Glossary

• Active run: Work that a pi runtime is currently generating or executing.
• Backend connection: A named Leyline server URL that a window can use for sessions, runtime events, terminal traffic, traces, and exports.
• Capture new runs: The trace-footer control that enables or disables capture for future runs on the selected backend. It does not delete existing traces.
• Compaction: A pi operation that replaces older context with a shorter summary to reduce context use.
• Confirmation card: An extension request above the composer with Confirm and Cancel actions.
• Composer: The input area for prompts, images, shell commands, slash commands, steering, and Up next tasks.
• Context usage: The current number and percentage of model context tokens.
• Deep research session: A pi session whose lead agent plans parallel source work and writes a cited report.
• Elune: The embedded library that stores and displays Leyline run traces. Leyline does not require the standalone Elune server.
• File preview: A view of the current local file on the session's backend, separate from saved tool output.
• Follow-up: An input that pi has accepted to run after the active turn. It appears under Sent to agent, not the editable Up next queue.
• Fork: A new pi session that starts from a selected transcript entry.
• Git review: A read-only desktop pane for staged, working-tree, untracked, and conflicted project changes.
• Held queue: Unsent Up next tasks that wait until you select Resume. Stop and queue edits hold remaining tasks.
• Leyline trash: The directory where Leyline moves a deleted session JSONL file. It is a timestamped leyline-trash directory next to the configured pi session directory.
• MCP tool: A tool from a configured Model Context Protocol server, supplied through pi's native MCP integration.
• Memory: Local Markdown context in global, project, or session scope.
• Native backend: The backend that supplied the current Leyline app.
• Memory Inspector: The Memory drawer for creating, editing, archiving, restoring, and deleting visible memory.
• Observation: A recorded operation within a trace, such as a model call or tool call, with available input, output, timing, usage, and metadata.
• Pi session: A persisted, tree-structured JSONL conversation log managed by pi.
• Project: A working directory that groups sessions in Leyline.
• Project settings: A drawer for project-level agent overrides and metadata. Its Sessions tab filters, sorts, creates, opens, renames, and deletes sessions.
• Prompt inspector: A side pane for one recorded System event's prompt sections, tool changes, and exact event text.
• Research artifact: A completed Markdown report whose numeric citations match the research source ledger.
• Runtime: The live pi session object that runs prompts, tools, shell commands, and model operations.
• Runtime events: The Events drawer data from the selected backend's event stream. This temporary page list is separate from durable traces.
• Sent to agent: Waiting inputs that pi has already accepted. These inputs cannot be edited, reordered, or removed from the queue tray.
• Source ledger: The persisted research list that maps citation numbers to cited, supporting, or excluded sources.
• Session details: A drawer for runtime information, session metadata, and session-level agent overrides.
• Session scope: Data that applies to one session file.
• Steering: A message sent to the active run at its next accepted input point. Use Option+Enter during an active run.
• Subagent: A child pi session that runs a delegated task with isolated context.
• System row: A muted transcript divider for recorded system-prompt and tool changes. Select it to open the prompt inspector.
• Thought: A collapsed or expanded transcript row that contains available model reasoning output.
• Tool row: A collapsed or expanded transcript row for a tool call and its result.
• Trace: A durable record of a captured agent run on one backend. It can retain private prompts and tool results independently of session history.
• Trace explorer: The view across projects on the selected backend, with project, search, and status filters. Open it through the sidebar's Trace explorer icon button.
• Trace inspector: The Session traces view for recorded runs in the selected session.
• Tracing workspace: The expanded timeline and detail view opened through Open workspace. Back returns to its inspector or explorer.
• Transcript: The selected branch of a pi session as Leyline displays it.
• ultrafast: A premium service tier for supported OpenAI Responses models. Its composer chip is off by default and applies to the current runtime/session. Compaction and branch summaries remain Standard.
• Up next: The editable queue of tasks that Leyline sends one at a time when the agent becomes idle. Enter adds a task during an active run.
• Vision agent: The vision_agent tool. It starts a hidden child session to inspect an image for a parent model that cannot receive images.
• Vision model: The image-capable model selected for vision delegation.
• Workbench: The selected-session area with the header, transcript, composer, drawers, and terminal.