: note that WebFetch(domain:*.x) wildcard subdomain matching needs v2.1.172+ (the recommended *.gov.uk / *.service.gov.uk rules were silently inert below it).
• Model guidance: one-liner that Claude Fable 5 (claude-fable-5) is now a generally-available top-tier option (v2.1.170+), inherited transparently since ArcKit pins no model on heavy commands.

🔬 Investigation (pre-v6 spike, not committed)

• Subagent nesting (v2.1.172): verify depth-5 nesting applies to the plugin Agent runtime; if so, evaluate re-homing the datascout / grants / gov-reuse orchestrators from slash-command bodies into agents/ files and correct the stale "subagents cannot spawn subagents" note in READER-PATTERN.md:79.

📌 Min-Version Floor

No change — floor holds at v2.1.156. Nothing in v2.1.170–v2.1.173 is a must-adopt capability ArcKit depends on. The WebFetch wildcard fix matters only for the optional domain-scoping hardening (handle with a version caveat in the guide, not a fleet-wide floor bump); subagent nesting is an opportunity, not a dependency.

---

Last changelog version triaged: v2.1.173. Resume next batch from v2.1.174+.

[tractorjuice]

Floor bumped to v2.1.172 — shipped in v5.13.1

Acting on the v2.1.170→173 triage above: the WebFetch wildcard-domain fix (v2.1.172) makes ArcKit's shipped WebFetch(domain:*.gov.uk) security-hooks guidance actually hold (it silently never matched subdomains below v2.1.172). Rather than add a per-guide version caveat, I raised the floor.

• PR chore(version): bump Claude Code min-version floor to v2.1.172 #593 (squash 8728c366) — MIN_CLAUDE_CODE_VERSION v2.1.156 → v2.1.172 + every floor reference (CLAUDE.md, README, enterprise-scale.md, hooks/README.md, repo + test-repo .claude/settings.json).
• Released as v5.13.1 (tag v5.13.1, release.yml SUCCESS, GitHub Release live, 13 native plugin tags + all 5 ext repos pushed).

Floor also covers the Claude Fable 5 runtime (GA in v2.1.170). The carried-forward subagent-nesting investigation (v2.1.172) remains open — separate, pre-v6 spike.

[tractorjuice]

Triage: Claude Code v2.1.174 -> v2.1.196

Resuming from v2.1.173. Reviewed the live Claude Code changelog on 2026-06-30.

Published headings in this batch: v2.1.174, v2.1.175, v2.1.176, v2.1.178, v2.1.179, v2.1.181, v2.1.183, v2.1.185, v2.1.186, v2.1.187, v2.1.190, v2.1.191, v2.1.193, v2.1.195, v2.1.196.

No published headings found for v2.1.177, v2.1.180, v2.1.182, v2.1.184, v2.1.188, v2.1.189, v2.1.192, or v2.1.194.

Net result: no immediate ArcKit code change and no floor bump in this comment. v2.1.176 is the one plausible floor candidate from this batch because ArcKit uses hook if: path scoping in hooks.json, and that release fixed documented Read/Edit/Write path forms. Keep v2.1.172 until we prove an ArcKit hook misses or misfires on v2.1.172-v2.1.175.

High-value / candidate follow-ups

• Hook if: path matching (v2.1.176): ArcKit has project and Wardley path-scoped hooks such as Write(/projects/**), Write(/projects/**/wardley-maps/**), and Edit(/projects/**). Add a focused verification before the next release; bump the minimum to v2.1.176 only if the supported v2.1.172-v2.1.175 range is affected in practice.
• Agent/tool permission hardening (v2.1.178, v2.1.186, v2.1.195): Tool(param:value) rules, subagent classifier checks, fixed MCP server disallow specs in subagent disallowedTools, named-Agent allow/deny enforcement, and hyphenated matcher exactness make the carried-forward disallowed-tools hardening more viable. Candidate: evaluate read-only commands and reader agents with Agent and MCP restrictions.
• Managed model governance (v2.1.175, v2.1.176, v2.1.187, v2.1.196): enforceAvailableModels, stronger alias/default enforcement, org-configured model restrictions, and org default models are relevant to enterprise deployments. Candidate: docs update; no ArcKit code dependency.
• MCP/plugin governance (v2.1.186, v2.1.191, v2.1.193, v2.1.195, v2.1.196): CLI MCP login/logout, MCP retry improvements, headersHelper reconnect on 401/403, external plugin consent, plugin auto-renames, local marketplace dependency pins, and local-source plugin validation all help ArcKit operators. Candidate: update MCP/plugin developer docs.
• OTEL/privacy docs (v2.1.193): assistant-response telemetry can follow prompt logging unless explicitly disabled. Candidate: add a regulated-fleet caveat to enterprise docs.
• Sandbox/auto-mode safety (v2.1.183, v2.1.187): destructive git command blocks and sandbox.credentials are security-positive but do not require ArcKit changes.
• Background/Remote/session reliability (v2.1.174 -> v2.1.196): multiple background job, subagent depth, worktree, Remote Control, and stream-watchdog fixes benefit ArcKit orchestration transparently.

