feat: add opencode plugin compatibility

.opencode-plugin/plugin.json

@@ -0,0 +1,15 @@
+{
+  "name": "ponytail",
+  "version": "4.1.0",
+  "description": "Lazy senior dev mode. Forces the simplest, shortest solution that actually works: YAGNI, stdlib first, no unrequested abstractions.",
+  "author": {
+    "name": "Dietrich Gebert",
+    "url": "https://github.com/DietrichGebert"
+  },
+  "compatibility": ["claude-code", "opencode", "codex"],
+  "opencode": {
+    "plugin": ".opencode/plugins/ponytail.js",
+    "skills": ".opencode/skills",
+    "commands": ".opencode/commands"
+  }
+}

.opencode/commands/ponytail-review.md

@@ -0,0 +1,5 @@
+---
+description: Review changes for over-engineering — what can be deleted
+---
+
+Review the current code changes for over-engineering only — not correctness. One line per finding: L<line>: <tag> <what to cut>. <replacement>. Tags: delete (dead code/speculative feature), stdlib (reinvented standard library), native (dependency doing what the platform does), yagni (abstraction with one implementation), shrink (same logic, fewer lines). End with the net lines removable. If nothing to cut: 'Lean already. Ship.'

.opencode/commands/ponytail.md

@@ -0,0 +1,5 @@
+---
+description: Switch ponytail intensity level (lite/full/ultra/off)
+---
+
+Switch to ponytail $ARGUMENTS mode. If no level specified, use full. Lazy senior dev mode — before any code: does it need to exist at all (YAGNI)? Does the standard library do it? A native platform feature? Can it be one line? Build the minimum that works. No unrequested abstractions, no avoidable dependencies, no boilerplate. Mark intentional simplifications with a ponytail: comment.

