scaffold-init

name	scaffold-init
description	Compile a target project's signals into an executable oracle — the first Servo Compile step of servo's Evaluation-Driven Development engine. Probes the target for signals (tests, lint, CI, language) and drops a tailored `oracle.sh`, `.servo/install.json` manifest, and `.servo/refinement-todo.md` deferred-decisions list.

/servo:scaffold-init

Compile a target project's signals into a runnable Tier-0 oracle — the first Servo Compile step (servo is an Evaluation-Driven Development engine; see docs/product-vision.md). End state: the project gains a runnable oracle.sh, a machine-readable install manifest, and an explicit list of deferred decisions for the dev to resolve.

When to use this skill

Use when the user is asking to install servo on a project for the first time (or re-install with --force). The helper is at ${PLUGIN_ROOT}/skills/scaffold-init/scaffold.py. Tier 1 (agent-loop driver) and Tier 2 (hooks + worktree race) are forward-looking — only Tier 0 is shipped in spec 001.

This skill is the scaffolder. It does not run loops, install hooks, or score code at runtime. Those are future siblings (/servo:agent-loop, /servo:oracle-hook, /servo:variant-race, /servo:quality-gate).

Q&A flow

Ask the following five questions in order. Each is independently skippable — if the user says "skip", says "I don't know", or doesn't give a clear answer, omit the corresponding flag and let the helper fall back to filesystem inference. Never invent answers. Skipping every question is a legitimate, supported path (see "Pure inference" below).

1. Project type

"Is this project a service, a library, a plugin, or are you unsure?"

• service → component bias toward CI checks
• library → component bias toward test coverage
• plugin → component bias toward shape-of-installable
• unsure / skip → no bias; rely on filesystem signals alone

This answer is informational at slice 001-05 (the helper doesn't yet honor a --project-type flag). Recorded for future Tier-1+ slices where it will tune weight defaults.

2. Tier

"Which tier do you want? Tier 0 only (oracle), Tier 0 + 1 (oracle + agent-loop driver), or all three (Tier 0 + 1 + 2 with hooks + worktree race)?"

• Tier 0 → ships now. Drops oracle.sh + manifest + refinement-todo.
• Tier 1 → future. If the user picks this, tell them: "Tier 1 templates ship in a future spec (003-agent-loop). Tier 0 will install now; come back when 003 lands."
• Tier 2 → future, same handling — point at spec 004 (oracle-hook) and 005 (variant-race).
• skip → assume Tier 0.

3. Loop guardrails

"Use default loop guardrails (max-iterations=5, cost-ceiling=$2), or set custom values?"

If the user picks custom, ask for the iteration cap and the cost ceiling separately. Record both. Tier 1 is not yet shipped, so the values are informational at this slice.

If the user picks defaults or skips, omit and continue.

4. Hook installation

"Install the Claude Code hook now (Tier 2 only)? yes / no / skip"

Tier 2 is not yet shipped, so this is informational. If the user says yes, note that the hook installer will be implemented by spec 004 (oracle-hook) and install Tier 0 anyway. If no or skip, continue.

5. Existing servo install

If <target>/.servo/install.json already exists, ask:

"An existing servo install was detected (.servo/install.json present). Proceed with --force (overwrite the oracle, rewrite the manifest, rewrite the refinement-todo) — or abort?"

• proceed → invoke with --force.
• abort → exit cleanly without calling the helper.

If .servo/install.json is absent, skip this question silently.

Pure inference

If the user skips every question, invoke the helper with no flags:

python3 "${PLUGIN_ROOT}/skills/scaffold-init/scaffold.py" <target>

This is the pure inference path — equivalent to running the helper directly. The output is fully driven by what's on disk in <target>: detected test framework, lint configs, CI files, language. Skipping all is not a degraded mode; it's the documented baseline.

Refusal handling

If the helper exits with error: oracle.sh already present (return code 1), the install was refused — not failed. The helper detected an existing scaffold and refused to clobber it.

When this happens:

1. Surface the helper's stderr message to the user verbatim. Do not paraphrase or summarize away the --force hint.
2. Ask the user whether to re-scaffold with --force. This overwrites oracle.sh, rewrites .servo/install.json, and rewrites .servo/refinement-todo.md. It does not delete the rest of .servo/ (per slice 001-01's --force contract).
3. Do NOT silently retry with --force. Re-running automatically would destroy in-progress work without consent.

If the helper exits with return code 2 (environment error — target missing, target not a directory, template missing), surface the message verbatim and stop. --force will not help.

How to invoke

# Pure inference — all questions skipped:
python3 "${PLUGIN_ROOT}/skills/scaffold-init/scaffold.py" <target>

# After question 5 = proceed (existing install present):
python3 "${PLUGIN_ROOT}/skills/scaffold-init/scaffold.py" <target> --force

# Audit only (no scaffolding) — useful for previewing detection results:
python3 "${PLUGIN_ROOT}/skills/scaffold-init/scaffold.py" detect <target>

<target> must be an existing directory. The helper does not create parent directories.

After the install

When the helper exits 0, three files have landed in the target:

• <target>/oracle.sh — runnable, executable. The user can bash oracle.sh to score now.
• <target>/.servo/install.json — manifest the future runtime skills (002–005) will read.
• <target>/.servo/refinement-todo.md — explicit list of deferred decisions: at minimum a Threshold entry, plus Weights and Ambiguous test runner when applicable.

Tell the user where these landed and invite them to scan the refinement-todo before their next commit.

Examples

Pure inference, no questions asked:

user: set up servo on this project
assistant: [asks Q1–Q5 in order, user skips each]
        → python3 .../scaffold.py /path/to/repo
        → "servo: installed tier-0 at /path/to/repo"

Existing install, proceed:

user: set up servo here
assistant: [asks Q5: existing install detected — proceed or abort?]
user: proceed
assistant: → python3 .../scaffold.py /path/to/repo --force

Existing install, helper refuses (user didn't get question 5):

assistant: → python3 .../scaffold.py /path/to/repo
       stderr: error: oracle.sh already present at .../oracle.sh; re-run with --force to overwrite
assistant: [surfaces the message verbatim to the user, asks whether to --force, does NOT silently retry]