Experiment

Preamble (run first)

# --- GENERATED PREAMBLE START ---
_PROJECT_ROOT=$(git rev-parse --show-toplevel 2>/dev/null || pwd)
if ! git rev-parse --show-toplevel >/dev/null 2>&1; then
  echo "WARNING: Not inside a git repository. Files will be written to $(pwd)."
fi
mkdir -p ~/.rstack/sessions ~/.rstack/analytics "$_PROJECT_ROOT/.rstack" "$_PROJECT_ROOT/results"
touch ~/.rstack/sessions/"$PPID"
find ~/.rstack/sessions -mmin +120 -type f -delete 2>/dev/null || true
_SESSIONS=$(find ~/.rstack/sessions -mmin -120 -type f 2>/dev/null | wc -l | tr -d ' ')
_RSTACK_DIR="$(cd "$(dirname "$0")/.." 2>/dev/null && pwd || echo "$HOME/.claude/skills/rstack")"
_RSTACK_CONFIG="$_RSTACK_DIR/bin/rstack-config"
_UPD=$("$_RSTACK_DIR/bin/rstack-update-check" 2>/dev/null || true)
[ -n "$_UPD" ] && echo "$_UPD" || true
_VENUE=$("$_RSTACK_CONFIG" get venue 2>/dev/null || echo "arxiv")
_COMPUTE=$("$_RSTACK_CONFIG" get compute_preferred 2>/dev/null || echo "modal")
_PROACTIVE=$("$_RSTACK_CONFIG" get proactive 2>/dev/null || echo "true")
_CHECKPOINT=$("$_RSTACK_CONFIG" get experiment_checkpoint 2>/dev/null || echo "3")
_TEL=$("$_RSTACK_CONFIG" get telemetry 2>/dev/null || echo "off")
_TEL_PROMPTED=$([ -f ~/.rstack/.telemetry-prompted ] && echo "yes" || echo "no")
_BRANCH=$(git branch --show-current 2>/dev/null || echo "unknown")
echo "PROJECT_ROOT: $_PROJECT_ROOT"
echo "BRANCH: $_BRANCH"
echo "VENUE: $_VENUE"
echo "COMPUTE: $_COMPUTE"
echo "PROACTIVE: $_PROACTIVE"
echo "CHECKPOINT_INTERVAL: $_CHECKPOINT"
if [ ! -f ~/.rstack/.setup-complete ]; then
  echo "NEEDS_SETUP"
fi
_TEL_START=$(date +%s)
_SESSION_ID="$$-$(date +%s)"
echo "TELEMETRY: ${_TEL:-off}"
echo "TEL_PROMPTED: $_TEL_PROMPTED"
if [ "$_TEL" != "off" ]; then
  echo '{"skill":"experiment","ts":"'$(date -u +%Y-%m-%dT%H:%M:%SZ)'","repo":"'$(basename "$(git rev-parse --show-toplevel 2>/dev/null)" 2>/dev/null || echo "unknown")'"}'  >> ~/.rstack/analytics/skill-usage.jsonl 2>/dev/null || true
fi
if [ "$_TEL" != "off" ]; then
  echo '{"skill":"experiment","ts":"'$(date -u +%Y-%m-%dT%H:%M:%SZ)'","session_id":"'"$_SESSION_ID"'","rstack_version":"'"$(cat "$_RSTACK_DIR/VERSION" 2>/dev/null | tr -d "[:space:]" || echo "unknown")"'"}'  > ~/.rstack/analytics/.pending-"$_SESSION_ID" 2>/dev/null || true
fi
for _PF in $(find ~/.rstack/analytics -maxdepth 1 -name '.pending-*' 2>/dev/null); do
  if [ -f "$_PF" ]; then
    _PF_BASE="$(basename "$_PF")"
    _PF_SID="${_PF_BASE#.pending-}"
    [ "$_PF_SID" = "$_SESSION_ID" ] && continue
    if [ "$_TEL" != "off" ] && [ -x "$_RSTACK_DIR/bin/rstack-telemetry-log" ]; then
      "$_RSTACK_DIR/bin/rstack-telemetry-log" --event-type skill_run --skill _pending_finalize --outcome unknown --session-id "$_SESSION_ID" 2>/dev/null || true
    fi
    rm -f "$_PF" 2>/dev/null || true
  fi
  break
done
eval "$("$_RSTACK_DIR/bin/rstack-slug" 2>/dev/null)" 2>/dev/null || true
echo "SLUG: ${SLUG:-unknown}"
# --- GENERATED PREAMBLE END ---

If output shows UPGRADE_AVAILABLE : read rstack-upgrade/SKILL.md and follow the "Inline Upgrade Flow". Then continue with this skill. If output shows JUST_UPGRADED : tell user "Running RStack v{to} (just updated!)" and continue.

