<purpose>
Spike an idea through experiential exploration — build focused experiments to feel the pieces
of a future app, validate feasibility, and produce verified knowledge for the real build.
Saves artifacts to `.planning/spikes/`. Companion to `/gsd-spike-wrap-up`.

Supports two modes:
- **Idea mode** (default) — user describes an idea to spike
- **Frontier mode** — no argument or "frontier" / "what should I spike?" — analyzes existing spike landscape and proposes integration and frontier spikes
</purpose>

<required_reading>
Read all files referenced by the invoking prompt's execution_context before starting.
</required_reading>

<process>

<step name="banner">
```
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 GSD ► SPIKING
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
```

Parse `$ARGUMENTS` for:
- `--quick` flag → set `QUICK_MODE=true`
- `--text` flag → set `TEXT_MODE=true`
- `frontier` or empty → set `FRONTIER_MODE=true`
- Remaining text → the idea to spike

**Text mode:** If TEXT_MODE is enabled, replace AskUserQuestion calls with plain-text numbered lists.
</step>

<step name="route">
## Routing

- **FRONTIER_MODE is true** → Jump to `frontier_mode`
- **Otherwise** → Continue to `setup_directory`
</step>

<step name="frontier_mode">
## Frontier Mode — Propose What to Spike Next

### Load the Spike Landscape

If no `.planning/spikes/` directory exists, tell the user there's nothing to analyze and offer to start fresh with an idea instead.

Otherwise, load in this order:

**a. MANIFEST.md** — the overall idea, requirements, and spike table with verdicts.

**b. Findings skills** — glob `./.claude/skills/spike-findings-*/SKILL.md` and read any that exist, plus their `references/*.md`. These contain curated knowledge from prior wrap-ups.

**c. CONVENTIONS.md** — read `.planning/spikes/CONVENTIONS.md` if it exists. Established stack and patterns.

**d. All spike READMEs** — read `.planning/spikes/*/README.md` for verdicts, results, investigation trails, and tags.

### Analyze for Integration Spikes

Review every pair and cluster of VALIDATED spikes. Look for:

- **Shared resources:** Two spikes that both touch the same API, database, state, or data format but were tested independently.
- **Data handoffs:** Spike A produces output that Spike B consumes. The formats were assumed compatible but never proven.
- **Timing/ordering:** Spikes that work in isolation but have sequencing dependencies in the real flow.
- **Resource contention:** Spikes that individually work but may compete for connections, memory, rate limits, or tokens when combined.

If integration risks exist, present them as concrete proposed spikes with names and Given/When/Then validation questions. If no meaningful integration risks exist, say so and skip this category.

### Analyze for Frontier Spikes

Think laterally about the overall idea from MANIFEST.md and what's been proven so far. Consider:

- **Gaps in the vision:** Capabilities assumed but unproven.
- **Discovered dependencies:** Findings that reveal new questions.
- **Alternative approaches:** Different angles for PARTIAL or INVALIDATED spikes.
- **Adjacent capabilities:** Things that would meaningfully improve the idea if feasible.
- **Comparison opportunities:** Approaches that worked but felt heavy.

Present frontier spikes as concrete proposals numbered from the highest existing spike number with Given/When/Then and risk ordering.

### Get Alignment and Execute

Present all integration and frontier candidates, then ask which to run. When the user picks spikes, write definitions into `.planning/spikes/MANIFEST.md` (appending to existing table) and proceed directly to building them starting at `research`.
</step>

<step name="setup_directory">
Create `.planning/spikes/` if it doesn't exist:

```bash
mkdir -p .planning/spikes
```

Check for existing spikes to determine numbering:
```bash
ls -d .planning/spikes/[0-9][0-9][0-9]-* 2>/dev/null | sort | tail -1
```

Check `commit_docs` config:
```bash
COMMIT_DOCS=$(gsd-sdk query config-get commit_docs 2>/dev/null || echo "true")
```
</step>

<step name="detect_stack">
Check for the project's tech stack to inform spike technology choices.

