merge-worktree does not accept a session ID when --all is se

Error message

merge-worktree does not accept a session ID when --all is set

What it means

Argument-conflict error from the MergeWorktree command handler in ecc2/src/main.rs. When --all is set together with a session_id, the handler bails: "merge-worktree does not accept a session ID when --all is set". The --all branch calls merge_ready_worktrees across every session, so naming one session is contradictory.

Source

Thrown at ecc2/src/main.rs:2072

                    println!("{}", serde_json::to_string_pretty(&reports)?);
                } else {
                    println!("{}", serde_json::to_string_pretty(&reports[0])?);
                }
            } else {
                println!("{}", format_worktree_resolution_reports_human(&reports));
            }
            if check {
                std::process::exit(worktree_resolution_reports_exit_code(&reports));
            }
        }
        Some(Commands::MergeWorktree {
            session_id,
            all,
            json,
            keep_worktree,
        }) => {
            if all && session_id.is_some() {
                return Err(anyhow::anyhow!(
                    "merge-worktree does not accept a session ID when --all is set"
                ));
            }
            if all {
                let outcome = session::manager::merge_ready_worktrees(&db, !keep_worktree).await?;
                if json {
                    println!("{}", serde_json::to_string_pretty(&outcome)?);
                } else {
                    println!("{}", format_bulk_worktree_merge_human(&outcome));
                }
            } else {
                let id = session_id.unwrap_or_else(|| "latest".to_string());
                let resolved_id = resolve_session_id(&db, &id)?;
                let outcome =
                    session::manager::merge_session_worktree(&db, &resolved_id, !keep_worktree)
                        .await?;
                if json {
                    println!("{}", serde_json::to_string_pretty(&outcome)?);

View on GitHub (pinned to 01e15490f0)

Solutions

Drop either --all or the session id.
Check --help for the mutual exclusivity.
Fix any wrapper script that unconditionally appends an id.

Example fix

# before
$ ecc merge-worktree --all abc123

# after (pick one)
$ ecc merge-worktree --all
$ ecc merge-worktree abc123

Defensive patterns

Strategy: validation

Validate before calling

if all && session_id.is_some() {
    eprintln!("--all cannot be combined with a session id");
    return Ok(());
}

Type guard

fn args_consistent(all: bool, session_id: &Option<String>) -> bool {
    !(all && session_id.is_some())
}

Try / catch

if all {
    if session_id.is_some() {
        eprintln!("ignoring session id because --all was set");
    }
    let outcome = session::manager::merge_ready_worktrees(&db, !keep_worktree).await?;
    // ...
} else {
    // single-session merge
}

Prevention

Read --help to learn which flags are mutually exclusive.
Use clap's `conflicts_with` to enforce mutual exclusivity at parse time.
Audit wrapper scripts that append positional args unconditionally.
Prefer explicit --all or an explicit id, never both.

When it happens

Trigger: Running `merge-worktree --all <session_id>` such that both `all` is true and `session_id` is Some.

Common situations: User assumed --all plus an id scopes the merge; a wrapper script always appends an id; copy-paste from a single-session invocation.

Related errors

AI-assisted analysis of affaan-m/ECC@01e15490f0 (2026-08-13). Data as JSON: /api/errors/2cc50a286fc5e7bf. Report an issue: GitHub.