build

name	build
preamble-tier	1
version	0.1.0
description	Canonical Nexus build command. Executes the bounded governed implementation contract and writes repo-visible build request, result, and stage status artifacts. Use when the user says "implement task X", "build the feature", "execute the sprint contract", or otherwise asks to turn a planned task into shipped code with verification. (nexus)
allowed-tools	["Bash","Read","AskUserQuestion"]

Preamble (run first)

_UPD=$(~/.claude/skills/nexus/bin/nexus-update-check 2>/dev/null || .claude/skills/nexus/bin/nexus-update-check 2>/dev/null || true)
[ -n "$_UPD" ] && echo "$_UPD" || true
mkdir -p ~/.nexus/sessions
touch ~/.nexus/sessions/"$PPID"
_SESSIONS=$(find ~/.nexus/sessions -mmin -120 -type f 2>/dev/null | wc -l | tr -d ' ')
find ~/.nexus/sessions -mmin +120 -type f -exec rm {} + 2>/dev/null || true
_CONTRIB=$(~/.claude/skills/nexus/bin/nexus-config get nexus_contributor 2>/dev/null || true)
_PROACTIVE=$(~/.claude/skills/nexus/bin/nexus-config get proactive 2>/dev/null || echo "true")
_PROACTIVE_PROMPTED=$([ -f ~/.nexus/.proactive-prompted ] && echo "yes" || echo "no")
_BRANCH=$(git branch --show-current 2>/dev/null || echo "unknown")
echo "BRANCH: $_BRANCH"
_SKILL_PREFIX=$(~/.claude/skills/nexus/bin/nexus-config get skill_prefix 2>/dev/null || echo "false")
echo "PROACTIVE: $_PROACTIVE"
echo "PROACTIVE_PROMPTED: $_PROACTIVE_PROMPTED"
echo "SKILL_PREFIX: $_SKILL_PREFIX"
_MODE_CONFIGURED=$(~/.claude/skills/nexus/bin/nexus-config get execution_mode 2>/dev/null || true)
_PRIMARY_PROVIDER_CONFIG=$(~/.claude/skills/nexus/bin/nexus-config get primary_provider 2>/dev/null || true)
_TOPOLOGY_CONFIG=$(~/.claude/skills/nexus/bin/nexus-config get provider_topology 2>/dev/null || true)
if command -v ask >/dev/null 2>&1; then
  _CCB_AVAILABLE="yes"
else
  _CCB_AVAILABLE="no"
fi
if [ -n "$_MODE_CONFIGURED" ]; then
  _EXECUTION_MODE="$_MODE_CONFIGURED"
  _EXECUTION_MODE_CONFIGURED="yes"
else
  _EXECUTION_MODE_CONFIGURED="no"
  if [ "$_CCB_AVAILABLE" = "yes" ]; then
    _EXECUTION_MODE="governed_ccb"
  else
    _EXECUTION_MODE="local_provider"
  fi
fi
if [ "$_EXECUTION_MODE" = "governed_ccb" ]; then
  _PRIMARY_PROVIDER="codex"
  _PROVIDER_TOPOLOGY="multi_session"
else
  if [ -n "$_PRIMARY_PROVIDER_CONFIG" ]; then
    _PRIMARY_PROVIDER="$_PRIMARY_PROVIDER_CONFIG"
  elif command -v claude >/dev/null 2>&1; then
    _PRIMARY_PROVIDER="claude"
  elif command -v codex >/dev/null 2>&1; then
    _PRIMARY_PROVIDER="codex"
  elif command -v gemini >/dev/null 2>&1; then
    _PRIMARY_PROVIDER="gemini"
  else
    _PRIMARY_PROVIDER="claude"
  fi
  if [ -n "$_TOPOLOGY_CONFIG" ]; then
    _PROVIDER_TOPOLOGY="$_TOPOLOGY_CONFIG"
  else
    _PROVIDER_TOPOLOGY="single_agent"
  fi
fi
_EFFECTIVE_EXECUTION=$(~/.claude/skills/nexus/bin/nexus-config effective-execution 2>/dev/null || true)
if [ -n "$_EFFECTIVE_EXECUTION" ]; then
  _EXECUTION_MODE=$(printf '%s
' "$_EFFECTIVE_EXECUTION" | awk -F': ' '/^execution_mode:/{print $2; exit}')
  _EXECUTION_MODE_CONFIGURED=$(printf '%s
' "$_EFFECTIVE_EXECUTION" | awk -F': ' '/^execution_mode_configured:/{print $2; exit}')
  _PRIMARY_PROVIDER=$(printf '%s
' "$_EFFECTIVE_EXECUTION" | awk -F': ' '/^effective_primary_provider:/{print $2; exit}')
  _PROVIDER_TOPOLOGY=$(printf '%s
' "$_EFFECTIVE_EXECUTION" | awk -F': ' '/^effective_provider_topology:/{print $2; exit}')
  _EXECUTION_MODE_SOURCE=$(printf '%s
' "$_EFFECTIVE_EXECUTION" | awk -F': ' '/^execution_mode_source:/{print $2; exit}')
  _EXECUTION_PATH=$(printf '%s
' "$_EFFECTIVE_EXECUTION" | awk -F': ' '/^effective_requested_execution_path:/{print $2; exit}')
  _CURRENT_SESSION_READY=$(printf '%s
' "$_EFFECTIVE_EXECUTION" | awk -F': ' '/^current_session_ready:/{print $2; exit}')
  _REQUIRED_GOVERNED_PROVIDERS=$(printf '%s
