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Context management

Model context windows are finite. Digitorn helps you keep long chats under the limit with compaction settings in YAML.

What fills the context​

PieceNotes
System promptYour system_prompt and related injects
Tool schemasLarger when many modules are granted
Conversation historyGrows every turn
Memory snapshotGoals / facts when memory is enabled

When token pressure (used / max) crosses your threshold, compaction rewrites older history so recent messages stay intact.

Configure under runtime.context or brain.context​

app.yaml
runtime:
  context:
    max_tokens: 200000          # 0 = auto from the provider when possible
    output_reserved: 4096       # room left for the model reply
    strategy: summarize         # truncate | summarize
    keep_recent: 10             # recent messages kept verbatim
    compression_trigger: 0.75   # pressure that starts compaction
    summary_max_tokens: 1024
    auto_compact: true          # inject a default compact hook

Per-agent override:

app.yaml
agents:
  - id: main
    brain:
      context:
        max_tokens: 32000
        strategy: summarize
        keep_recent: 8

Full field list: App configuration.

Explicit compact hook​

brain.context.keep_recent configures how many recent messages to preserve. On a hook action, the field name is keep_last (not keep_recent):

app.yaml
runtime:
  hooks:
    - id: compact_when_full
      "on": turn_end
      condition:
        type: context_pressure
        threshold: 0.75
      action:
        type: compact_context
        strategy: summarize
        keep_last: 10

If you already declare a compact_context hook, Digitorn does not add a second auto-compact hook on top.

Strategies​

StrategyBehaviour
summarizeOlder turns become a short summary; recent turns stay
truncateDrops oldest turns until pressure is acceptable

Tips for app authors​

  • Prefer auto_compact: true for chat apps unless you need a custom hook.
  • Use a smaller keep_recent / keep_last on long-running background agents.
  • Grant fewer tools if tool schemas dominate the window (discovery).