diff --git a/README.md b/README.md
index 2d7017e5..0e87acb8 100644
--- a/README.md
+++ b/README.md
@@ -141,6 +141,23 @@ If you have `uv` [installed](https://docs.astral.sh/uv/getting-started/installat
 make test
 ```
 
+## Shell completion
+
+Optional bash/zsh completion for commands, ticket IDs, statuses, types and flags.
+
+```bash
+./install-completion.sh
+exec "$SHELL"
+```
+
+The installer writes to the standard completion directory for your shell and
+appends the source line to your rc file if needed. To wire it up by hand
+instead, source `ticket-completion.bash` or `ticket-completion.zsh` from your
+`.bashrc` / `.zshrc`.
+
+Ticket IDs are completed from the same `.tickets/` directory `tk` itself
+resolves, so it honours `TICKETS_DIR` and the walk up parent directories.
+
 ## Migrating from Beads
 
 ```bash
diff --git a/install-completion.sh b/install-completion.sh
new file mode 100755
index 00000000..5b7383c7
--- /dev/null
+++ b/install-completion.sh
@@ -0,0 +1,55 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Install shell completion for ticket/tk into the user's completion directory.
+# No sudo, no system paths.
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+DATA_HOME="${XDG_DATA_HOME:-$HOME/.local/share}"
+
+install_bash() {
+    local dir="$DATA_HOME/bash-completion/completions"
+    mkdir -p "$dir"
+    cp "$SCRIPT_DIR/ticket-completion.bash" "$dir/ticket"
+    ln -sf ticket "$dir/tk"
+    echo "bash: installed $dir/ticket"
+    echo "      requires the bash-completion package to be loaded in your shell"
+}
+
+install_zsh() {
+    local dir="$DATA_HOME/zsh/site-functions"
+    mkdir -p "$dir"
+    cp "$SCRIPT_DIR/ticket-completion.zsh" "$dir/_ticket"
+    echo "zsh: installed $dir/_ticket"
+
+    if [[ -f "$HOME/.zshrc" ]] && ! grep -qF "$dir" "$HOME/.zshrc"; then
+        cat >> "$HOME/.zshrc" <<EOF
+
+# ticket completion
+fpath=($dir \$fpath)
+autoload -Uz compinit && compinit
+EOF
+        echo "     added fpath entry to ~/.zshrc"
+    fi
+}
+
+for f in ticket-completion.bash ticket-completion.zsh; do
+    [[ -f "$SCRIPT_DIR/$f" ]] || { echo "missing $f in $SCRIPT_DIR" >&2; exit 1; }
+done
+
+case "${1:-auto}" in
+    bash) install_bash ;;
+    zsh)  install_zsh ;;
+    auto)
+        if [[ -f "$HOME/.bashrc" || "$(basename "${SHELL:-}")" == bash ]]; then
+            install_bash
+        fi
+        if [[ -f "$HOME/.zshrc" || "$(basename "${SHELL:-}")" == zsh ]]; then
+            install_zsh
+        fi
+        ;;
+    *) echo "usage: $0 [bash|zsh|auto]" >&2; exit 1 ;;
+esac
+
+echo
+echo "Restart your shell (exec \"\$SHELL\") to pick it up."
diff --git a/ticket-completion.bash b/ticket-completion.bash
new file mode 100644
index 00000000..62febaa6
--- /dev/null
+++ b/ticket-completion.bash
@@ -0,0 +1,253 @@
+#!/usr/bin/env bash
+# Bash completion for ticket command
+
+# Locate .tickets the same way ticket does: TICKETS_DIR wins, else walk parents
+_ticket_find_dir() {
+    [[ -n "${TICKETS_DIR:-}" ]] && { echo "$TICKETS_DIR"; return 0; }
+
+    local dir="$PWD"
+    while [[ "$dir" != "/" ]]; do
+        if [[ -d "$dir/.tickets" ]]; then
+            echo "$dir/.tickets"
+            return 0
+        fi
+        dir=$(dirname "$dir")
+    done
+
+    [[ -d "/.tickets" ]] && { echo "/.tickets"; return 0; }
+    return 1
+}
+
+# Get all ticket IDs from .tickets directory
+_ticket_get_ids() {
+    local dir
+    dir=$(_ticket_find_dir) || return 0
+    [[ -d "$dir" ]] || return 0
+
+    local ids=()
+    local file
+    for file in "$dir"/*.md; do
+        if [[ -f "$file" ]]; then
+            ids+=("$(basename "$file" .md)")
+        fi
+    done
+    echo "${ids[@]}"
+}
+
+# compopt only exists in bash 4+; degrade quietly on bash 3.2 (macOS default)
+_ticket_nospace() {
+    if type compopt &>/dev/null; then
+        compopt -o nospace 2>/dev/null
+    fi
+    return 0
+}
+
+_ticket_completion() {
+    local cur prev words cword
+    if declare -F _init_completion >/dev/null; then
+        _init_completion || return
+    else
+        # bash-completion is not loaded; derive the same variables ourselves
+        words=("${COMP_WORDS[@]}")
+        cword=$COMP_CWORD
+        cur="${COMP_WORDS[COMP_CWORD]}"
+        prev="${COMP_WORDS[COMP_CWORD-1]}"
+    fi
+
+    # Main commands
+    local commands="create start close reopen status dep undep link unlink ls list ready blocked closed show add-note super edit query migrate-beads help"
+    
+    # Valid statuses
+    local statuses="open in_progress closed"
+    
+    # Commands that need ticket ID(s)
+    local id_commands="start close reopen status show edit add-note"
+    local multi_id_commands="link dep undep unlink"
+
+    # Get the main command (first word after 'ticket')
