Build

Execute the implementation plan for "$ARGUMENTS" task-by-task, following test-driven development discipline.

Arguments. $ARGUMENTS may contain the project name and optional flags. Take the first token as <project> and treat --skip-checks as a flag; never include flags in file paths. All paths below use <project>. If --skip-checks is present, skip the prerequisite check and, before writing any artifact, append one line to .singularskills/log.jsonl: {"ts":"<ISO timestamp>","skill":"development-build","workflow":"development","phase":2,"project":"<project>","event":"skipped","artifact":"02-build.md","note":"<reason or \"none given\">"}.

Prerequisites

Part of a workflow. This skill is phase 2 (Build) of the Plan-Build-Test-Ship workflow (development); cross-domain workflows run it too. First check .singularskills/log.jsonl for an open run for this project: a run-started line with "project":"<project>" and no later run-finished line for the same workflow and project. If one exists, the conductor is running you: continue here. Otherwise, if the user asked to start, run, continue or resume a process or workflow rather than this one step, do not continue here: invoke the workflow skill with the workflow the user asked for, or development when they named none, followed by <project>; it runs this phase in order, asks before it writes and records the run. Otherwise continue here: a later phase runs on its own, behind its gate.

Stack. Before you build, test, lint, run or generate code, read the Stack section of the project's AGENTS.md, or of CLAUDE.md when AGENTS.md has none. Use its commands exactly as written, its layout for where files go and its rules as requirements. If it names a profile, also read the file <profile>.md in the stacks folder of this skill's bundled references for the full commands, layout and rules; the project's own keys win where both speak. If there is no Stack section, run the singular-detect skill, state what you inferred in one line, and offer to write the section with singular-init. Never assume a package manager, test runner or formatter the project did not declare.

Run this skill's gate before writing: sh <this skill's folder>/scripts/gate.sh <project> <project root>, where <project root> is the folder that contains .singularskills/ (use . when you are already there). If it exits non-zero, stop and tell the user what it printed, unless --skip-checks was given (see Arguments). On a refusal, before you stop, append this line to .singularskills/log.jsonl (create the folder and file if missing): {"ts":"<ISO timestamp>","skill":"development-build","workflow":"development","phase":2,"project":"<project>","event":"refused","artifact":"02-build.md","note":"<what the gate printed>"}. Once the gate has passed, or under --skip-checks once you have appended the skipped line, append this line before you start work: {"ts":"<ISO timestamp>","skill":"development-build","workflow":"development","phase":2,"project":"<project>","event":"started","artifact":"02-build.md","note":""}.

Read .singularskills/development/<project>/01-plan.md. If this file does not exist, tell the user:

No plan exists for "<project>". Run /development-plan <project> first, or use --skip-checks to bypass.

Process

For each task in the plan:

1. Write the failing test first:

   • Write the test that verifies the task's expected behavior
   • Run the test suite — confirm the new test fails
   • If it passes without implementation, the test isn't testing anything — rewrite it

2. Implement the minimal code to pass:

   • Write only what's needed to make the failing test pass
   • Don't add features, refactor, or "improve" beyond the task scope
   • Follow existing codebase patterns and conventions

3. Verify:

   • Run the full test suite — all tests must pass
   • If other tests broke, fix them before moving on

4. Commit:

   • Stage the relevant files
   • Write a clear commit message following the project's convention

5. Log progress — after each task, append to the execution log:

   • Task name and status (completed/skipped/blocked)
   • Commit hash
   • Any issues encountered

6. Write the artifact to .singularskills/development/<project>/02-build.md

References

• references/stacks/bun-react-ts.md and references/stacks/rust-gpui.md: the shipped stack profiles

Output

The execution log written to .singularskills/development/<project>/02-build.md. Present a summary to the user highlighting:

• Tasks completed vs. total
• All commits made
• Any issues or deviations from the plan

Record the run. After you have written the artifact, append this line to .singularskills/log.jsonl (the started line of Prerequisites, with "event":"finished"): {"ts":"<ISO timestamp>","skill":"development-build","workflow":"development","phase":2,"project":"<project>","event":"finished","artifact":"02-build.md","note":""}.

Open the artifact with this frontmatter (agent is the agent you run in, or unknown; gate is passed when the gate ran clean and skipped under --skip-checks):

---
skill: development-build
workflow: development
phase: 2
project: <project>
started: <ISO timestamp>
finished: <ISO timestamp>
agent: <the agent you run in, or "unknown">
gate: <passed|skipped>
---

End the artifact with ## Decisions and ## Open questions, in this shape:

## Decisions
- <what was chosen> — <why> — <what was rejected>

## Open questions
- <what the next phase or a reviewer must settle>