OpenAI server compaction

A vendored Pi extension that uses OpenAI's Responses compaction protocol for GPT models while preserving Pi's session, tree, and fallback behavior.

This fork is based on algal/pi-openai-server-compaction and retains its MIT license. It is adapted for this dotfiles repository and Pi 0.82.

Scope

Remote compaction is intentionally limited to GPT models on these native Pi providers:

openai/* using openai-responses
openai-codex/* using openai-codex-responses

Other models and providers are untouched and continue using Pi's default compaction.

Compaction behavior

Pi remains responsible for deciding when to compact, selecting the cut point, and writing the compaction entry. On session_before_compact, this extension:

asks OpenAI for an opaque compaction item through the Responses API;
generates a portable text summary in parallel;
stores the opaque replacement history in CompactionEntry.details.remoteCompaction; and
replays that history on later requests to the exact same provider/API/model.

If remote compaction fails but the portable summary succeeds, Pi uses that text summary. If neither extension path succeeds, the handler returns control to Pi's default compactor.

The opaque artifact is model-specific. Switching models uses Pi's portable text summary; switching back reconstructs the matching artifact from session JSONL.

Pi 0.82 adaptation

Unlike upstream, this fork does not override Pi's OpenAI provider or install a custom WebSocket transport. It uses Pi 0.82's native HTTP Responses transport. This avoids the upstream WebSocket partial-rendering issue and removes the runtime ws dependency.

Because Pi's full replay payload is not safe to combine with previous_response_id, this fork disables that optimization. It also leaves normal pre-compaction requests unchanged instead of enabling OpenAI's automatic context_management, whose compaction stream events Pi 0.82 does not natively persist. Pi triggers compaction normally; post-compaction requests replay the opaque artifact explicitly.

Data handling

Conversation context is sent to OpenAI during compaction with store: false, and returned encrypted artifacts are stored in Pi's local session JSONL. The artifacts are not human-readable. OpenAI's normal API data-handling and abuse monitoring policies still apply.

Configuration

Configuration is read from:

~/.pi/agent/openai-server-compaction.json
.pi/openai-server-compaction.json (takes precedence)

{
  "enabled": true,
  "notify": false
}

Environment overrides:

PI_OPENAI_SERVER_COMPACTION_ENABLED
PI_OPENAI_SERVER_COMPACTION_NOTIFY

Set PI_OPENAI_SERVER_COMPACTION_ENABLED=0 for a quick rollback, or start Pi with --no-extensions to bypass all extensions.

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