No action

• Hook matcher comma fix (v2.1.191): ArcKit uses pipe alternation such as Read|Bash and Edit|Write, plus mcp__.*, not comma-separated matchers.
• Hyphenated hook matcher exact-match (v2.1.195): ArcKit's native matcher is mcp__.*; the MCP allowlist hook performs JavaScript prefix checks, so there is no matcher migration.
• Agent teams removal (v2.1.178): ArcKit does not use experimental TeamCreate/TeamDelete.
• initialPrompt, FileChanged / CwdChanged, and MessageDisplay redaction remain unadopted; this batch does not add enough evidence to move them ahead of the existing backlog.
• Root-level SKILL.md remains docs-only / not applicable to ArcKit's current layout.

Documentation backlog

• enterprise-scale.md: managed model governance (enforceAvailableModels, org defaults, org restrictions) and OTEL assistant-response logging caveat.
• MCP/server docs: claude mcp login/logout, MCP retry/headless OAuth improvements, and headersHelper 401/403 refresh behavior.
• Hook docs or release notes: v2.1.176 hook if: path-matching verification outcome.
• Plugin developer/release notes: plugin validate local-source fix and dependency pins honored for local folder/git marketplaces.

Investigation

• Test ArcKit hook if: path rules against v2.1.172-v2.1.175 vs v2.1.176+; decide whether to raise the floor to v2.1.176.
• Revisit carried-forward disallowed-tools hardening with the v2.1.178/v2.1.186 permission fixes in mind.
• Subagent nesting remains carried forward from v2.1.172; this batch adds reliability/depth fixes but does not close the architecture spike.

Min-Version Floor

No change yet: floor remains v2.1.172. v2.1.176 is the only candidate from this batch, pending verification that ArcKit hook if: path scoping is affected in practice.

Last changelog version triaged: v2.1.196. Resume next batch from v2.1.197+.

[tractorjuice]

Triage: Claude Code v2.1.197 -> v2.1.200

Resuming from v2.1.196. Reviewed the live Claude Code GitHub Releases page on 2026-07-03. Latest published release at review time: v2.1.200 (published 2026-07-03 16:52 UTC).

Published headings in this batch: v2.1.197, v2.1.198, v2.1.199, v2.1.200.

Net result: no immediate ArcKit code change and no minimum-version floor bump. This batch strengthens two existing tracker themes: subagent/background-runtime verification, and docs around model defaults plus plugin/worktree testing.

High-value / candidate follow-ups

• Background-by-default subagents (v2.1.198) plus subagent partial-output/error propagation fixes (v2.1.199/v2.1.200): ArcKit uses Agent heavily. /arckit:build dispatches parallel general-purpose subagents in waves; the tenders/competitors/datascout/grants/gov-reuse reader-writer flows expect explicit handoff results; hooks.json records TaskCreated telemetry. Add a focused runtime check on v2.1.198+ to confirm background-by-default agents still produce deterministic handoff summaries before validation/commit and that session telemetry closes after background work, not before it.
• Background-agent Notification events (v2.1.198): claude agents now fires agent_needs_input / agent_completed. ArcKit registers no Notification hook today; session-learner.mjs handles Stop / StopFailure, and telemetry handles TaskCreated / PostToolUse. Candidate only after background-agent workflows matter: likely a telemetry/status hook, not a core behavior dependency.
• Claude Sonnet 5 default (v2.1.197): ArcKit does not pin heavy command models, so it inherits the new default transparently. Docs/model guidance should mention Sonnet 5 as the current default/top-tier option and refresh stale example model IDs where they still name claude-sonnet-4-5-20250929.
• Git worktree/project-scoped plugin loading fix (v2.1.200): directly relevant to ArcKit branch/plugin testing. docs/guides/testing-plugin-branches.md documents project-scoped marketplace settings and claude --plugin-dir; add a caveat that worktree/project-scoped plugin tests should use v2.1.200+ when relying on project settings rather than only --plugin-dir.
• AskUserQuestion no longer auto-continues by default (v2.1.200): ArcKit has interactive commands/skills that call AskUserQuestion, but they wait for explicit answers and do not rely on timeout-driven continuation. No code action; note only if future docs describe unattended interactive flows.

