Skills

state-db

Installation
SKILL.md

State DB

Centralized state management for Claude Code skills via PostgREST REST API.

Setup

All operations use these shell variables. Define them before executing any command:

DB_URL="$STATE_DB_POSTGREST_URL/skill_state"
DB_ROLE="${STATE_DB_POSTGREST_ROLE:-web_anon}"
DB_TOKEN=$(python3 -c "
import hmac,hashlib,base64,json
def b64(s): return base64.urlsafe_b64encode(s).rstrip(b'=').decode()
h=b64(json.dumps({'alg':'HS256','typ':'JWT'}).encode())
p=b64(json.dumps({'role':'$DB_ROLE'}).encode())
sig=b64(hmac.new('$STATE_DB_POSTGREST_JWT_SECRET'.encode(),f'{h}.{p}'.encode(),hashlib.sha256).digest())
print(f'{h}.{p}.{sig}')
")
DB_AUTH=(-H "Authorization: Bearer $DB_TOKEN")
DB_JSON=(-H "Content-Type: application/json")
DB_RETURN=(-H "Prefer: return=representation")

Required environment variables:

Variable Purpose
STATE_DB_POSTGREST_URL PostgREST endpoint (e.g. http://host:3000)
STATE_DB_POSTGREST_JWT_SECRET HMAC secret for signing JWT tokens
STATE_DB_POSTGREST_ROLE PostgreSQL role for JWT claim (default: web_anon)

Table Schema

Table: skill_state

Column Type Note
id BIGSERIAL PRIMARY KEY
skill_name TEXT e.g. 'food-tracker', 'dca'
key1 TEXT primary sub-key, e.g. 'entry', 'config'
key2 TEXT nullable, second-level key
key3 TEXT nullable, third-level key
key4 TEXT nullable, fourth-level key
key5 TEXT nullable, fifth-level key
data JSONB schemaless payload
created_at TIMESTAMPTZ DEFAULT NOW()
updated_at TIMESTAMPTZ DEFAULT NOW(), auto-updated via trigger

Index: idx_skill_state_keys on (skill_name, key1, key2, key3, key4, key5). PostgreSQL leftmost prefix matching means queries on (skill_name), (skill_name, key1), (skill_name, key1, key2), etc. all use this single index efficiently.

Operations

INSERT

curl -s -X POST "$DB_URL" "${DB_AUTH[@]}" "${DB_JSON[@]}" "${DB_RETURN[@]}" \
  -d '{
    "skill_name": "food-tracker",
    "key1": "entry",
    "data": {"meal": "lunch", "items": ["rice", "chicken"], "phosphorus_mg": 250}
  }'

Multi-key insert:

curl -s -X POST "$DB_URL" "${DB_AUTH[@]}" "${DB_JSON[@]}" "${DB_RETURN[@]}" \
  -d '{
    "skill_name": "expense-tracker",
    "key1": "entry",
    "key2": "food",
    "key3": "2026-03",
    "data": {"amount": 250, "description": "lunch"}
  }'

QUERY

Base form: curl -s "$DB_URL?<filters>" "${DB_AUTH[@]}"

Common filter patterns:

Filter Query string example
By skill_name ?skill_name=eq.food-tracker&order=created_at.desc
By skill_name + key1 ?skill_name=eq.food-tracker&key1=eq.entry&order=created_at.desc
By skill_name + key1 + key2 ?skill_name=eq.expense-tracker&key1=eq.entry&key2=eq.food
By 3 keys ?skill_name=eq.project&key1=eq.task&key2=eq.backend&key3=eq.sprint-12
Null key check ?skill_name=eq.my-skill&key2=is.null
Date range ?skill_name=eq.food-tracker&created_at=gte.2026-03-01T00:00:00Z&created_at=lt.2026-03-15T00:00:00Z
Select columns ?skill_name=eq.dca&select=id,data,created_at
Pagination ?skill_name=eq.food-tracker&order=created_at.desc&limit=10&offset=0