If output shows NEEDS_SETUP: tell user "Modal not configured. Running /setup first..." Read setup-skill/SKILL.md and follow it inline.

If TEL_PROMPTED is no: Ask the user about telemetry. Use AskUserQuestion:

> Help RStack get better! Community mode shares usage data (which skills you use, > how long they take, crash info) with a stable device ID so we can track trends > and fix bugs faster. No code, file paths, or repo names are ever sent. > Change anytime with rstack-config set telemetry off.

Options:

• A) Help RStack get better! (recommended)
• B) No thanks

If A: run rstack-config set telemetry community

If B: ask a follow-up: > How about anonymous mode? Just a counter that helps us know if anyone's out there.

Options:

• A) Sure, anonymous is fine
• B) No thanks, fully off

If B→A: run rstack-config set telemetry anonymous If B→B: run rstack-config set telemetry off

Always run:

touch ~/.rstack/.telemetry-prompted

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

Important: Note the PROJECT_ROOT value from the preamble output. All file paths below are relative to this project root directory. Work products (idea.md, experiment-plan.md, results/, train.py) go at the project root. Plumbing (.rstack/experiments.jsonl) goes in the .rstack/ subdirectory.

---

Step 0: Check Compute

Verify Modal is available and authenticated:

command -v modal >/dev/null 2>&1 && echo "MODAL_INSTALLED" || echo "MODAL_MISSING"
modal token info >/dev/null 2>&1 && echo "MODAL_AUTH_OK" || echo "MODAL_AUTH_FAIL"

• If MODAL_MISSING: tell user "Modal not installed. Run pip install modal" and STOP.
• If MODAL_AUTH_FAIL: tell user "Modal not authenticated. Run ! modal token new" and STOP.
• If both OK: proceed.

---

Step 1: Understand the Research Goal

Read context in this priority order:

1. refined-idea.md (best — from /novelty-check, has sharp hypothesis)
2. idea.md (good — raw idea)
3. Ask user directly (if neither file exists)

Also read if available:

• novelty-assessment.md — tells us what baselines to compare against
• experiment-plan.md — previous plan from a prior run
• .rstack/experiments.jsonl — prior experiment results (we're continuing)

---

Step 2: Experiment Planning

Design the experiment before writing any code. Use WebSearch to find:

• Appropriate datasets for this research area (HuggingFace datasets preferred)
• Standard baselines to compare against
• Common evaluation metrics for this task

Write an experiment plan to experiment-plan.md at the project root:

# Experiment Plan

## Objective
{What we're testing, in one sentence}

## Dataset
{Name, source (HuggingFace/URL), size, format}

## Model Architecture
{What we're building/modifying}

## Training Protocol
{Optimizer, learning rate, batch size, epochs, schedule}

## Baselines
{What we compare against — at minimum, one existing method}

## Evaluation Metrics
{Primary metric + secondary metrics}

## Ablations (if applicable)
{What components to test individually}

Use AskUserQuestion: > Here's the experiment plan. Review and approve before I generate code? > > A) Looks good — generate the code > B) Modify — I want to change something > C) Use a different dataset / approach

---

Step 3: Code Generation

Generate experiment code in the project directory. The entry point must be train.py (this is what preflight and modal run execute). Create additional modules as needed for clean code organization (e.g., models.py, data.py, utils.py, evaluate.py). Also generate requirements.txt.

Helper modules don't need Modal decorators or argparse. They're imported by train.py. Only the entry point needs the mandatory rules below.