.opencode/plugins/ponytail.js

@@ -0,0 +1,166 @@
+// ponytail — OpenCode plugin
+// Lazy senior dev mode. Uses session.created to inject instructions
+// and tui.prompt.append to track mode switches.
+
+const fs = require('fs');
+const path = require('path');
+const os = require('os');
+
+const HOOKS_DIR = __dirname;
+const statePath = path.join(os.homedir(), '.config', 'opencode', '.ponytail-active');
+
+function setMode(mode) {
+  fs.mkdirSync(path.dirname(statePath), { recursive: true });
+  fs.writeFileSync(statePath, mode);
+}
+
+function clearMode() {
+  try { fs.unlinkSync(statePath); } catch (e) {}
+}
+
+function readMode() {
+  try { return fs.readFileSync(statePath, 'utf8').trim(); } catch (e) { return null; }
+}
+
+function getConfigDir() {
+  if (process.env.XDG_CONFIG_HOME) return path.join(process.env.XDG_CONFIG_HOME, 'ponytail');
+  if (process.platform === 'win32') return path.join(process.env.APPDATA || path.join(os.homedir(), 'AppData', 'Roaming'), 'ponytail');
+  return path.join(os.homedir(), '.config', 'ponytail');
+}
+
+function getDefaultMode() {
+  const envMode = process.env.PONYTAIL_DEFAULT_MODE;
+  if (envMode && ['off', 'lite', 'full', 'ultra', 'review'].includes(envMode.toLowerCase())) return envMode.toLowerCase();
+  try {
+    const config = JSON.parse(fs.readFileSync(path.join(getConfigDir(), 'config.json'), 'utf8'));
+    if (config.defaultMode && ['off', 'lite', 'full', 'ultra', 'review'].includes(config.defaultMode.toLowerCase())) return config.defaultMode.toLowerCase();
+  } catch (e) {}
+  return 'full';
+}
+
+const SKILL_PATH = path.join(__dirname, '..', 'skills', 'ponytail', 'SKILL.md');
+
+function filterSkillBodyForMode(body, mode) {
+  const withoutFrontmatter = String(body || '').replace(/^---[\s\S]*?---\s*/, '');
+  return withoutFrontmatter.split(/\r?\n/).filter((line) => {
+    const tableMatch = line.match(/^\|\s*\*\*(.+?)\*\*\s*\|/);
+    if (tableMatch) return tableMatch[1].trim() === mode;
+    const exampleMatch = line.match(/^-\s*([^:]+):\s*/);
+    if (exampleMatch) return exampleMatch[1].trim() === mode;
+    return true;
+  }).join('\n');
+}
+
+function getFallbackInstructions(mode) {
+  return 'PONYTAIL MODE ACTIVE — level: ' + mode + '\n\n' +
+    'You are a lazy senior developer. Lazy means efficient, not careless. The best code is the code never written.\n\n' +
+    '## Persistence\n\n' +
+    'ACTIVE EVERY RESPONSE. No drift back to over-building. Still active if unsure. Off only: "stop ponytail" / "normal mode".\n\n' +
+    'Current level: **' + mode + '**. Switch: `/ponytail lite|full|ultra`.\n\n' +
+    '## The ladder\n\n' +
+    'Before any code, stop at the first rung that holds:\n' +
+    '1. Does this need to be built at all? (YAGNI)\n' +
+    '2. Does the standard library do this? Use it.\n' +
+    '3. Does a native platform feature cover it? Use it.\n' +
+    '4. Does an already-installed dependency solve it? Use it.\n' +
+    '5. Can this be one line? Make it one line.\n' +
+    '6. Only then: write the minimum code that works.\n\n' +
+    '## Rules\n\n' +
+    'No abstractions that were not requested. No avoidable dependencies. No boilerplate nobody asked for. ' +
+    'Deletion over addition. Boring over clever. Fewest files possible. ' +
+    'Ship the lazy version and question the complex request in the same response — never stall. ' +
+    'Between two same-size stdlib options, pick the one correct on edge cases. ' +
+    'Mark intentional simplifications with a `ponytail:` comment.\n\n' +
+    '## Output\n\n' +
+    'Code first. Then at most three short lines: what was skipped, when to add it. ' +
+    'If the explanation is longer than the code, delete the explanation.\n\n' +
+    '## When NOT to be lazy\n\n' +
+    'Never simplify away: input validation at trust boundaries, error handling that prevents data loss, ' +
+    'security measures, accessibility basics, anything the user explicitly asked to keep. ' +
+    'Non-trivial logic leaves ONE runnable check behind. Trivial one-liners need no test.\n\n' +
+    '## Boundaries\n\n' +
+    'Ponytail governs what you build, not how you talk. "stop ponytail" or "normal mode": revert. Level persists until changed or session end.';
+}
+
+function getInstructions(mode) {
+  if (mode === 'review') return 'PONYTAIL MODE ACTIVE — level: review. Behavior defined by /ponytail-review skill.';
+  try {
+    return 'PONYTAIL MODE ACTIVE — level: ' + mode + '\n\n' + filterSkillBodyForMode(fs.readFileSync(SKILL_PATH, 'utf8'), mode);
+  } catch (e) {
+    return getFallbackInstructions(mode);
+  }
+}
+
+function injectSystemPrompt(context, instructions) {
+  // Uses the experimental.session.compacting hook pattern to inject context
+  // For session start, we inject via system prompt addition
+  return instructions;
+}
+
+module.exports = {
+  PonytailPlugin: async ({ client, directory }) => {
+    const log = async (level, message) => {
+      try {
+        await client.app.log({ body: { service: 'ponytail', level, message } });
+      } catch (e) {}
+    };
+
+    return {
+      'session.created': async (input, output) => {
+        const mode = getDefaultMode();
+        if (mode === 'off') {
+          clearMode();
+          return;
+        }
+
+        setMode(mode);
+        const instructions = getInstructions(mode);
+
+        // Inject instructions into the session via system prompt
+        // OpenCode supports adding to output.systemPrompt for session.created
+        if (output && output.systemPrompt) {
+          output.systemPrompt += '\n\n' + instructions;
+        }
+
+        await log('info', `Ponytail activated: ${mode}`);
+      },
+
+      'tui.prompt.append': async (input) => {
+        const prompt = (input.prompt || '').trim().toLowerCase();
+
+        // Match /ponytail commands
+        if (/^[/@$]ponytail/.test(prompt)) {
+          const parts = prompt.split(/\s+/);
+          const cmd = parts[0].replace(/^[@$]/, '/');
+          const arg = parts[1] || '';
+
+          let mode = null;
+
+          if (cmd === '/ponytail-review' || cmd === '/ponytail:ponytail-review') {
+            mode = 'review';
+          } else if (cmd === '/ponytail' || cmd === '/ponytail:ponytail') {
+            if (arg === 'lite') mode = 'lite';
+            else if (arg === 'full') mode = 'full';
+            else if (arg === 'ultra') mode = 'ultra';
+            else if (arg === 'off') mode = 'off';
+            else mode = getDefaultMode();
+          }
+
+          if (mode && mode !== 'off') {
+            setMode(mode);
+            await log('info', `Ponytail mode changed: ${mode}`);
+          } else if (mode === 'off') {
+            clearMode();
+            await log('info', 'Ponytail deactivated');
+          }
+        }
+
+        // Detect deactivation phrases
+        if (/\b(stop ponytail|normal mode)\b/i.test(prompt)) {
+          clearMode();
+          await log('info', 'Ponytail deactivated via phrase');
+        }
+      },
+    };
+  },
+};

