Variables API

beginner 🤖 LLM-friendly 1 min · 217 words Updated: 2026-06-27 English

Fast key-value store for LLM state — counters, flags, last-seen timestamps, partial progress.

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Variables API

The Variables API is a fast key-value store for ephemeral state. Unlike memories (which are indexed, searchable, and structured), variables are optimized for quick read/write access — perfect for counters, flags, and session state.

Endpoints

POST /var

Set or update a variable.

curl -X POST https://synapse.schaefer.zone/var \
  -H "Authorization: Bearer YOUR_MIND_KEY" \
  -H "Content-Type: application/json" \
  -d '{"key": "last_session_at", "value": "2026-06-27T14:00:00Z"}'

GET /var/:key

Get a single variable.

curl -H "Authorization: Bearer YOUR_MIND_KEY" \
     https://synapse.schaefer.zone/var/last_session_at

Response:

{ "key": "last_session_at", "value": "2026-06-27T14:00:00Z", "updated_at": "..." }

GET /var

List variable names + metadata. Values are redacted (ex RUN-461, task 7103c3c1: the listing once returned every value in cleartext — including shared account tokens/PATs). Fetch a value individually via GET /var/:key (typed secret vars are human-only: Mind-Key auth gets 403, use the resolver pattern for functional access).

curl -H "Authorization: Bearer YOUR_MIND_KEY" \
     https://synapse.schaefer.zone/var

Response (v1.65.0+):

{ "variables": { "last_session_at": { "scope": "mind", "type": "string", "has_secret": false, "updated_at": 1790000000 } }, "count": 1, "scopes": { "last_session_at": "mind" }, "redacted": true }

DELETE /var/:key

Delete a variable.

curl -X DELETE -H "Authorization: Bearer YOUR_MIND_KEY" \
     https://synapse.schaefer.zone/var/last_session_at

When to Use Variables vs Memory

Use Case	Use
User name, preferences	Memory (searchable, structured)
Last session timestamp	Variable (ephemeral state)
Counter (e.g. messages sent)	Variable (frequent updates)
Workflow state ("step 3 of 5 done")	Variable (transient)
Long-form project notes	Memory (full-text indexed)
Reusable scripts	Script store (named, versioned)

Common Patterns

Track last session

# At session end
curl -X POST .../var -d '{"key": "last_session_at", "value": "'$(date -Iseconds)'"}'

# At session start
LAST=$(curl .../var/last_session_at | jq -r .value)
curl .../memory/diff?since=$(date -d "$LAST" +%s)

Counter pattern

# Increment
N=$(curl .../var/api_calls | jq -r .value)
curl -X POST .../var -d "{\"key\": \"api_calls\", \"value\": $((N+1))}"

Feature flags

curl -X POST .../var -d '{"key": "feature_x_enabled", "value": "true"}'

# Check
ENABLED=$(curl .../var/feature_x_enabled | jq -r .value)
if [ "$ENABLED" = "true" ]; then ... fi

Next Steps

Memory API — for structured, searchable data
Cron & Scheduler