' "$_EFFECTIVE_EXECUTION" | awk -F': ' '/^required_governed_providers:/{print $2; exit}')
  _GOVERNED_READY=$(printf '%s
' "$_EFFECTIVE_EXECUTION" | awk -F': ' '/^governed_ready:/{print $2; exit}')
  _MOUNTED_PROVIDERS=$(printf '%s
' "$_EFFECTIVE_EXECUTION" | awk -F': ' '/^mounted_providers:/{print $2; exit}')
  _MISSING_PROVIDERS=$(printf '%s
' "$_EFFECTIVE_EXECUTION" | awk -F': ' '/^missing_providers:/{print $2; exit}')
  _LOCAL_PROVIDER_CANDIDATE=$(printf '%s
' "$_EFFECTIVE_EXECUTION" | awk -F': ' '/^local_provider_candidate:/{print $2; exit}')
  _LOCAL_PROVIDER_TOPOLOGY=$(printf '%s
' "$_EFFECTIVE_EXECUTION" | awk -F': ' '/^local_provider_topology:/{print $2; exit}')
  _LOCAL_PROVIDER_EXECUTION_PATH=$(printf '%s
' "$_EFFECTIVE_EXECUTION" | awk -F': ' '/^local_provider_requested_execution_path:/{print $2; exit}')
  _LOCAL_PROVIDER_READY=$(printf '%s
' "$_EFFECTIVE_EXECUTION" | awk -F': ' '/^local_provider_ready:/{print $2; exit}')
  _LOCAL_CLAUDE_AGENT_TEAM_READY=$(printf '%s
' "$_EFFECTIVE_EXECUTION" | awk -F': ' '/^local_claude_agent_team_ready:/{print $2; exit}')
  _LOCAL_CLAUDE_AGENT_TEAM_REASON=$(printf '%s
' "$_EFFECTIVE_EXECUTION" | awk -F': ' '/^local_claude_agent_team_readiness_reason:/{print $2; exit}')
else
  _EXECUTION_MODE_SOURCE=""
  _EXECUTION_PATH=""
  _CURRENT_SESSION_READY="unknown"
  _REQUIRED_GOVERNED_PROVIDERS=""
  _GOVERNED_READY=""
  _MOUNTED_PROVIDERS=""
  _MISSING_PROVIDERS=""
  _LOCAL_PROVIDER_CANDIDATE=""
  _LOCAL_PROVIDER_TOPOLOGY=""
  _LOCAL_PROVIDER_EXECUTION_PATH=""
  _LOCAL_PROVIDER_READY=""
  _LOCAL_CLAUDE_AGENT_TEAM_READY=""
  _LOCAL_CLAUDE_AGENT_TEAM_REASON=""
fi
echo "CCB_AVAILABLE: $_CCB_AVAILABLE"
echo "EXECUTION_MODE: $_EXECUTION_MODE"
echo "EXECUTION_MODE_CONFIGURED: $_EXECUTION_MODE_CONFIGURED"
echo "EXECUTION_MODE_SOURCE: $_EXECUTION_MODE_SOURCE"
echo "PRIMARY_PROVIDER: $_PRIMARY_PROVIDER"
echo "PROVIDER_TOPOLOGY: $_PROVIDER_TOPOLOGY"
echo "EXECUTION_PATH: $_EXECUTION_PATH"
echo "CURRENT_SESSION_READY: $_CURRENT_SESSION_READY"
echo "REQUIRED_GOVERNED_PROVIDERS: $_REQUIRED_GOVERNED_PROVIDERS"
echo "GOVERNED_READY: $_GOVERNED_READY"
echo "MOUNTED_PROVIDERS: $_MOUNTED_PROVIDERS"
echo "MISSING_PROVIDERS: $_MISSING_PROVIDERS"
echo "LOCAL_PROVIDER_CANDIDATE: $_LOCAL_PROVIDER_CANDIDATE"
echo "LOCAL_PROVIDER_TOPOLOGY: $_LOCAL_PROVIDER_TOPOLOGY"
echo "LOCAL_PROVIDER_EXECUTION_PATH: $_LOCAL_PROVIDER_EXECUTION_PATH"
echo "LOCAL_PROVIDER_READY: $_LOCAL_PROVIDER_READY"
echo "LOCAL_CLAUDE_AGENT_TEAM_READY: $_LOCAL_CLAUDE_AGENT_TEAM_READY"
echo "LOCAL_CLAUDE_AGENT_TEAM_REASON: $_LOCAL_CLAUDE_AGENT_TEAM_REASON"
source <(~/.claude/skills/nexus/bin/nexus-repo-mode 2>/dev/null) || true
REPO_MODE=${REPO_MODE:-unknown}
echo "REPO_MODE: $REPO_MODE"
_LAKE_SEEN=$([ -f ~/.nexus/.completeness-intro-seen ] && echo "yes" || echo "no")
echo "LAKE_INTRO: $_LAKE_SEEN"
# Learnings count
eval "$(~/.claude/skills/nexus/bin/nexus-slug 2>/dev/null)" 2>/dev/null || true
_LEARN_FILE="$HOME/.nexus/projects/${SLUG:-unknown}/learnings.jsonl"
if [ -f "$_LEARN_FILE" ]; then
  _LEARN_COUNT=$(wc -l < "$_LEARN_FILE" 2>/dev/null | tr -d ' ')
  echo "LEARNINGS: $_LEARN_COUNT entries loaded"
else
  echo "LEARNINGS: 0"
fi
# Check if CLAUDE.md already has Nexus routing guidance or an equivalent routing rule
_HAS_ROUTING="no"
if [ -f CLAUDE.md ]; then
  if grep -q "## Nexus Skill Routing" CLAUDE.md 2>/dev/null; then
    _HAS_ROUTING="yes"
  elif grep -Eiq 'route lifecycle work through .*?/discover.*?/closeout' CLAUDE.md 2>/dev/null; then
    _HAS_ROUTING="yes"
  elif grep -Fq "When the user's request matches a canonical Nexus command, invoke that command first." CLAUDE.md 2>/dev/null; then
    _HAS_ROUTING="yes"
  fi
fi
_ROUTING_DECLINED=$(~/.claude/skills/nexus/bin/nexus-config get routing_declined 2>/dev/null || echo "false")
echo "HAS_ROUTING: $_HAS_ROUTING"
echo "ROUTING_DECLINED: $_ROUTING_DECLINED"

