# Context reference

> The forms and numbers behind the context: the file and its edits, the budget, eviction, the stub, recall and checkpoints.

Source: https://nodecode.ai/docs/context-reference
Updated: 2026-11-03

The story is on [Context](https://nodecode.ai/docs/context). This page is the detail.

## The file

`(context)` writes the session's context to `context/STORE/SESSION/context.txt` under the home and returns its path. Edit it with any file verb, a shell command or Lisp. The first line names the export: keep it. Each message below it is a block under a `[[m:NONCE ID ROLE]]` line.

| Edit | What the next request reads |
| --- | --- |
| Keep | The message byte for byte, so it stays cached. |
| Delete | Nothing. A deleted tool block takes its call with it. |
| Rewrite | The edited text. An edited result ends with the line that recalls the original. |
| Note | Text under a `[[note]]` line, read as the agent's own words. |
| Restore | A removed block's header written back: the original message. |

`(context :drop SPANS :keep IDS :note TEXT)` makes the same edit without the file. Every tool result ends with its seq, `[seq 57]`.

| Keyword | Takes |
| --- | --- |
| `:drop` | `t`, or seqs, ids and `(from . to)` spans. |
| `:keep` | Seqs held back from the drop. |
| `:note` | A note kept at the end. |

The next model request takes the edit or refuses it and says why, in `context.receipt.txt`. It refuses an edit whose first line changed, or one made before another edit was taken. The log is never edited: recall still reads every original. Messages before the first change keep the provider's cache.

## Budget

The budget is the model's context window. The first source with a number wins.

| Order | Source |
| --- | --- |
| 1 | `NODECODE_CONTEXT_TOKENS` |
| 2 | `providers.<id>.models[].context_window` in `config.jsonc` |
| 3 | Overrides recorded in the running image |
| 4 | The models.dev cache |

A window no source knows is never evicted ahead of time. A request rejected as too large records a ceiling, and that ceiling is the budget from then on. `/context` shows the window and what fills it.

## Eviction

| Setting | Value |
| --- | --- |
| Warns at | 85% of the budget, once |
| Evicts | At the next request still over 85% |
| Evicts down to | 50% of the budget |
| Order | Finished turns, oldest first and whole; then the running turn's older rounds |
| Never | The running turn's ask and newest round |

A stub stands where the turns were: `[history evicted: seq A–B · N turns · recall: (recall-log :match "text" :before B+1)]`. It carries the `;;` first line of every evicted cell and the agent's own notes.

`/evict [percent | through TURN]` evicts by hand (alias `/compact`, default 50%). The newest turn always stays.

## Recall

| Form | Reads |
| --- | --- |
| `(recall-log :match "text" :before N :limit 20)` | This session's log, oldest first, bodies clipped to 200 characters. `:match` is SQL LIKE. |
| `(recall-entry N)` | The one event at seq N, whole. |
| `(recall-search "words")` | Every session, newest first. Every word must appear. |

Recall reads the sessions this one forked from, and turns an undo hid.

## Checkpoints

| Command | Does |
| --- | --- |
| `/tree` | Opens the session tree: continue from a turn, or rewind to it. |
| `/undo` | Rewinds the last turn, and its file changes. |
| `/redo` | Returns to the branch the last rewind left. |
| `/fork` | Forks a new session here. |

A rewind deletes nothing. See [Sessions](https://nodecode.ai/docs/sessions).