**Check conventions first.** If `.planning/spikes/CONVENTIONS.md` exists, follow its stack and patterns — these represent validated choices the user expects to see continued.

**Then check the project stack:**
```bash
ls package.json pyproject.toml Cargo.toml go.mod 2>/dev/null
```

Use the project's language/framework by default. For greenfield projects with no conventions and no existing stack, pick whatever gets to a runnable result fastest.

Avoid unless the spike specifically requires it:
- Complex package management beyond `npm install` or `pip install`
- Build tools, bundlers, or transpilers
- Docker, containers, or infrastructure
- Env files or config systems — hardcode everything
</step>

<step name="load_prior_context">
If `.planning/spikes/` has existing content, load context in this priority order:

**a. Conventions:** Read `.planning/spikes/CONVENTIONS.md` if it exists.

**b. Findings skills:** Glob for `./.claude/skills/spike-findings-*/SKILL.md` and read any that exist, plus their `references/*.md` files.

**c. Manifest:** Read `.planning/spikes/MANIFEST.md` for the index of all spikes.

**d. Related READMEs:** Based on the new idea, identify which prior spikes are related by matching tags, names, technologies, or domain overlap. Read only those `.planning/spikes/*/README.md` files. Skip unrelated ones.

Cross-reference against this full body of prior work:
- **Skip already-validated questions.** Note the prior spike number and move on.
- **Build on prior findings.** Don't repeat failed approaches. Use their Research and Results sections.
- **Reuse prior research.** Carry findings forward rather than re-researching.
- **Follow established conventions.** Mention any deviation.
- **Call out relevant prior art** when presenting the decomposition.

If no `.planning/spikes/` exists, skip this step.
</step>

<step name="decompose">
**If `QUICK_MODE` is true:** Skip decomposition and alignment. Take the user's idea as a single spike question. Assign it the next available number. Jump to `research`.

Break the idea into 2-5 independent questions. Frame each as Given/When/Then. Present as a table:

```
| # | Spike | Type | Validates (Given/When/Then) | Risk |
|---|-------|------|-----------------------------|------|
| 001 | websocket-streaming | standard | Given a WS connection, when LLM streams tokens, then client receives chunks < 100ms | **High** |
| 002a | pdf-parse-pdfjs | comparison | Given a multi-page PDF, when parsed with pdfjs, then structured text is extractable | Medium |
| 002b | pdf-parse-camelot | comparison | Given a multi-page PDF, when parsed with camelot, then structured text is extractable | Medium |
```

**Spike types:**
- **standard** — one approach answering one question
- **comparison** — same question, different approaches. Shared number with letter suffix.

Good spikes: specific feasibility questions with observable output.
Bad spikes: too broad, no observable output, or just reading/planning.

Order by risk — most likely to kill the idea runs first.
</step>

<step name="align">
**If `QUICK_MODE` is true:** Skip.

╔══════════════════════════════════════════════════════════════╗
║  CHECKPOINT: Decision Required                               ║
╚══════════════════════════════════════════════════════════════╝

{spike table from decompose step}

──────────────────────────────────────────────────────────────
→ Build all in this order, or adjust the list?
──────────────────────────────────────────────────────────────
</step>

<step name="research">
## Research and Briefing Before Each Spike

This step runs **before each individual spike**, not once at the start.

**a. Present a spike briefing:**

> **Spike NNN: Descriptive Name**
> [2-3 sentences: what this spike is, why it matters, key risk or unknown.]

**b. Research the current state of the art.** Use context7 (resolve-library-id → query-docs) for libraries/frameworks. Use web search for APIs/services without a context7 entry. Read actual documentation.

**c. Surface competing approaches** as a table:

| Approach | Tool/Library | Pros | Cons | Status |
|----------|-------------|------|------|--------|
| ... | ... | ... | ... | ... |

**Chosen approach:** [which one and why]

If 2+ credible approaches exist, plan to build quick variants within the spike and compare them.