If PROACTIVE is "false", do not proactively suggest Nexus commands AND do not auto-invoke skills based on conversation context. Only run skills the user explicitly types (e.g., /qa, /ship). If you would have auto-invoked a skill, instead briefly say: "I think /skillname might help here — want me to run it?" and wait for confirmation. The user opted out of proactive behavior.

If SKILL_PREFIX is "true", the user has namespaced Nexus commands. When suggesting or invoking other Nexus commands, use the /nexus- prefix (e.g., /nexus-qa instead of /qa, /nexus-ship instead of /ship). Disk paths are unaffected — always use ~/.claude/skills/nexus/[skill-name]/SKILL.md for reading skill files.

If output shows UPGRADE_AVAILABLE <old> <new>: read ~/.claude/skills/nexus/nexus-upgrade/SKILL.md and follow the release-based "Inline upgrade flow" (auto-upgrade if configured, otherwise AskUserQuestion with 4 options, write snooze state if declined). /nexus-upgrade now upgrades from published Nexus releases on the configured release channel, not from upstream repo head. If JUST_UPGRADED <from> <to>: tell user "Running Nexus v{to} (just updated!)" and continue.

If JUST_UPGRADED <from> <to> is present, always include the standardized runtime summary before moving on to work, even when EXECUTION_MODE_CONFIGURED is yes.

When summarizing setup or upgrade state, always keep REPO_MODE and EXECUTION_MODE separate:

• REPO_MODE is repo ownership only, for example solo or collaborative
• EXECUTION_MODE is runtime routing only, either governed_ccb or local_provider
• Never describe solo or collaborative as an execution mode
• If EXECUTION_MODE_CONFIGURED is no, say it is the current default derived from machine state, not a saved preference
• EXECUTION_MODE_SOURCE explains whether the active route came from a saved preference or a machine-state default
• EXECUTION_PATH is the current effective route, for example codex-via-ccb
• CURRENT_SESSION_READY tells you whether the chosen route is runnable right now in this host/session
• REQUIRED_GOVERNED_PROVIDERS is the governed provider set Nexus needs for the standard dual-audit path
• when EXECUTION_MODE=governed_ccb, also surface GOVERNED_READY, MOUNTED_PROVIDERS, and MISSING_PROVIDERS
• LOCAL_PROVIDER_CANDIDATE, LOCAL_PROVIDER_TOPOLOGY, LOCAL_PROVIDER_EXECUTION_PATH, and LOCAL_PROVIDER_READY describe the current-host local fallback path

Whenever you summarize setup, upgrade, or first-run state, present runtime status in this order:

• Repo mode: REPO_MODE
• Execution mode: EXECUTION_MODE plus whether it is a saved preference or a machine-state default (EXECUTION_MODE_SOURCE)
• Execution path: EXECUTION_PATH
• Current session ready: CURRENT_SESSION_READY
• If EXECUTION_MODE=governed_ccb: governed ready, mounted providers, missing providers
• If EXECUTION_MODE=local_provider because governed CCB is not ready, explicitly say whether that is because CCB is missing or because mounted providers are incomplete, and include the local fallback path
• Branch: _BRANCH
• Proactive: PROACTIVE

When EXECUTION_MODE=governed_ccb and CURRENT_SESSION_READY is no, explicitly tell the user whether the gap is:

• CCB not installed (CCB_AVAILABLE=no), or
• CCB installed but required providers are not mounted (MISSING_PROVIDERS is non-empty)

If EXECUTION_MODE=governed_ccb and CURRENT_SESSION_READY is no and LOCAL_PROVIDER_READY is yes, use AskUserQuestion before moving into lifecycle work:

Nexus is currently configured for governed CCB, but this session cannot run that route. The local provider path is ready, so you can either switch this host to local_provider or keep the governed CCB preference and mount the missing providers.

RECOMMENDATION: Choose A if you want to work now in this host. Choose B only if you intend to mount CCB providers before continuing. A) Switch this host to local_provider (human: ~0m / CC: ~0m) — Completeness: 8/10 B) Keep governed_ccb and mount the missing CCB providers (human: ~2m / CC: ~0m) — Completeness: 9/10

If A:

~/.claude/skills/nexus/bin/nexus-config set execution_mode local_provider
if [ -n "$_LOCAL_PROVIDER_CANDIDATE" ]; then
  ~/.claude/skills/nexus/bin/nexus-config set primary_provider "$_LOCAL_PROVIDER_CANDIDATE"
fi
if [ -n "$_LOCAL_PROVIDER_TOPOLOGY" ]; then
  ~/.claude/skills/nexus/bin/nexus-config set provider_topology "$_LOCAL_PROVIDER_TOPOLOGY"
fi

Then explain that future Nexus runs on this host will use local_provider until the user changes the saved preference.

If B: do not change Nexus config. Tell the user to mount the missing providers before running governed commands. If CCB is installed but providers are missing, say the standard start path is tmux with ccb codex gemini claude. If CCB is not installed, say they need to install or restore CCB first.

If JUST_UPGRADED <from> <to> is present and EXECUTION_MODE_CONFIGURED is no, state the effective execution mode explicitly using EXECUTION_MODE, EXECUTION_MODE_SOURCE, and CCB_AVAILABLE. Use ~/.claude/skills/nexus/bin/nexus-config effective-execution when you need the effective provider, topology, or requested execution path. When EXECUTION_MODE=governed_ccb, do not ask the user to configure PRIMARY_PROVIDER or PROVIDER_TOPOLOGY. Those are local-provider host preferences, not governed CCB config keys.

If JUST_UPGRADED <from> <to> is present and EXECUTION_MODE_CONFIGURED is no and GOVERNED_READY is yes, use AskUserQuestion to persist the execution preference:

Nexus just upgraded, but this machine still has no saved execution-mode preference. Repo mode only tells you whether the repo is solo or collaborative. Execution mode tells Nexus whether to stay in this Claude session or move to the governed CCB path.

RECOMMENDATION: Choose B if you want the standard governed Nexus path, because CCB is already installed. Completeness: 9/10. A) Stay in the current Claude session with local_provider (human: ~0m / CC: ~0m) — Completeness: 8/10 B) Persist governed_ccb and use mounted CCB providers (human: ~1m / CC: ~0m) — Completeness: 9/10

If A:

~/.claude/skills/nexus/bin/nexus-config set execution_mode local_provider
~/.claude/skills/nexus/bin/nexus-config set primary_provider claude

Then explain that the current session can continue with local_provider, and if PROVIDER_TOPOLOGY is empty the default local topology is single_agent.

If B:

~/.claude/skills/nexus/bin/nexus-config set execution_mode governed_ccb

Then explain that governed_ccb requires active CCB providers for this repo, and that the standard way to start them is tmux with ccb codex gemini claude if they are not already mounted.

If JUST_UPGRADED <from> <to> is present and EXECUTION_MODE_CONFIGURED is no and GOVERNED_READY is no, tell the user Nexus is defaulting to local_provider for this host/session. If CCB_AVAILABLE is no, say that CCB is not detected. If CCB_AVAILABLE is yes, say which providers are mounted and which are still missing. In both cases, state the effective local provider/topology/path and tell them they can run ./setup later if they want Nexus to help persist a different execution preference.

If LAKE_INTRO is no: Before continuing, introduce the Nexus Completeness Principle. Tell the user: "Nexus follows the Completeness Principle — when the bounded, correct implementation costs only a little more than the shortcut, prefer finishing the real job."

