# Sessions

What Relayhistory records per session: events, subagent trees, tool calls, file edits, markers, and token usage — and how it reports gaps.

Rendered page: https://agentrelay.com/docs/relayhistory/sessions
Markdown endpoint: https://agentrelay.com/docs/relayhistory/markdown/sessions.md

---

A session is one conversation in one harness, identified by its **source** and **session id** together. Provider ids collide — a Codex id and a Claude id can be the same string — so every per-session read names both.

## Evidence, not summaries

Relayhistory stores what the harness wrote: prompts, assistant text, tool calls with their arguments and results, file edits with their patches, and per-request token counts. Nothing is summarized away.

Harnesses don't all record the same things, and Relayhistory says so rather than guessing:

- **Hydration reports a capability** for each session — `full`, `partial`, or `shallow_only` — so thin coverage is distinguishable from something that never happened.
- **Missing fields are reported as unavailable.** Cursor transcripts carry assistant prose and every tool call, but no tool output, model id, or token usage. Older Grok builds log no per-turn billing tokens; their context-window figure is kept as a proxy and labeled as one.
- **Null usage means no evidence**, never an assumed zero.

Ask what a provider's parser can record with `get_source_capabilities` over [MCP](/docs/relayhistory/mcp).

## Events

```bash
ai-hist events SESSION_ID --limit 200
```

The normalized timeline of a session: user turns, assistant turns, tool calls, and tool results, in order. Pages are bounded and deterministic; pass the returned cursor back to continue.

## Subagent trees

Sessions that delegate to subagents form a tree.

```bash
ai-hist sessions relationships codex SESSION_ID   # direct parents and children
ai-hist sessions tree codex SESSION_ID --max-depth 8
```

Each relationship reports how its child was identified:

- **`observed`** — the provider named the child, so it is a real session you can open on its own.
- **`unlinked`** — the provider recorded a delegation but no stable child id. The child's output stays attributed to the parent, and the relationship keeps the evidence that established it. An id is never invented.

Every event keeps the id of the session that produced it; walking a tree never rewrites a child's event as the parent's.

## Tool calls and file edits

```bash
ai-hist sessions tools claude SESSION_ID
ai-hist sessions edits claude SESSION_ID
```

Structured, paged reads of one session's recorded tool calls and file edits. Stored provider JSON is parsed into `args` and `structuredPatch`; when it can't be parsed, the value is `null` and the raw string stays available, so one unreadable payload never fails a page.

## Markers

```bash
ai-hist sessions markers claude SESSION_ID
```

Records a provider wrote that aren't transcript events: compaction and summary boundaries, provider system rows, non-text content blocks, and agent lifecycle events. Each has a classified `kind` and the provider's own `subkind`; anything unclassified is kind `unknown`.

## Token usage

```bash
ai-hist sessions usage claude SESSION_ID
```

A provider-neutral rollup of token usage for one session, as the provider reported it. Per-request detail is available through MCP `get_session_requests`, with duplicate copies collapsed so rows can be summed. Cost appears only when the source data carried one; Relayhistory never computes it.