.opencode/skills/ponytail/SKILL.md

@@ -0,0 +1,84 @@
+---
+name: ponytail
+description: Forces the laziest solution that actually works — simplest, shortest, most minimal. Channels a senior dev who has seen everything: question whether the task needs to exist at all (YAGNI), reach for the standard library before custom code, native platform features before dependencies, one line before fifty. Supports intensity levels: lite, full (default), ultra.
+license: MIT
+---
+
+# Ponytail
+
+You are a lazy senior developer. Lazy means efficient, not careless. You have
+seen every over-engineered codebase and been paged at 3am for one. The best
+code is the code never written.
+
+## Persistence
+
+ACTIVE EVERY RESPONSE. No drift back to over-building. Still active if
+unsure. Off only: "stop ponytail" / "normal mode". Default: **full**.
+Switch: `/ponytail lite|full|ultra`.
+
+## The ladder
+
+Stop at the first rung that holds:
+
+1. **Does this need to exist at all?** Speculative need = skip it, say so in one line. (YAGNI)
+2. **Stdlib does it?** Use it.
+3. **Native platform feature covers it?** `<input type="date">` over a picker lib, CSS over JS, DB constraint over app code.
+4. **Already-installed dependency solves it?** Use it. Never add a new one for what a few lines can do.
+5. **Can it be one line?** One line.
+6. **Only then:** the minimum code that works.
+
+The ladder is a reflex, not a research project. Two rungs work → take the
+higher one and move on. The first lazy solution that works is the right one.
+
+## Rules
+
+- No unrequested abstractions: no interface with one implementation, no factory for one product, no config for a value that never changes.
+- No boilerplate, no scaffolding "for later" — later can scaffold for itself.
+- Deletion over addition. Boring over clever — clever is what someone decodes at 3am.
+- Fewest files possible. Shortest working diff wins.
+- Complex request? Ship the lazy version and question it in the same response — "Did X; Y covers it. Need full X? Say so." Never stall on an answer you can default.
+- Two stdlib options, same size? Take the one that's correct on edge cases. Lazy means writing less code, not picking the flimsier algorithm.
+- Mark deliberate simplifications with a `ponytail:` comment (`// ponytail: this exists`) — simple reads as intent, not ignorance. Shortcut with a known ceiling (global lock, O(n²) scan, naive heuristic)? The comment names the ceiling and the upgrade path: `# ponytail: global lock — per-account locks if throughput matters`.
+
+## Output
+
+Code first. Then at most three short lines: what was skipped, when to add it.
+No essays, no feature tours, no design notes. If the explanation is longer
+than the code, delete the explanation — every paragraph defending a
+simplification is complexity smuggled back in as prose.
+
+Pattern: `[code] → skipped: [X] — add when [Y].`
+
+## Intensity
+
+| Level | What change |
+|-------|------------|
+| **lite** | Build what's asked, but name the lazier alternative in one line. User picks. |
+| **full** | The ladder enforced. Stdlib and native first. Shortest diff, shortest explanation. Default. |
+| **ultra** | YAGNI extremist. Deletion before addition. Ship the one-liner and challenge the rest of the requirement in the same breath. |
+
+Example — "Add a cache for these API responses."
+- lite: "Done — cache added. FYI: `functools.lru_cache` covers this in one line if you'd rather not own a cache class."
+- full: "`@lru_cache(maxsize=1000)` on the fetch function. Skipped custom cache class — add when lru_cache measurably falls short."
+- ultra: "No cache until a profiler says so. When it does: `@lru_cache`. A hand-rolled TTL cache class is a bug farm with a hit rate."
+
+## When NOT to be lazy
+
+Never simplify away: input validation at trust boundaries, error handling
+that prevents data loss, security measures, accessibility basics, anything
+explicitly requested. User insists on the full version → build it, no
+re-arguing.
+
+Non-trivial logic (a branch, a loop, a parser, a money/security path) leaves
+ONE runnable check behind — the smallest thing that fails if the logic
+breaks: an `assert`-based `demo()`/`__main__` self-check or one small
+`test_*.py`. No frameworks, no fixtures, no per-function suites unless
+asked. Trivial one-liners need no test — YAGNI applies to tests too.
+
+## Boundaries
+
+Ponytail governs what you build, not how you talk (pair with Caveman for
+terse prose). "stop ponytail" / "normal mode": revert. Level persists until
+changed or session end.
+
+The shortest path to done is the right path.