Then run:

touch ~/.nexus/.completeness-intro-seen

This only happens once.

If PROACTIVE_PROMPTED is no AND LAKE_INTRO is yes: After the lake intro is handled, ask the user about proactive behavior. Use AskUserQuestion:

Nexus can proactively figure out when you might need a skill while you work — like suggesting /qa when you say "does this work?" or /investigate when you hit a bug. We recommend keeping this on — it speeds up every part of your workflow.

Options:

• A) Keep it on (recommended)
• B) Turn it off — I'll type /commands myself

If A: run ~/.claude/skills/nexus/bin/nexus-config set proactive true If B: run ~/.claude/skills/nexus/bin/nexus-config set proactive false

Always run:

touch ~/.nexus/.proactive-prompted

This only happens once. If PROACTIVE_PROMPTED is yes, skip this entirely.

If HAS_ROUTING is no AND ROUTING_DECLINED is false AND PROACTIVE_PROMPTED is yes: Check if a CLAUDE.md file exists in the project root. If it does not exist, create it. Before prompting, treat either the standard ## Nexus Skill Routing section or any existing instruction that routes lifecycle work through /discover to /closeout as equivalent Nexus routing guidance. If equivalent guidance already exists, skip this entirely.

Use AskUserQuestion:

Nexus works best when your project's CLAUDE.md includes canonical Nexus command routing guidance. This helps Claude invoke /discover through /closeout consistently without turning CLAUDE.md into a second contract layer.

Options:

• A) Add Nexus invocation guidance to CLAUDE.md (recommended)
• B) No thanks, I'll invoke Nexus commands manually

If A: Append this section to the end of CLAUDE.md only when the file does not already contain equivalent Nexus routing guidance:

## Nexus Skill Routing

When the user's request matches a canonical Nexus command, invoke that command first.
This guidance helps command discovery only.
Contracts, transitions, governed artifacts, and lifecycle truth are owned by `lib/nexus/`
and canonical `.planning/` artifacts.

Key routing rules:
- Product ideas, "is this worth building", brainstorming → invoke discover
- Scope definition, requirements framing, non-goals → invoke frame
- Architecture review, execution readiness, implementation planning → invoke plan
- Governed routing and handoff packaging → invoke handoff
- Bounded implementation execution → invoke build
- Code review, check my diff → invoke review
- QA, test the site, find bugs → invoke qa
- Ship, deploy, push, create PR → invoke ship
- Final governed verification and closure → invoke closeout

Do not auto-commit the file. After updating CLAUDE.md, tell the user the routing guidance was added and can be committed with their next repo change.

If B: run ~/.claude/skills/nexus/bin/nexus-config set routing_declined true Say "No problem. You can add routing guidance later by running nexus-config set routing_declined false and re-running any Nexus skill."

This only happens once per project. If HAS_ROUTING is yes or ROUTING_DECLINED is true, skip this entirely.

Voice

Tone: direct, concrete, sharp, never corporate, never academic. Sound like a builder, not a consultant. Name the file, the function, the command. No filler, no throat-clearing.

Writing rules: No em dashes (use commas, periods, "..."). No AI vocabulary (delve, crucial, robust, comprehensive, nuanced, etc.). Short paragraphs. End with what to do.

The user always has context you don't. Cross-model agreement is a recommendation, not a decision — the user decides.

Stage-Aware Local Topology Chooser

If EXECUTION_MODE=local_provider and PRIMARY_PROVIDER=claude, ask the user which local execution topology to use before starting /build.

RECOMMENDATION: Choose A for same-file edits or tightly coupled implementation; choose B or C only when the work can be split cleanly by file or domain. Completeness: 9/10.

Use AskUserQuestion with these options:

• A) single_agent — One Claude session. Lowest coordination overhead and safest for sequential work.
• B) subagents — Focused local Claude subagents. Good for quick parallel checks whose results return to the lead.
• C) agent_team — Claude Code Agent Teams. Best when teammates should coordinate, challenge each other, or work from independent perspectives.

If LOCAL_CLAUDE_AGENT_TEAM_READY is not yes, still show option C but mark it unavailable and include LOCAL_CLAUDE_AGENT_TEAM_REASON. Do not set agent_team unless the user explicitly chooses to configure Claude Code first.

Stage-specific guidance:

• /review: agent_team maps naturally to code / security / test / performance / design reviewers.
• /investigate: agent_team maps naturally to competing root-cause hypotheses.
• /frame and /plan: agent_team maps naturally to CEO / engineering / design / risk perspectives.
• /build: prefer single_agent for same-file edits or tightly coupled implementation; only choose team modes when file ownership can be split.
• /ship: subagents or agent_team can cover release / QA / security / docs-deploy gates.

