/build

/build <change>

Build uses one model-facing command:

claude-foundation advance <change> --through build

The coordinator validates the agreement, creates or synchronizes the isolated workspace, compiles task dependencies, accounts for active leases, and returns one protocol-v5 action. After doing that action, the agent calls the exact resume route. It never reconstructs a sandbox → packet → plan → dispatch chain.

The six actions

Action	Meaning
EDIT	Implement only the returned task(s), workspace, and allowed paths; run the listed focused checks once
REPAIR	Apply one complete dependency-ordered repair batch, then resume
RUN_EXTERNAL	Run the one configured boundary operation
WAIT	A live resource/external owner must finish; state is preserved
ASK_USER	A material choice or authority is genuinely missing
DONE	The requested Build target is reached

Every non-done action names the cause, responsible actor, safe alternatives, preserved state, and exact resume command. Automatic recovery stays inside the agent’s current authority; the harness never turns a stale lease or repeated execution into a pass.

Isolation and concurrency

Product writes are allowed only in the exact workspace and paths returned by EDIT. Shell mutation must anchor itself to that workspace; on Claude Code the phase guard pins the shell’s reported directory as that anchor when it is already inside the workspace. A worktree contains tracked files only; configure sandbox.setupCommand or a per-repository setup command when dependencies must be installed. Sandbox creation prints a NOTE with the exact snippet when a lockfile is present and no setup command is declared; linking or copying the checkout’s node_modules into the workspace is refused.

The phase hook and claude-foundation exec use the same containment policy. They reject absolute outside operands, later directory escapes, and writes through symlinks outside the workspace; exec derives the phase from runtime state and starts Build children in the canonical workspace. This is cooperative containment, so the host still owns process isolation for indirect effects.

Parallel mode returns only independent tasks and lease instructions. The host starts every successfully leased worker before waiting, observes the writes, and resumes the same advance command. Primitive sandbox, packet, agents plan, and agents dispatch commands remain available under help --all for operator diagnostics and host integrations.

New behavior discovered during Build

Do not edit several OpenSpec ledgers by hand. Submit one semantic amendment:

claude-foundation change amend <change> <amendment.json> --consume-amendment

The compiler preserves completed tasks and manual sections, validates the new agreement transactionally, and returns to advance. updateTasks may extend claim coverage but cannot replace an existing outcome or verification command; add a new task when that contract changes. Permission-bound cloud, secret, Terraform, deployment, or restart work becomes a typed external operation; Build never asks for credentials.

DONE at Build does not prove or land the change.