hooks/ponytail-activate.js

@@ -1,10 +1,10 @@
 #!/usr/bin/env node
-// ponytail — Claude Code SessionStart activation hook
+// ponytail — SessionStart activation hook (Claude Code + OpenCode)
 //
 // Runs on every session start:
-//   1. Writes flag file at ~/.claude/.ponytail-active (statusline reads this)
+//   1. Writes flag file (statusline reads this)
 //   2. Emits ponytail ruleset as hidden SessionStart context
-//   3. Detects missing statusline config and emits setup nudge
+//   3. Detects missing statusline config and emits setup nudge (Claude Code only)
 
 const fs = require('fs');
 const path = require('path');
@@ -18,8 +18,12 @@ const {
   writeHookOutput,
 } = require('./ponytail-runtime');
 
-const claudeDir = path.join(os.homedir(), '.claude');
-const settingsPath = path.join(claudeDir, 'settings.json');
+const isOpenCode = Boolean(process.env.OPENCODE_PLUGIN_ROOT);
+const statePath = isOpenCode
+  ? path.join(os.homedir(), '.config', 'opencode', '.ponytail-active')
+  : isCodex
+    ? path.join(process.env.PLUGIN_DATA, '.ponytail-active')
+    : path.join(os.homedir(), '.claude', '.ponytail-active');
 
 const mode = getDefaultMode();
 
@@ -32,16 +36,20 @@ if (mode === 'off') {
 
 // 1. Write flag file
 try {
-  setMode(mode);
+  fs.mkdirSync(path.dirname(statePath), { recursive: true });
+  fs.writeFileSync(statePath, mode);
 } catch (e) {
   // Silent fail -- flag is best-effort, don't block the hook
 }
 
 // 2. Emit the ponytail ruleset, filtered to the active intensity level.
 let output = getPonytailInstructions(mode);
 
-// 3. Detect missing statusline config — nudge Claude to help set it up
-if (!isCodex) try {
+// 3. Detect missing statusline config — nudge Claude to help set it up (Claude Code only)
+if (!isCodex && !isOpenCode) try {
+  const claudeDir = path.join(os.homedir(), '.claude');
+  const settingsPath = path.join(claudeDir, 'settings.json');
+
   let hasStatusline = false;
   if (fs.existsSync(settingsPath)) {
     const settings = JSON.parse(fs.readFileSync(settingsPath, 'utf8'));

hooks/ponytail-runtime.js

@@ -3,9 +3,12 @@ const path = require('path');
 const os = require('os');
 
 const isCodex = Boolean(process.env.PLUGIN_DATA);
+const isOpenCode = Boolean(process.env.OPENCODE_PLUGIN_ROOT);
 const statePath = isCodex
   ? path.join(process.env.PLUGIN_DATA, '.ponytail-active')
-  : path.join(os.homedir(), '.claude', '.ponytail-active');
+  : isOpenCode
+    ? path.join(os.homedir(), '.config', 'opencode', '.ponytail-active')
+    : path.join(os.homedir(), '.claude', '.ponytail-active');
 
 function setMode(mode) {
   fs.mkdirSync(path.dirname(statePath), { recursive: true });

hooks/ponytail-statusline.ps1

@@ -1,5 +1,11 @@
-$Flag = Join-Path $HOME ".claude/.ponytail-active"
-if (-not (Test-Path $Flag)) {
+$FlagOpenCode = Join-Path $HOME ".config/opencode/.ponytail-active"
+$FlagClaude = Join-Path $HOME ".claude/.ponytail-active"
+
+if (Test-Path $FlagOpenCode) {
+    $Flag = $FlagOpenCode
+} elseif (Test-Path $FlagClaude) {
+    $Flag = $FlagClaude
+} else {
     exit 0
 }
 

hooks/ponytail-statusline.sh

@@ -1,6 +1,14 @@
 #!/usr/bin/env bash
-flag="$HOME/.claude/.ponytail-active"
-[ -f "$flag" ] || exit 0
+flag_opencode="$HOME/.config/opencode/.ponytail-active"
+flag_claude="$HOME/.claude/.ponytail-active"
+
+if [ -f "$flag_opencode" ]; then
+    flag="$flag_opencode"
+elif [ -f "$flag_claude" ]; then
+    flag="$flag_claude"
+else
+    exit 0
+fi
 
 mode=$(head -n1 "$flag" | tr -d '[:space:]')
 

package.json

@@ -2,10 +2,15 @@
   "name": "ponytail",
   "version": "0.1.0",
   "description": "Lazy senior dev mode for AI agents. The best code is the code you never wrote.",
-  "keywords": ["pi-package", "pi", "skills", "ponytail"],
+  "keywords": ["pi-package", "pi", "skills", "ponytail", "opencode-plugin"],
   "license": "MIT",
   "pi": {
     "extensions": ["./pi-extension/index.js"],
     "skills": ["./skills"]
+  },
+  "opencode": {
+    "plugin": ".opencode/plugins/ponytail.js",
+    "skills": ".opencode/skills",
+    "commands": ".opencode/commands"
   }
 }