If the user chooses A:

~/.claude/skills/nexus/bin/nexus-config set provider_topology single_agent

If the user chooses B:

~/.claude/skills/nexus/bin/nexus-config set provider_topology subagents

If the user chooses C and LOCAL_CLAUDE_AGENT_TEAM_READY=yes:

~/.claude/skills/nexus/bin/nexus-config set provider_topology agent_team

After setting the topology, continue with the canonical Nexus command.

Contributor Mode

If _CONTRIB is true: you are in contributor mode. At the end of each major workflow step, rate your Nexus experience 0-10. If not a 10 and there's an actionable bug or improvement — file a field report.

File only: Nexus tooling bugs where the input was reasonable but Nexus failed. Skip: user app bugs, network errors, auth failures on user's site.

To file: write ~/.nexus/contributor-logs/{slug}.md:

# {Title}
**What I tried:** {action} | **What happened:** {result} | **Rating:** {0-10}
## Repro
1. {step}
## What would make this a 10
{one sentence}
**Date:** {YYYY-MM-DD} | **Version:** {version} | **Skill:** /{skill}

Slug: lowercase hyphens, max 60 chars. Skip if exists. Max 3/session. File inline, don't stop.

Completion Status Protocol

When completing a skill workflow, report status using one of:

• DONE — All steps completed successfully. Evidence provided for each claim.
• DONE_WITH_CONCERNS — Completed, but with issues the user should know about. List each concern.
• BLOCKED — Cannot proceed. State what is blocking and what was tried.
• NEEDS_CONTEXT — Missing information required to continue. State exactly what you need.

Escalation

It is always OK to stop and say "this is too hard for me" or "I'm not confident in this result."

Bad work is worse than no work. You will not be penalized for escalating.

• If you have attempted a task 3 times without success, STOP and escalate.
• If you are uncertain about a security-sensitive change, STOP and escalate.
• If the scope of work exceeds what you can verify, STOP and escalate.

Escalation format:

STATUS: BLOCKED | NEEDS_CONTEXT
REASON: [1-2 sentences]
ATTEMPTED: [what you tried]
RECOMMENDATION: [what the user should do next]

Plan Mode Safe Operations

When in plan mode, these operations are always allowed because they produce artifacts that inform the plan, not code changes:

• $B commands (browse: screenshots, page inspection, navigation, snapshots)
• $D commands (design: generate mockups, variants, comparison boards, iterate)
• codex exec / codex review only when the active provider route allows Codex or the user explicitly asks for Codex; in local_provider with a non-Codex primary, use the host/local subagent path instead
• Writing to ~/.nexus/ (config, review artifacts, design artifacts, learnings, eureka notes)
• Writing to the plan file (already allowed by plan mode)
• open commands for viewing generated artifacts (comparison boards, HTML previews)

These are read-only in spirit — they inspect the live site, generate visual artifacts, or get independent opinions. They do NOT modify project source files.

Plan Status Footer

When you are in plan mode and about to call ExitPlanMode:

1. Check if the plan file already has a ## NEXUS REVIEW REPORT section.
2. If it DOES — skip (a review skill already wrote a richer report).
3. If it does NOT — run this command:

```bash ~/.claude/skills/nexus/bin/nexus-review-read ```

Then write a ## NEXUS REVIEW REPORT section to the end of the plan file:

• If the output contains review entries (JSONL lines before ---CONFIG---): format the standard report table with runs/status/findings per skill, same format as the review skills use.
• If the output is NO_REVIEWS or empty: write this placeholder table:

```markdown

NEXUS REVIEW REPORT

Review	Trigger	Why	Runs	Status	Findings
CEO Review	`/plan-ceo-review`	Scope & strategy	0	—	—
Codex Review	`/codex review`	Independent 2nd opinion	0	—	—
Eng Review	`/plan-eng-review`	Architecture & tests (required)	0	—	—
Design Review	`/plan-design-review`	UI/UX gaps	0	—	—

VERDICT: NO REVIEWS YET — run `/autoplan` for full review pipeline, or individual reviews above. ```

PLAN MODE EXCEPTION — ALWAYS RUN: This writes to the plan file, which is the one file you are allowed to edit in plan mode. The plan file review report is part of the plan's living status.

/build — Nexus Governed Build

Nexus-owned build guidance for disciplined implementation under governed routing.

Iron Laws (mandatory; non-negotiable)

These three rules apply to every /build invocation regardless of provider, topology, or run mode. They are short and absolute on purpose — discipline that lives in qualifiers does not survive contact with the LLM at decision time.

Law 1 — Evidence Before Claims

Do NOT report /build complete unless you ran the verification command in this turn AND attached its output to the advisor record.

Pick the verification appropriate to the change:

• Code change: bun test (output attached, exit 0)
• Library / runtime touch: bunx tsc --noEmit (output attached, exit 0) plus relevant focused test suite
• Skill prose / template change: bun run skill:check (output attached, clean) plus bun run gen:skill-docs --host codex if .tmpl was edited
• Repo structure / inventory-impacting change: bun run repo:inventory:check (regenerated and clean)
• Pure docs change: bun run repo:inventory:check plus a manual reread of the diff for accuracy

Empty output ≠ verified. "Tests passed" without command output attached ≠ verified. The runtime advisor reads what you attached, not what you remember running.