Example:

curl -s "$DB_URL?skill_name=eq.food-tracker&key1=eq.entry&order=created_at.desc&limit=10" \
  "${DB_AUTH[@]}"

JSONB Filters

PostgREST data->>field syntax for JSONB filtering. Append these to query strings:

Filter type Query string example
Top-level field &data->>asset=eq.BTC
String match &data->>meal=eq.lunch
Numeric comparison &data->>phosphorus_mg=gt.200
Combined with date &data->>asset=eq.BTC&created_at=gte.2026-03-01T00:00:00Z

Example:

curl -s "$DB_URL?skill_name=eq.dca&data->>asset=eq.BTC&order=created_at.desc" \
  "${DB_AUTH[@]}"

UPDATE

curl -s -X PATCH "$DB_URL?id=eq.42" "${DB_AUTH[@]}" "${DB_JSON[@]}" "${DB_RETURN[@]}" \
  -d '{
    "data": {"meal": "lunch", "items": ["rice", "chicken", "egg"], "phosphorus_mg": 350}
  }'

DELETE

curl -s -X DELETE "$DB_URL?id=eq.42" "${DB_AUTH[@]}" "${DB_RETURN[@]}"

Delete by skill_name + key1:

curl -s -X DELETE "$DB_URL?skill_name=eq.dca&key1=eq.config" "${DB_AUTH[@]}" "${DB_RETURN[@]}"

Delete by multi-key:

curl -s -X DELETE "$DB_URL?skill_name=eq.expense-tracker&key1=eq.entry&key2=eq.food&key3=eq.2026-03" \
  "${DB_AUTH[@]}" "${DB_RETURN[@]}"

Key Design Guidelines

  1. One skill_name per skill — never write to another skill's namespace.
  2. Use key1 as the record type — equivalent to a "table name" within your skill (e.g. entry, config, portfolio).
  3. Use key2-key5 for natural hierarchy — if your data has inherent groupings (category, date-period, entity-id), promote them to key columns rather than filtering on JSONB fields. This makes queries faster and more readable.
  4. Leave unused keys as null — most skills will only need key1 or key1+key2. Do not fill keys just to fill them.
  5. Put dates inside data — created_at is the DB insert time. If your skill cares about a logical date (e.g. "the date the user ate lunch"), store it as a field in data so you can filter with data->>date=eq.2026-03-14.
  6. Keep data flat when possible — {"asset": "BTC", "amount": 100} is easier to query than {"details": {"asset": "BTC", "amount": 100}} because PostgREST JSONB filtering works best on top-level fields.
  7. Use limit=1 for singleton reads — when fetching config or the latest entry, always add &limit=1 to avoid pulling unnecessary rows.
  8. Sort by created_at.desc for latest-first — default ordering for most queries.

Integration Guide for Skills

This section is written for skills (and the agents executing them) that need persistent state.

Step 1: Reference This Skill

Add this line at the top of your skill's SKILL.md where state management is needed:

For state management, read and follow the protocol in skills/state-db/SKILL.md

Step 2: Design Your State

Plan how your skill organizes records using skill_name and key1-key5 — a six-level namespace:

  • skill_name — your skill's unique identifier. One skill = one skill_name.
  • key1 (required by convention) — record type / "table" within your skill (e.g. entry, config, portfolio).
  • key2-key5 (optional) — additional hierarchy levels. Each skill decides what these mean.
  • data — the actual payload. Schemaless JSONB.