**d. Capture research findings** in a `## Research` section in the README.

**Skip when unnecessary** for pure logic with no external dependencies.
</step>

<step name="create_manifest">
Create or update `.planning/spikes/MANIFEST.md`:

```markdown
# Spike Manifest

## Idea
[One paragraph describing the overall idea being explored]

## Requirements
[Design decisions that emerged from the user's choices during spiking. Non-negotiable for the real build. Updated as spikes progress.]

- [e.g., "Must use streaming JSON output, not single-response"]
- [e.g., "Must support reconnection on network failure"]

## Spikes

| # | Name | Type | Validates | Verdict | Tags |
|---|------|------|-----------|---------|------|
```

**Track requirements as they emerge.** When the user expresses a preference during spiking, add it to the Requirements section immediately.
</step>

<step name="reground">
## Re-Ground Before Each Spike

Before starting each spike (not just the first), re-read `.planning/spikes/MANIFEST.md` and `.planning/spikes/CONVENTIONS.md` to prevent drift within long sessions. Check the Requirements section — make sure the spike doesn't contradict any established requirements.
</step>

<step name="build_spikes">
## Build Each Spike Sequentially

**Depth over speed.** The goal is genuine understanding, not a quick verdict. Never declare VALIDATED after a single happy-path test. Follow surprising findings. Test edge cases. Document the investigation trail, not just the conclusion.

**Comparison spikes** use shared number with letter suffix: `NNN-a-name` / `NNN-b-name`. Build back-to-back, then head-to-head comparison.

### For Each Spike:

**a.** Create `.planning/spikes/NNN-descriptive-name/`

**b.** Assess whether the user needs to experience this spike or Claude can verify alone:

Build interactive prototype when validating:
- Behavior that unfolds over time (streaming, real-time, animations)
- Cause-and-effect sequences (click X → Y happens)
- Data flow between systems
- Visual or presentation quality
- Timing or performance feel

Stay with stdout/CLI when validating:
- Pure data transformation
- Binary yes/no questions
- Benchmark numbers
- Facts, not feelings

**If the spike needs runtime observability,** build a forensic log layer:
1. Event log array with ISO timestamps and category tags
2. Export mechanism (server: GET endpoint, CLI: JSON file, browser: Export button)
3. Log summary (event counts, duration, errors, metadata)
4. Analysis helpers if volume warrants it

**c.** Build the code. Start with simplest version, then deepen.

**d.** Iterate when findings warrant it:
- **Surprising surface?** Write a follow-up test that isolates and explores it.
- **Answer feels shallow?** Probe edge cases — large inputs, concurrent requests, malformed data, network failures.
- **Assumption wrong?** Adjust. Note the pivot in the README.

Multiple files per spike are expected for complex questions (e.g., `test-basic.js`, `test-edge-cases.js`, `benchmark.js`).

**e.** Write `README.md` with YAML frontmatter:

```markdown
---
spike: NNN
name: descriptive-name
type: standard
validates: "Given [precondition], when [action], then [expected outcome]"
verdict: PENDING
related: []
tags: [tag1, tag2]
---

# Spike NNN: Descriptive Name

## What This Validates
[Given/When/Then]

## Research
[Docs checked, approach comparison table, chosen approach, gotchas. Omit if no external deps.]

## How to Run
[Command(s)]

## What to Expect
[Concrete observable outcomes]

## Observability
[If forensic log layer exists. Omit otherwise.]

## Investigation Trail
[Updated as spike progresses. Document each iteration: what tried, what revealed, what tried next.]

## Results
[Verdict, evidence, surprises, log analysis findings.]
```

**f.** Auto-link related spikes silently.

**g.** Run and verify:
- Self-verifiable: run, iterate if findings warrant deeper investigation, update verdict
- Needs human judgment: present checkpoint box:

╔══════════════════════════════════════════════════════════════╗
║  CHECKPOINT: Verification Required                           ║
╚══════════════════════════════════════════════════════════════╝

**Spike {NNN}: {name}**
**How to run:** {command}
**What to expect:** {concrete outcomes}

──────────────────────────────────────────────────────────────
→ Does this match what you expected? Describe what you see.
──────────────────────────────────────────────────────────────