Mandatory rules for train.py (the entry point):

1. argparse interface:

``python parser = argparse.ArgumentParser() parser.add_argument("--data_dir", type=str, default="./data") parser.add_argument("--smoke_test", action="store_true") parser.add_argument("--output_dir", type=str, default="/output") ``

1. Smoke test mode: When --smoke_test is passed:

• Use only 10% of data or 1000 samples (whichever smaller)
• Max 2 epochs
• Skip expensive operations (large evaluations, visualization generation)
• Still produce output files so the pipeline can be tested end-to-end

1. Output contract: ALL outputs go to the --output_dir (default /output/):

``python os.makedirs(args.output_dir, exist_ok=True) # Save metrics with open(os.path.join(args.output_dir, "metrics.json"), "w") as f: json.dump(metrics, f, indent=2) # Save figures plt.savefig(os.path.join(args.output_dir, "loss_curve.png")) ``

1. Reproducibility:

``python import random, numpy as np, torch SEED = 42 random.seed(SEED) np.random.seed(SEED) torch.manual_seed(SEED) if torch.cuda.is_available(): torch.cuda.manual_seed_all(SEED) ``

1. Data validation: At the start, print what's in the data directory and verify files exist:

``python print(f"Data directory: {args.data_dir}") print(f"Contents: {os.listdir(args.data_dir)}") assert os.path.exists(args.data_dir), f"Data dir not found: {args.data_dir}" ``

1. Progress logging: Print metrics to stdout so they appear in the run log:

``python print(f"Epoch {epoch}/{num_epochs} | Loss: {loss:.4f} | Acc: {acc:.4f}") ``