Step 3: Document Your State Schema

In your SKILL.md, document the keys and data shapes your skill uses:

## State Schema (via state-db)

skill_name: `my-skill`

| key1 | key2 | key3 | purpose | data fields |
|------|------|------|---------|-------------|
| entry | (null) | (null) | individual records | `{date, amount, category}` |
| entry | food | (null) | food-specific records | `{date, amount, item}` |
| config | (null) | (null) | user preferences | `{currency, timezone}` |
| summary | 2026-03 | (null) | monthly rollup | `{total, breakdown}` |

Key Naming Conventions

Each skill documents what key1-key5 means in its own SKILL.md. Common patterns:

Level Common usage
key1 Record type: entry, config, summary, portfolio, transaction
key2 Category or entity: food, transport, BTC, daily, monthly
key3 Time period or sub-category: 2026-03, sprint-12
key4-key5 Rarely needed. Reserved for deeply hierarchical data.

Rule of thumb: if you're putting a value in data purely to filter on it, consider promoting it to a key column instead.

State Design Patterns

Pattern 1: Append-Only Log

For skills that record events over time (meals, transactions, logs). Each action creates a new row — never update, just insert.

skill_name: "food-tracker"
key1: "entry"

# Log a meal
curl -s -X POST "$DB_URL" "${DB_AUTH[@]}" "${DB_JSON[@]}" "${DB_RETURN[@]}" \
  -d '{
    "skill_name": "food-tracker",
    "key1": "entry",
    "data": {"date": "2026-03-14", "meal": "lunch", "items": ["rice", "chicken"], "phosphorus_mg": 250, "potassium_mg": 400}
  }'

# Query today's entries
curl -s "$DB_URL?skill_name=eq.food-tracker&key1=eq.entry&data->>date=eq.2026-03-14&order=created_at.asc" \
  "${DB_AUTH[@]}"

Pattern 2: Singleton Config

For skills that store one config record. Query first, then INSERT or UPDATE by id. Safe for single-agent use.

skill_name: "my-skill"
key1: "config"

# Read existing config
EXISTING=$(curl -s "$DB_URL?skill_name=eq.my-skill&key1=eq.config&limit=1" "${DB_AUTH[@]}")

# If empty [] -> INSERT new config
curl -s -X POST "$DB_URL" "${DB_AUTH[@]}" "${DB_JSON[@]}" "${DB_RETURN[@]}" \
  -d '{
    "skill_name": "my-skill",
    "key1": "config",
    "data": {"currency": "THB", "timezone": "Asia/Bangkok"}
  }'

# If exists -> UPDATE by id (extract id from EXISTING with jq)
ID=$(echo "$EXISTING" | jq -r '.[0].id')
curl -s -X PATCH "$DB_URL?id=eq.$ID" "${DB_AUTH[@]}" "${DB_JSON[@]}" "${DB_RETURN[@]}" \
  -d '{"data": {"currency": "USD", "timezone": "Asia/Bangkok"}}'

Pattern 3: Keyed Entities

For skills that manage distinct entities. Use key1 for entity type and key2 for specific entity — avoids JSONB filtering for the most common queries.

skill_name: "dca"
key1: "portfolio"   key2: (null)    -> each row = one asset
key1: "transaction" key2: "BTC"     -> buy/sell events for BTC
key1: "transaction" key2: "ETH"     -> buy/sell events for ETH
key1: "config"      key2: (null)    -> single row for settings

# Add an asset to portfolio
curl -s -X POST "$DB_URL" "${DB_AUTH[@]}" "${DB_JSON[@]}" "${DB_RETURN[@]}" \
  -d '{
    "skill_name": "dca",
    "key1": "portfolio",
    "data": {"asset": "BTC", "total_invested": 50000, "total_units": 0.85}
  }'

# Find specific asset
curl -s "$DB_URL?skill_name=eq.dca&key1=eq.portfolio&data->>asset=eq.BTC&limit=1" \
  "${DB_AUTH[@]}"

# List all BTC transactions (key2 filters by asset — uses index, no JSONB scan)
curl -s "$DB_URL?skill_name=eq.dca&key1=eq.transaction&key2=eq.BTC&order=created_at.desc" \
  "${DB_AUTH[@]}"