**h.** Update `.planning/spikes/MANIFEST.md` with the spike's row.

**i.** Commit (if `COMMIT_DOCS` is true):
```bash
gsd-sdk query commit "docs(spike-NNN): [VERDICT] — [key finding]" .planning/spikes/NNN-descriptive-name/ .planning/spikes/MANIFEST.md
```

**j.** Report:
```
◆ Spike NNN: {name}
  Verdict: {VALIDATED ✓ / INVALIDATED ✗ / PARTIAL ⚠}
  Key findings: {not just verdict — investigation trail, surprises, edge cases explored}
  Impact: {effect on remaining spikes}
```

Do not rush to a verdict. A spike that says "VALIDATED — it works" with no nuance is almost always incomplete.

**k.** If core assumption invalidated:

╔══════════════════════════════════════════════════════════════╗
║  CHECKPOINT: Decision Required                               ║
╚══════════════════════════════════════════════════════════════╝

Core assumption invalidated by Spike {NNN}.
{what was invalidated and why}

──────────────────────────────────────────────────────────────
→ Continue with remaining spikes / Pivot approach / Abandon
──────────────────────────────────────────────────────────────
</step>

<step name="update_conventions">
## Update Conventions

After all spikes in this session are built, update `.planning/spikes/CONVENTIONS.md` with patterns that emerged or solidified.

```markdown
# Spike Conventions

Patterns and stack choices established across spike sessions. New spikes follow these unless the question requires otherwise.

## Stack
[What we use for frontend, backend, scripts, and why]

## Structure
[Common file layouts, port assignments, naming patterns]

## Patterns
[Recurring approaches: how we handle auth, how we style, how we serve]

## Tools & Libraries
[Preferred packages with versions that worked, and any to avoid]
```

Only include patterns that repeated across 2+ spikes or were explicitly chosen by the user. If `CONVENTIONS.md` already exists, update sections with new patterns from this session.

Commit (if `COMMIT_DOCS` is true):
```bash
gsd-sdk query commit "docs(spikes): update conventions" .planning/spikes/CONVENTIONS.md
```
</step>

<step name="report">
```
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 GSD ► SPIKE COMPLETE ✓
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

## Verdicts

| # | Name | Type | Verdict |
|---|------|------|---------|
| 001 | {name} | standard | ✓ VALIDATED |
| 002a | {name} | comparison | ✓ WINNER |

## Key Discoveries
{surprises, gotchas, investigation trail highlights}

## Feasibility Assessment
{overall viability}

## Signal for the Build
{what to use, avoid, watch out for}
```

───────────────────────────────────────────────────────────────

## ▶ Next Up

**Package findings** — wrap spike knowledge into an implementation blueprint

`/gsd-spike-wrap-up`

───────────────────────────────────────────────────────────────

**Also available:**
- `/gsd-spike` — spike more ideas (or run with no argument for frontier mode)
- `/gsd-plan-phase` — start planning the real implementation
- `/gsd-explore` — continue exploring the idea

───────────────────────────────────────────────────────────────
</step>

</process>

<success_criteria>
- [ ] `.planning/spikes/` created (auto-creates if needed, no project init required)
- [ ] Prior spikes and findings skills consulted before building
- [ ] Conventions followed (or deviation documented)
- [ ] Research grounded each spike in current docs before coding
- [ ] Depth over speed — edge cases tested, surprising findings followed, investigation trail documented
- [ ] Comparison spikes built back-to-back with head-to-head verdict
- [ ] Spikes needing human interaction have forensic log layer
- [ ] Requirements tracked in MANIFEST.md as they emerge from user choices
- [ ] CONVENTIONS.md created or updated with patterns that emerged
- [ ] Each spike README has complete frontmatter, Investigation Trail, and Results
- [ ] MANIFEST.md is current (with Type column and Requirements section)
- [ ] Commits use `docs(spike-NNN): [VERDICT]` format
- [ ] Consolidated report presented with next-step routing
</success_criteria>