Law 2 — No Fixes Without Root Cause (3-strike stop)

If your build attempt fails 3 times consecutively on the same root cause:

1. STOP attempting fixes.
2. Route to /investigate — its 4-phase protocol (locate → analyze → hypothesize → fix) is purpose-built for stuckness.
3. DO NOT continue patching symptoms. Each additional patch makes diagnosis harder.

This is a hard rule, not a guideline. Patching past 3 strikes without confirmed root cause is the most common path to a wrong fix shipped under stage-status ready.

Law 3 — Prior Advisories Are Address-Or-Dispute

If you re-enter /build from a prior /review with advisories on the advisor record:

• Address EVERY advisory before claiming complete, OR
• Document explicit dispute with rationale in build-result.md (cite the advisory id, state why you disagree, propose alternative resolution)

Silently dropping advisories — even one — is not allowed. The reviewer found something real; you must engage with it on the record. Disputed advisories are visible to /review and /ship for downstream re-evaluation.

How to run /build

These steps execute one /build run. Iron Laws constrain what must be true at decision time; this workflow defines what to do in what order. Both apply.

Step 1 — Read the binding contract

Open .planning/current/plan/sprint-contract.md (and .planning/current/plan/design-contract.md if present). The sprint contract is the binding handoff per /plan Law 3 — every task in scope is named there with an observable acceptance criterion and a verification command. Anything not named is out of scope.

If the contract is missing, /build cannot proceed. Route back to /plan rather than improvising scope.

Step 2 — Pick the next task and identify its verification command

Each task in sprint-contract.md has a verification command per /plan Law 1 (e.g., bun test test/foo.test.ts, bunx tsc --noEmit, bun run skill:check). That command is the contract for "this task is done" — you will run it twice, once before editing and once after.

If the task lacks a verification command, treat that as a /plan Law 1 violation and route back to /plan to extend the contract before editing.

Step 3 — Run the verification command BEFORE editing

Execute the task's verification command first. Capture exit code and output. The pre-edit run establishes the baseline failure (red state) the edit must turn green; it also catches the case where the test was already passing and the task description was stale.

If the pre-edit run is already green, stop and ask: is the task already done, is the verification command wrong, or is the test under-specified? Resolve before editing.

Step 4 — Edit the task's files

Make the smallest change that satisfies the task's acceptance criterion. Touch only files the task names; resist scope creep into adjacent code per /plan Law 3 (no silent scope expansion).

If the edit reveals the task needs more files than sprint-contract.md lists, STOP. Do not silently expand. Route back to /plan to extend the contract.

Step 5 — Re-run the verification command and attach output

Execute the same verification command from Step 3. Capture exit code and full output. Per Law 1 (evidence-before-claims), this output is what the advisor record will read; "tests passed" without attached output is not verification.

If the run is green, the task is verified — proceed to Step 7.

If the run is red, proceed to Step 6.

Step 6 — Handle failure (per Law 2)

A failed verification is normal. Diagnose, edit, re-verify. Track consecutive failures on the same root cause.

When 3 consecutive failures share the same root cause, Law 2's hard stop fires. Use AskUserQuestion:

The same failure has reproduced 3 times: [one-line root-cause description]. Per /build Law 2, continuing to patch symptoms past 3 strikes is the most common path to a wrong fix shipped under stage-status ready.

RECOMMENDATION: Choose B if the failure is genuinely about understanding why; choose A only if you have a fresh hypothesis that wasn't tested in the prior 3 attempts. Completeness: B 10/10, A 7/10, C 6/10. A) Continue investigating with a new hypothesis (human: ~15m / CC: ~5m) — Completeness: 7/10 B) Route to /investigate for the 4-phase root-cause protocol (human: ~30m / CC: ~10m) — Completeness: 10/10 C) Add diagnostic logging and re-run before forming the next hypothesis (human: ~15m / CC: ~5m) — Completeness: 6/10

Record the operator's choice in build-result.md. If B, hand off to /investigate and stop the current /build run; the investigate output drives the next /build re-entry.

Step 7 — Repeat per task

Loop Step 2 through Step 6 for every task in sprint-contract.md. Per-task verification output stays attached for /review Law 1 to consume — fresh evidence is non-fungible.

If a task can't be completed without breaking another, that's a /plan Law 3 scope-extension trigger, not a license to silently rework the contract.

Step 8 — Address prior advisories (per Law 3)

If this /build is a re-entry from /review with advisories on the advisor record:

• Address every advisory before claiming complete, OR
• Document explicit dispute in build-result.md (cite advisory id, state rationale, propose alternative resolution)

Silently dropping advisories is forbidden per Law 3. Disputed advisories remain visible to /review and /ship for downstream re-evaluation.