Pattern 4: Time-Series with Aggregation

For skills that need both raw data and periodic summaries. Use key1 for record type, key2 for aggregation level, and optionally key3 for specific period.

skill_name: "expense-tracker"
key1: "entry"    key2: (null)      -> individual expenses
key1: "summary"  key2: "daily"     -> one row per day with totals
key1: "summary"  key2: "monthly"   -> one row per month
key1: "summary"  key2: "monthly"   key3: "2026-03" -> specific month

# Insert daily summary
curl -s -X POST "$DB_URL" "${DB_AUTH[@]}" "${DB_JSON[@]}" "${DB_RETURN[@]}" \
  -d '{
    "skill_name": "expense-tracker",
    "key1": "summary",
    "key2": "daily",
    "data": {"date": "2026-03-14", "total": 1250, "count": 5, "categories": {"food": 800, "transport": 450}}
  }'

# Query all monthly summaries
curl -s "$DB_URL?skill_name=eq.expense-tracker&key1=eq.summary&key2=eq.monthly&order=created_at.desc" \
  "${DB_AUTH[@]}"

# Query specific month summary
curl -s "$DB_URL?skill_name=eq.expense-tracker&key1=eq.summary&key2=eq.monthly&key3=eq.2026-03&limit=1" \
  "${DB_AUTH[@]}"

Response Format & Error Handling

All PostgREST responses return JSON arrays. A successful INSERT/UPDATE with Prefer: return=representation returns the created/updated rows. An empty result returns [].

Non-2xx responses return:

{"code": "PGRST...", "message": "...", "details": "...", "hint": "..."}

Error-checked curl pattern:

RESULT=$(curl -s -w "\n%{http_code}" -X POST "$DB_URL" "${DB_AUTH[@]}" "${DB_JSON[@]}" "${DB_RETURN[@]}" \
  -d '{"skill_name": "test", "data": {}}')
HTTP_CODE=$(echo "$RESULT" | tail -1)
BODY=$(echo "$RESULT" | sed '$d')

Database Setup

SQL to create the skill_state table, index, and auto-update trigger on a new PostgreSQL database:

CREATE TABLE IF NOT EXISTS skill_state (
  id BIGSERIAL PRIMARY KEY,
  skill_name TEXT NOT NULL,
  key1 TEXT,
  key2 TEXT,
  key3 TEXT,
  key4 TEXT,
  key5 TEXT,
  data JSONB NOT NULL DEFAULT '{}',
  created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
  updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
);

CREATE INDEX IF NOT EXISTS idx_skill_state_keys
  ON skill_state (skill_name, key1, key2, key3, key4, key5);

CREATE OR REPLACE FUNCTION update_updated_at()
RETURNS TRIGGER AS $$
BEGIN
  NEW.updated_at = NOW();
  RETURN NEW;
END;
$$ LANGUAGE plpgsql;

DROP TRIGGER IF EXISTS trg_skill_state_updated_at ON skill_state;
CREATE TRIGGER trg_skill_state_updated_at
  BEFORE UPDATE ON skill_state
  FOR EACH ROW EXECUTE FUNCTION update_updated_at();

Migration from v2 (Supabase) to v3 (PostgREST)

If your skill previously used the Supabase-based state-db:

  1. Environment variables: Replace STATE_DB_SUPABASE_URL and STATE_DB_SUPABASE_ANON_KEY with STATE_DB_POSTGREST_URL, STATE_DB_POSTGREST_JWT_SECRET, and optionally STATE_DB_POSTGREST_ROLE
  2. URL path: Remove /rest/v1/ prefix — PostgREST uses $URL/skill_state directly
  3. Auth headers: Remove apikey header. Use only Authorization: Bearer <JWT>
  4. Shell variables: Rename SB_URL → DB_URL, SB_AUTH → DB_AUTH, SB_JSON → DB_JSON, SB_RETURN → DB_RETURN
  5. Query syntax: No changes — all filters, operators, and JSONB syntax are identical
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