Context Summarization Plugin

When a conversation is about to exceed the model's context window, this plugin
shrinks the prompt so the turn can still run. It keeps system prompts and the
most recent messages, and — by default — asks a model to summarize the middle
instead of dropping it silently. If summarization is off or fails, it falls
back to truncation.

It also retries after a context-window error from the model, using the same
shrink-and-retry path so a long conversation is more likely to continue than
to fail outright.

Configuration

plugins:
  - module: codumentor.plugins.context_summarization
    class: ContextSummarizationPlugin
    args:
      enabled: true
      max_context_tokens: 128000
      safety_margin: 1000
      min_recent_messages: 5
      split_ratio: 0.7
      enable_summarization: true

Parameters

• enabled (optional): Whether the plugin is active (default: true)
• max_context_tokens (optional): Context limit used when the model has no entry in model_context_limits (default: 128000)
• safety_margin (optional): Tokens reserved for the model's reply (default: 1000)
• min_recent_messages (optional): Minimum number of recent conversation messages to keep uncompressed (default: 5)
• split_ratio (optional): Fraction of the older conversation eligible for summarization / removal, from 0.0 to 1.0 (default: 0.7)
• enable_summarization (optional): Summarize the dropped middle with an LLM instead of only deleting it (default: true)
• summarization_prompt_template (optional): Prompt template used for that summary (default: "context_summarization.jinja2")
• min_messages_for_summary (optional): Do not bother summarizing unless at least this many messages would be condensed (default: 3)
• model_context_limits (optional): Per-model context limits. Omitted by default (empty). Example:

args:
  model_context_limits:
    "Qwen3-235B-A22B-Instruct-2507": 262144

Aggressive truncation for small models

plugins:
  - module: codumentor.plugins.context_summarization
    class: ContextSummarizationPlugin
    args:
      enabled: true
      max_context_tokens: 16385
      safety_margin: 500
      min_recent_messages: 3
      split_ratio: 0.8

What you see

When a turn is summarized or truncated, a transcript card reports how many
messages were condensed, how many were kept, and roughly how many tokens were
saved. A pending card appears while summarization is running.

Each user can hide those cards in Settings (Show Summarization Cards,
on by default).

Notes

• System messages are always kept. Recent messages are kept up to min_recent_messages; older content is summarized (or removed).
• Summaries from earlier turns are reused when the older history has not changed, so you are not charged a fresh summarization call every turn.
• For a proactive, every-turn compression scheme with topic-shift detection, see Context Management.