+    local cmd=""
+    if [[ $cword -ge 1 ]]; then
+        cmd="${words[1]}"
+    fi
+
+    case $cword in
+        1)
+            # Complete main commands
+            COMPREPLY=($(compgen -W "$commands" -- "$cur"))
+            return 0
+            ;;
+        2)
+            case "$cmd" in
+                # Commands that need a ticket ID
+                start|close|reopen|show|edit|add-note)
+                    COMPREPLY=($(compgen -W "$(_ticket_get_ids)" -- "$cur"))
+                    return 0
+                    ;;
+                # status needs ticket ID first
+                status)
+                    COMPREPLY=($(compgen -W "$(_ticket_get_ids)" -- "$cur"))
+                    return 0
+                    ;;
+                # dep has subcommands or ticket ID
+                dep)
+                    COMPREPLY=($(compgen -W "tree cycle $(_ticket_get_ids)" -- "$cur"))
+                    return 0
+                    ;;
+                # Commands that need multiple ticket IDs
+                link|undep|unlink)
+                    COMPREPLY=($(compgen -W "$(_ticket_get_ids)" -- "$cur"))
+                    return 0
+                    ;;
+                # ls can have --status flag
+                ls|list)
+                    if [[ "$cur" == -* ]]; then
+                        COMPREPLY=($(compgen -W "--status= -a -T" -- "$cur"))
+                        [[ ${#COMPREPLY[@]} -eq 1 ]] && [[ "${COMPREPLY[0]}" == *= ]] && _ticket_nospace
+                    fi
+                    return 0
+                    ;;
+                ready|blocked)
+                    if [[ "$cur" == -* ]]; then
+                        COMPREPLY=($(compgen -W "-a -T" -- "$cur"))
+                    fi
+                    return 0
+                    ;;
+                super)
+                    COMPREPLY=($(compgen -W "$commands" -- "$cur"))
+                    return 0
+                    ;;
+                # closed can have --limit flag
+                closed)
+                    if [[ "$cur" == -* ]]; then
+                        COMPREPLY=($(compgen -W "--limit= -a -T" -- "$cur"))
+                        [[ ${#COMPREPLY[@]} -eq 1 ]] && [[ "${COMPREPLY[0]}" == *= ]] && _ticket_nospace
+                    fi
+                    return 0
+                    ;;
+                # create has many options
+                create)
+                    if [[ "$cur" == -* ]]; then
+                        COMPREPLY=($(compgen -W "-d --description --design --acceptance -t --type -p --priority -a --assignee --external-ref --parent --tags" -- "$cur"))
+                    fi
+                    return 0
+                    ;;
+            esac
+            ;;
+        3)
+            case "$cmd" in
+                # status needs status value after ticket ID
+                status)
+                    COMPREPLY=($(compgen -W "$statuses" -- "$cur"))
+                    return 0
+                    ;;
+                # dep can be 'tree' with options or regular dep with ticket ID
+                dep)
+                    if [[ "${words[2]}" == "cycle" ]]; then
+                        return 0
+                    elif [[ "${words[2]}" == "tree" ]]; then
+                        # dep tree needs ticket ID or --full flag
+                        if [[ "$cur" == -* ]]; then
+                            COMPREPLY=($(compgen -W "--full" -- "$cur"))
+                        else
+                            COMPREPLY=($(compgen -W "$(_ticket_get_ids)" -- "$cur"))
+                        fi
+                    else
+                        # Regular dep needs second ticket ID
+                        COMPREPLY=($(compgen -W "$(_ticket_get_ids)" -- "$cur"))
+                    fi
+                    return 0
+                    ;;
+                # undep and unlink need second ticket ID
+                undep|unlink)
+                    COMPREPLY=($(compgen -W "$(_ticket_get_ids)" -- "$cur"))
+                    return 0
+                    ;;
+                # link can have more ticket IDs
+                link)
+                    COMPREPLY=($(compgen -W "$(_ticket_get_ids)" -- "$cur"))
+                    return 0
+                    ;;
+                # create options
+                create)
+                    case "$prev" in
+                        -t|--type|-T)
+                            COMPREPLY=($(compgen -W "bug feature task epic chore" -- "$cur"))
+                            return 0
+                            ;;
+                        -p|--priority)
+                            COMPREPLY=($(compgen -W "0 1 2 3 4" -- "$cur"))
+                            return 0
+                            ;;