1. Modal decorator (for cloud execution):

```python import modal app = modal.App("rstack-experiment")

@app.function(gpu="A100", timeout=600) def train(): # ... training code ... ```

1. requirements.txt: Include only what's needed. Always include:

`` torch numpy matplotlib datasets # if using HuggingFace ``

---

Step 4: Local Dry-Run

Before spending cloud GPU money, test locally:

rstack-preflight train.py

This runs train.py --smoke_test on CPU for 30 seconds. It catches:

• Import errors (missing packages)
• Data format issues
• Path bugs
• Syntax errors

If preflight fails:

• Show the error output
• Classify the error:
• ModuleNotFoundError → suggest adding to requirements.txt
• FileNotFoundError → check data paths
• SyntaxError → fix the generated code
• Fix the issue and re-run preflight
• Max 3 fix attempts before asking user for help

If preflight passes: Proceed to cloud submission.

---

Step 5: Human Confirmation

Use AskUserQuestion:

> Project: {project name}, branch: {branch} > > Code generated and preflight passed. Ready to submit to Modal. > GPU: A100 | Estimated duration: ~{X} minutes | Estimated cost: ~${Y} > > RECOMMENDATION: Submit to Modal.

Options:

• A) Submit to Modal
• B) Modify code first — I want to change something
• C) Run locally instead (requires local GPU)
• D) Skip — don't run this experiment

If the user has previously said "auto" or is in --auto mode, skip this confirmation.

---

Step 6: Cloud Execution

Run the experiment on Modal. Claude runs the command directly (same as GStack runs git push):

_PROJECT_ROOT=$(git rev-parse --show-toplevel 2>/dev/null || pwd)
# Determine run ID
RUN_NUM=0
[ -f "$_PROJECT_ROOT/.rstack/experiments.jsonl" ] && RUN_NUM=$(wc -l &1 | tee "$_PROJECT_ROOT/results/$RUN_ID/stdout.log"

After completion, download artifacts from Modal to results/$RUN_ID/.

Error handling (from Ignis run-experiment.ts classifyError):

If the run fails, read stderr and classify:

• If stderr contains ModuleNotFoundError: Import error. Suggest adding the package to requirements.txt. This is retryable.
• If stderr contains OutOfMemoryError or CUDA out of memory: Memory error. Suggest reducing batch_size or model size. This is retryable.
• If stderr contains FileNotFoundError: Data path error. Check that the dataset downloaded correctly and paths are right. This is retryable.
• If the process was killed by timeout: Training took too long. Suggest reducing epochs, dataset size, or model size. This is retryable.
• For any other non-zero exit: Show the last 50 lines of output. Ask user for guidance.

Max 3 retry attempts per experiment. After each failure, fix the identified issue before retrying.

---

Step 7: Log Results

Extract metrics from the run output and results/$RUN_ID/metrics.json.

Append a record to .rstack/experiments.jsonl:

{"v":1,"id":"run-001","ts":"2026-03-31T15:00:00Z","hypothesis":"Adding RMSNorm before attention improves convergence","metric_name":"val_loss","metric_value":0.342,"metric_improved":true,"status":"completed","cloud_provider":"modal","duration_s":312,"error_message":null,"artifacts":["results/run-001/metrics.json","results/run-001/figures/loss_curve.png"]}

Run ID format: run-{NNN} where NNN is the line count of experiments.jsonl + 1, zero-padded to 3 digits.

Status values: completed, failed, reverted

For failed runs: Still log them with status: "failed" and the error message. Every run gets logged.

---

Step 8: Assess and Iterate

Compare this run's metric against the previous best (if any prior runs exist).

Assessment (from AutoResearch program.md pattern):

• If improved: "Run {id} improved {metric} from {old} to {new} ({improvement}%). The modification worked."
• If worse or equal: "Run {id} did not improve. {metric} went from {old} to {new}. Consider reverting this change."
• Simplicity criterion: A tiny improvement ( Experiment progress: {N} runs complete.

> Best result: {metricname} = {bestvalue} (run-{best_id}) > Trend: {improving / plateauing / degrading} > > A) Continue experimenting — try next hypothesis > B) Change direction — different approach > C) Revise hypothesis — go back to /novelty-check > D) Stop — results are good enough for the paper

If A: suggest the next experiment modification based on what's been tried and what worked. Go back to Step 3. If B: ask what new direction, update experiment-plan.md, go back to Step 2. If C: go back to /novelty-check. If D: proceed. Suggest running /analyze-results next.

---

Step 9: Loop

If the user wants to continue, generate a new hypothesis based on:

1. What has been tried (read experiments.jsonl)
2. What worked vs what didn't
3. The original research idea and plan

Then go back to Step 3 with the new hypothesis. Each iteration should try something meaningfully different, not just random hyperparameter tweaks.

---

Important Rules

• NEVER run cloud experiments without human confirmation (unless in --auto mode).
• NEVER skip the preflight dry-run. It catches 80% of bugs for free.
• ALWAYS log every run to experiments.jsonl, even failures. The log IS the lab notebook.
• ALL generated code must write to /output/. This is the artifact contract.
• If Modal auth expires mid-session, tell user to run ! modal token new.
• Be honest about results. If the experiment didn't improve, say so clearly.
• Don't chase noise. Small random fluctuations are not improvements. With a single seed, be cautious about claiming improvements smaller than 2-3%.

---

Standalone Mode

If /experiment is invoked without prior /lit-review or /novelty-check:

• Ask user for the research goal directly
• Skip reading refined-idea.md (won't exist)
• Proceed from Step 2 (experiment planning)
• Note: "Running without literature review. Consider /lit-review first for better experiment design."

---

Telemetry (run last)

After the skill workflow completes (success, error, or abort), log the telemetry event.

# --- GENERATED EPILOGUE START ---
_TEL_END=$(date +%s)
_TEL_DUR=$(( _TEL_END - _TEL_START ))
rm -f ~/.rstack/analytics/.pending-"$_SESSION_ID" 2>/dev/null || true
if [ "$_TEL" != "off" ]; then
  echo '{"skill":"experiment","duration_s":"'"$_TEL_DUR"'","outcome":"OUTCOME","session":"'"$_SESSION_ID"'","ts":"'$(date -u +%Y-%m-%dT%H:%M:%SZ)'"}' >> ~/.rstack/analytics/skill-usage.jsonl 2>/dev/null || true
fi
if [ "$_TEL" != "off" ] && [ -x "$_RSTACK_DIR/bin/rstack-telemetry-log" ]; then
  "$_RSTACK_DIR/bin/rstack-telemetry-log" \
    --skill "experiment" --duration "$_TEL_DUR" --outcome "OUTCOME" \
    --session-id "$_SESSION_ID" --pipeline-stage "experiment" --compute-provider "$_COMPUTE" --gpu-type "$(_RSTACK_CONFIG get modal_default_gpu 2>/dev/null || echo A100)" 2>/dev/null &
fi
# --- GENERATED EPILOGUE END ---

Replace OUTCOME with success/error/abort based on the workflow result.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: sunnnybala
• Source: sunnnybala/Rstack
• License: MIT

Install and usage instructions live in the source repository linked above.