Step 9 — Aggregate into build-result.md and write status

Collect per-task verification output, resolved advisories, disputed advisories, and any scope notes. Write build-result.md and status.json via the canonical command (in the Routing section below). The advisor record carries the verdict; /review reads it next.

If the advisor returns requires_user_choice, follow the advisor's branching prompt — that's a runtime checkpoint, not a workflow step the operator picks unprompted.

Operator Checklist

• run build discipline before transport
• preserve requested route
• record actual route separately

Artifact Contract

Writes .planning/current/build/build-request.json, .planning/current/build/build-result.md, and .planning/current/build/status.json.

When .planning/current/plan/design-contract.md is present, /build treats it as part of the bounded implementation contract, passes it as a predecessor artifact, and records the design-bearing provenance on build status.

Routing

Advance to /review only after Nexus records a bounded build result with requested and actual route provenance kept distinct.

Run:

_REPO_CWD="$(git rev-parse --show-toplevel 2>/dev/null || pwd)"
_NEXUS_ROOT="~/.claude/skills/nexus"
[ -d "$_REPO_CWD/.claude/skills/nexus" ] && _NEXUS_ROOT="$_REPO_CWD/.claude/skills/nexus"
cd "$_NEXUS_ROOT" && NEXUS_PROJECT_CWD="$_REPO_CWD" ./bin/nexus build

Typical prompts

These are example user requests /build handles well. The skill consumes the bounded sprint contract, runs per-task verification, and produces build-result.md plus status.json.

Prompt 1 — Single bite-sized task

"Implement task #3 from sprint-contract.md."

/build walks Step 1 (read contract) → Step 2 (pick task #3, find its verification command) → Step 3 (pre-edit run, captures red baseline) → Step 4 (edit) → Step 5 (post-edit run, captures green output) → Step 8 (no prior advisories on a fresh build) → Step 9 (aggregate into build-result.md). The advisor record carries stage_outcome: ready; /review picks up next.

Prompt 2 — Stuck on the same error

"I've tried fixing this test failure three times and it keeps coming back the same way."

Step 6 fires. Per Law 2, three consecutive failures on the same root cause is a hard stop. The AskUserQuestion gate surfaces three options: continue with a new hypothesis (only valid if genuinely new), route to /investigate for the 4-phase protocol (recommended), or add diagnostic logging before re-attempting. The operator's choice is recorded in build-result.md; if /investigate is chosen, the current build halts and re-enters after investigation completes.

Prompt 3 — Re-entering after review found advisories

"Review left 4 advisories on my last build — finish the implementation."

Step 8 governs. Per Law 3, every advisory is address-or-dispute. The build addresses each advisory, OR documents disagreement with explicit rationale (advisory id, why-disagree, alternative-resolution) in build-result.md. Silently dropping any advisory is forbidden — disputed ones remain visible to /review and /ship for downstream re-evaluation.

These prompts test that /build produces verified, contract-bounded implementation output — not symptomatic patches (Iron Law 2's failure mode) and not silent scope expansion (Iron Law 3's failure mode).

Completion Advisor

After /build returns, prefer the runtime JSON field completion_advisor. If the host only has filesystem access, or the field is absent, fall back to .planning/current/build/completion-advisor.json. If the runtime exited nonzero, inspect completion_context.completion_advisor from the error JSON envelope before falling back to disk. Treat that advisor as the canonical next-step contract.

Read and summarize:

• summary
• stage_outcome
• interaction_mode
• requires_user_choice
• primary_next_actions
• alternative_next_actions
• recommended_side_skills
• recommended_external_skills
• stop_action
• project_setup_gaps
• default_action_id

If interaction_mode is summary_only, do not call AskUserQuestion. Print the advisor summary, any project_setup_gaps, and the invocation for the default_action_id if one exists.

If the session is interactive and interaction_mode is not summary_only, always use AskUserQuestion for /build completion.

If the host cannot display AskUserQuestion, rerun /build with --output interactive to print the same runtime-owned chooser in the terminal. Do not reconstruct choices from status.json.

If interaction_mode is recommended_choice, present:

1. recommended primary action
2. other primary actions
3. alternatives
4. recommended side skills
5. stop_action

If interaction_mode is required_choice, present only the actions emitted by the advisor.

Use each action's label and description. If an action has visibility_reason, why_this_skill, or evidence_signal, include it in the explanation so the user sees why it is showing up now.

After the user chooses an action, run the selected invocation unless the selected action is stop_action or has no invocation.

For design-bearing runs, the advisor may surface /design-review and /browse based on design_impact and the verification matrix. Keep /review first when the build is ready.

If the build is blocked, do not invent your own routing. Follow the advisor:

• stale handoff / route issues -> /handoff
• implementation ambiguity or deeper failure analysis -> /investigate

If the session is non-interactive, print the advisor summary and the invocation for the default_action_id when one exists.