Module output_tail 

A command’s own output: the tail of the file the CLI streams it to.

The CLI’s local-bash tasks write the command’s stdout to a file on disk rather than sending it over the wire (confirmed in ~/Projects/forge/.claude/skills/claude-cli-upgrade/reference-captures/monitor.jsonl), so the tail is a file read. The readers are the transport - which resolves the path from its held conversation and answers a view’s ReadCallOutput with the result - and the views that hold a path already (a view tails a Monitor’s file on its own tick).

Two ways a path is found, and the ending frame’s own word wins when both exist: task_notification.output_file names the file when the task ends, and until then the path is composed from the task id the wire carries (compose_task_output_path, under task_output_base - both crate-internal, so named rather than linked). Neither reads the launch sentence: forge resolves the file structurally, never from prose.

Constants

CALL_OUTPUT_MAX_LINES

How many lines of a call’s output a ReadCallOutput answers with.

TAIL_WINDOW_BYTES

Largest slice of the file read at a time. Output files grow without bound (cargo build, npm install) and this runs inline on a view’s own tick, so the read seeks to within this window of the end rather than reading the whole file each time. 64 KiB comfortably holds the last few lines at any realistic line length.

Functions

read_output_file_tail

Read the last max_lines lines of path into a Vec ordered oldest-first. Returns None on any read error (file missing, permission denied, a read that failed) so the caller can distinguish “could not read, keep the tail already held” from “the file is genuinely empty”. The empty-file case returns Some(vec![]).

resolve_call_output_path

The file a call’s output went to, from the frames a conversation carries.