What causes "target kind is required when target value is provided" in gitbutlerapp/gitbutler?

Prefix the value with its target kind: `but agentlog skim session ` (or branch/change/review as applicable).

target kind is required when target value is provided

Error message

target kind is required when target value is provided

What it means

In crates/but-agentlog/src/cli.rs run_from_dir, the Skim command bails with "target kind is required when target value is provided" when a value is given without a target kind. The match treats (None, Some(_)) as invalid; only both-or-neither are accepted.

Solutions

Prefix the value with its target kind: `but agentlog skim session <value>` (or branch/change/review as applicable).
Pass no filter arguments at all to skim everything, instead of a bare value.
In wrappers/scripts, always emit both arguments together or neither.

Example fix

// before
but agentlog skim abc123
// after
but agentlog skim session abc123

Defensive patterns

Strategy: validation

Validate before calling

# require both or neither
if [ -n "$VALUE" ] && [ -z "$TARGET" ]; then echo "provide a target kind"; exit 1; fi

Prevention

Never pass a bare value to skim; always prefix with branch|session|review|change as supported.
Keep target/value pairs together when constructing CLI args programmatically.
Prefer no-arg skim when filtering intent is unclear.

When it happens

Trigger: Running `but agentlog skim <value>` where the value lands in the `value` positional while `target` is None — the (None, Some(_)) arm bails.

Common situations: Omitting the kind keyword, e.g. `but agentlog skim my-session` instead of `but agentlog skim session my-session`; script argument shifting that drops the kind.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

AI-assisted analysis of gitbutlerapp/gitbutler@58e5313667 (2026-09-18). Data as JSON: /api/errors/a2be1d649d82b375. Report an issue: GitHub.

Appendix: source

Thrown at crates/but-agentlog/src/cli.rs:361

                    let timeline = get_session_timeline_outline(
                        &repo_path,
                        &session_key,
                        status,
                        Some(limit.unwrap_or(DEFAULT_TIMELINE_LIMIT)),
                    )
                    .context("failed to read agent session timeline")?;
                    Ok(CommandOutput::Timeline(timeline))
                }
            }
        }
        Command::Skim { target, value } => {
            let explicit_target = match (target, value) {
                (Some(target), Some(value)) => Some((target, value)),
                (Some(target), None) => {
                    anyhow::bail!("{} target value is required", target.as_str())
                }
                (None, Some(_)) => {
                    anyhow::bail!("target kind is required when target value is provided")
                }
                (None, None) => None,
            };
            let repo_path = if explicit_target.is_some() {
                resolve_read_repo_path(dir)?
            } else {
                resolve_workdir(dir)?
            };
            let (target, value) = match explicit_target {
                Some(target) => target,
                None => skim::resolve_default_branch_target(&repo_path)?,
            };
            let target_key = related_session_target_key(target, &value);
            let sessions = find_related_sessions_limited_by_statuses(
                &repo_path,
                target.related_target(&target_key),
                None,
                &[PublicationStatus::LocalOnly, PublicationStatus::Published],

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