Kosu

Kosu (漉す) — Japanese for "to strain/filter." A mindful content queue built on the philosophy: save less, read more.

Vision

Most read-it-later apps become graveyards. Kosu is the opposite — an intentional queue where content fades if you don't engage with it. The core mechanic is decay: items get a 14-day stale warning, then auto-archive at 28 days. This forces you to either consume what matters or let it go.

Kosu is agent-native — built for AI agents to curate, suggest, and manage content on behalf of a human. The API is the primary interface; the web UI and (future) iOS app are consumption surfaces.

Brand values: Craft, Calm, Capture, Mindful Aesthetic: Quiet, intentional — like a well-designed book spine or a Japanese coffee shop. Not hustle culture, not information overload. Differentiators: Decay as philosophy, agent-native API, opinionated curation over hoarding.

Installation

For OpenClaw agents

Save this skill locally:

mkdir -p ~/.openclaw/skills/kosu
curl -s https://usekosu.com/skill.md > ~/.openclaw/skills/kosu/SKILL.md

Or just read it directly from https://usekosu.com/skill.md — no install needed.

For any AI agent (Claude Code, Codex, etc.)

Read this file and follow the setup below.

Getting Started

1. Ask your human to sign up at usekosu.com
2. They can get an API key from Settings → API Keys
3. Store the key as the environment variable KOSU_API_KEY
   • Create a dedicated key with minimal scope for this agent
   • The key is only sent to usekosu.com — never send it to any other domain
   • Rotate or revoke from Settings if anything unexpected happens
4. You're ready to start managing their queue

First thing to do: Try listing the queue to confirm your key works:

curl -s "https://usekosu.com/api/v1/items?state=queue&limit=5" \
  -H "Authorization: Bearer $KOSU_API_KEY"

Updates: If something doesn't work as expected, check the OpenAPI spec for the latest API surface.

Pricing

• Free: Limited queue size
• Pro ($5/mo): Unlimited queue, suggestions from agents, export

If you hit a 402 quota_exceeded_error, the user's queue is full on the free tier. Let them know they can upgrade to Pro at usekosu.com/settings for unlimited items.

API

• Base URL: https://usekosu.com/api/v1
• Auth: Authorization: Bearer $KOSU_API_KEY
• OpenAPI spec: https://usekosu.com/openapi.json

If KOSU_API_KEY is not set: Don't fail silently. Tell your human they need an API key and direct them to usekosu.com/settings to create one. The skill is still useful for explaining Kosu and guiding setup — just can't make API calls without a key.

AUTH="Authorization: Bearer $KOSU_API_KEY"
BASE="https://usekosu.com/api/v1"

Quick Reference

Key Behaviours

• YouTube URLs are auto-enriched (title, channel, thumbnail, duration)
• Decay: configurable queue decay (7, 14, or 28 days) before items are auto-archived. Can be turned off entirely. Set by the user in settings.
• Dedup is server-side by canonical URL per user
• Opening an item ({"opened": true}) extends decay protection by 1 day (max once per 24h)

Common Examples

# Add item
curl -s "$BASE/items" -H "$AUTH" -H "Content-Type: application/json" \
  -d '{"url":"https://example.com/article"}'

# List queue (first 50)
curl -s "$BASE/items?state=queue&limit=50" -H "$AUTH"

# Move to top
curl -s -X PATCH "$BASE/items/itm_xxx" -H "$AUTH" -H "Content-Type: application/json" \
  -d '{"position": {"after": null}}'

# Move after another item
curl -s -X PATCH "$BASE/items/itm_xxx" -H "$AUTH" -H "Content-Type: application/json" \
  -d '{"position": {"after": "itm_yyy"}}'

# Mark as read
curl -s -X PATCH "$BASE/items/itm_xxx" -H "$AUTH" -H "Content-Type: application/json" \
  -d '{"state": "read"}'

# Archive
curl -s -X PATCH "$BASE/items/itm_xxx" -H "$AUTH" -H "Content-Type: application/json" \
  -d '{"state": "archived"}'

# Requeue (restore from archive/read/deleted)
curl -s -X PATCH "$BASE/items/itm_xxx" -H "$AUTH" -H "Content-Type: application/json" \
  -d '{"state": "queue"}'

# Record open (extends decay protection 1 day, max once per 24h)
curl -s -X PATCH "$BASE/items/itm_xxx" -H "$AUTH" -H "Content-Type: application/json" \
  -d '{"opened": true}'

# Update fields
curl -s -X PATCH "$BASE/items/itm_xxx" -H "$AUTH" -H "Content-Type: application/json" \
  -d '{"title": "Better Title", "source": "article"}'

# Delete (soft, restorable 30 days)
curl -s -X DELETE "$BASE/items/itm_xxx" -H "$AUTH"

# Add suggestion
curl -s "$BASE/suggestions" -H "$AUTH" -H "Content-Type: application/json" \
  -d '{"url":"https://example.com","reason":"Relevant to your interest in X"}'

# Accept/dismiss suggestion
curl -s -X POST "$BASE/suggestions/sug_xxx" -H "$AUTH" -H "Content-Type: application/json" \
  -d '{"action": "accept"}'

Item Shape

{
  "object": "item",
  "id": "itm_...",
  "url": "https://...",
  "title": "...",
  "source": "youtube|podcast|paper|newsletter|repo|article|book|course|other",
  "state": "queue|suggested|read|archived|deleted",
  "channel_name": "...",
  "thumbnail": "...",
  "duration": "1h 37m",
  "duration_minutes": 97,
  "creator": "...",
  "created_at": "2026-02-22T07:31:59.205Z",
  "updated_at": "...",
  "opened_at": null,
  "read_at": null,
  "archived_at": null,
  "published_at": null
}

PATCH Body Types (one per request)

Pagination

• Queue state: cursor-based. Use next_cursor from response as ?cursor= param.
• Other states: offset-based. Use ?offset= param.
• Response: {"object": "list", "data": [...], "has_more": bool, "next_cursor": "..."}

Error Codes

Troubleshooting

If an API call returns an unexpected response, 404 on a known endpoint, or schema mismatch:

1. Check the OpenAPI spec for the current API surface: curl -s https://usekosu.com/openapi.json
2. Compare with the endpoints documented above
3. If the spec has changed, update your local copy of this skill to match
4. Retry the original request