Critical fixes / upstream wins relevant to ArcKit

• v2.1.198: subagents inherit extended thinking; background jobs/tasks get multiple stuck-state fixes; .claude/rules/ conditional rules work through symlinked paths; plan-mode read-only tool auto-allow is fixed.
• v2.1.199: subagents cut off by rate limits/server errors now return partial work or report the error to the parent instead of silently succeeding; SessionStart, Setup, and SubagentStart hooks now show stderr when they exit 2; transient 429 retry behavior improves.
• v2.1.200: project-scoped plugins load correctly from git worktrees; claude agents --plugin-dir <dir> shows plugin agents/skills even when the flag is placed after agents; startup crash fixed for malformed .claude.json disabledMcpServers / enabledMcpServers; more background-agent resume/daemon fixes.

No action

• Minimum-version floor: no change. Floor remains v2.1.172. v2.1.176 remains the earlier plausible floor candidate pending hook if: path-scope verification; this batch does not add a core runtime dependency that requires v2.1.197+.
• /dataviz skill (v2.1.198): built-in Claude Code skill; no ArcKit collision or adoption requirement.
• /agents wizard removal (v2.1.198): ArcKit docs do not point users at that wizard.
• Permission mode label change from default to manual (v2.1.200): no ArcKit config migration found.
• disabledMcpServers / enabledMcpServers malformed-value crash fix (v2.1.200): upstream robustness only; not an ArcKit config pattern.

Documentation backlog

• docs/guides/testing-plugin-branches.md: mention v2.1.200+ for project-scoped plugin loading from git worktrees and the claude agents --plugin-dir fix.
• Model guidance: add Claude Sonnet 5 as the current Claude Code default/top-tier option; keep the Fable 5 note only where still useful.
• docs/guides/build.md / reader-pattern docs: record background-by-default subagent verification once tested.

Investigation

• Test /arckit:build wave dispatch under v2.1.198+ background-by-default subagents.
• Test one reader-writer flow (/arckit:tenders or /arckit:competitors) under v2.1.198+ and confirm handoff validation still gates the writer.
• Decide whether a Notification hook should record background-agent completion / needs-input status in telemetry.
• Carry forward the existing v2.1.176 hook if: path-rule verification and the v2.1.172 subagent-nesting architecture spike.

Min-Version Floor

No change: floor remains v2.1.172. v2.1.200 may become a recommended testing floor for worktree/project-scoped plugin development, but not a required ArcKit runtime floor.

Last changelog version triaged: v2.1.200. Resume next batch from v2.1.201+.

[tractorjuice]

Floor bumped to v2.1.200

Follow-up to the v2.1.197 -> v2.1.200 triage above: the minimum Claude Code floor is now being raised from v2.1.172 to v2.1.200.

Rationale:

• v2.1.200 fixes project-scoped plugin loading from git worktrees and claude agents --plugin-dir <dir> visibility for plugin agents/skills, both directly relevant to ArcKit branch/test-repo workflows.
• v2.1.198-v2.1.199 carry the background-subagent reliability, parent error-propagation, and hook stderr-visibility fixes that matter to /arckit:build, reader/writer handoffs, and hook diagnosis.
• v2.1.197 carries the Claude Sonnet 5 default runtime and native 1M context.
• The older v2.1.172 WebFetch wildcard-domain fix remains part of the floor rationale.

Repo changes made locally:

• plugins/arckit-claude/hooks/version-check.mjs: MIN_CLAUDE_CODE_VERSION = '2.1.200' plus warning bullets.
• .claude/settings.json and .claude/commands/create-test-repo.md: minimumVersion bumped to 2.1.200.
• docs/guides/enterprise-scale.md: managed-settings requiredMinimumVersion example bumped to 2.1.200.
• Hook docs/comments and current install/guide docs updated to avoid stale v2.1.121/v2.1.172 floor text.

The earlier v2.1.176 hook if: path-rule candidate is now covered by the v2.1.200 floor bump; no separate v2.1.176 floor decision remains open.