+                        --parent)
+                            COMPREPLY=($(compgen -W "$(_ticket_get_ids)" -- "$cur"))
+                            return 0
+                            ;;
+                        -d|--description|--design|--acceptance|-a|--assignee|--external-ref|--tags)
+                            # These need text input, no completion
+                            return 0
+                            ;;
+                        *)
+                            if [[ "$cur" == -* ]]; then
+                                COMPREPLY=($(compgen -W "-d --description --design --acceptance -t --type -p --priority -a --assignee --external-ref --parent --tags" -- "$cur"))
+                            fi
+                            return 0
+                            ;;
+                    esac
+                    ;;
+            esac
+            ;;
+        *)
+            # Handle additional arguments
+            case "$cmd" in
+                # dep tree with --full flag
+                dep)
+                    if [[ "${words[2]}" == "tree" ]]; then
+                        if [[ "${words[3]}" == "--full" ]] && [[ $cword -eq 4 ]]; then
+                            COMPREPLY=($(compgen -W "$(_ticket_get_ids)" -- "$cur"))
+                        elif [[ "$cur" == -* ]] && [[ $cword -eq 4 ]]; then
+                            COMPREPLY=($(compgen -W "--full" -- "$cur"))
+                        fi
+                    fi
+                    return 0
+                    ;;
+                # link can accept multiple ticket IDs
+                link)
+                    COMPREPLY=($(compgen -W "$(_ticket_get_ids)" -- "$cur"))
+                    return 0
+                    ;;
+                # create options can appear at any position
+                create)
+                    case "$prev" in
+                        -t|--type|-T)
+                            COMPREPLY=($(compgen -W "bug feature task epic chore" -- "$cur"))
+                            return 0
+                            ;;
+                        -p|--priority)
+                            COMPREPLY=($(compgen -W "0 1 2 3 4" -- "$cur"))
+                            return 0
+                            ;;
+                        --parent)
+                            COMPREPLY=($(compgen -W "$(_ticket_get_ids)" -- "$cur"))
+                            return 0
+                            ;;
+                        -d|--description|--design|--acceptance|-a|--assignee|--external-ref|--tags)
+                            return 0
+                            ;;
+                        *)
+                            if [[ "$cur" == -* ]]; then
+                                COMPREPLY=($(compgen -W "-d --description --design --acceptance -t --type -p --priority -a --assignee --external-ref --parent --tags" -- "$cur"))
+                            fi
+                            return 0
+                            ;;
+                    esac
+                    ;;
+            esac
+            ;;
+    esac
+
+    return 0
+}
+
+# Register the completion function for the ticket command
+complete -F _ticket_completion ticket
+complete -F _ticket_completion tk
diff --git a/ticket-completion.zsh b/ticket-completion.zsh
new file mode 100644
index 00000000..41d33f77
--- /dev/null
+++ b/ticket-completion.zsh
@@ -0,0 +1,157 @@
+#compdef ticket tk
+
+# Zsh completion for ticket command (also works with 'tk' alias)
+
+# Get all ticket IDs from .tickets directory
+# Locate .tickets the same way ticket does: TICKETS_DIR wins, else walk parents
+_ticket_find_dir() {
+    [[ -n "${TICKETS_DIR:-}" ]] && { echo "$TICKETS_DIR"; return 0; }
+
+    local dir="$PWD"
+    while [[ "$dir" != "/" ]]; do
+        if [[ -d "$dir/.tickets" ]]; then
+            echo "$dir/.tickets"
+            return 0
+        fi
+        dir="${dir:h}"
+    done
+
+    [[ -d "/.tickets" ]] && { echo "/.tickets"; return 0; }
+    return 1
+}
+
+_ticket_get_ids() {
+    local dir
+    dir=$(_ticket_find_dir) || return 0
+    [[ -d "$dir" ]] || return 0
+
+    local ids=()
+    local file
+    for file in "$dir"/*.md(N); do
+        ids+=("${file:t:r}")
+    done
+    echo ${ids[@]}
+}
+
+_ticket() {
+    local line state
+
+    _arguments -C \
+        '1: :->command' \
+        '*::arg:->args'
+
+    case $state in
+        command)
+            local commands=(
+                'create:Create a new ticket'
+                'start:Set status to in_progress'
+                'close:Set status to closed'
+                'reopen:Set status to open'
+                'status:Update ticket status'
+                'dep:Add dependency or show dependency tree'
+                'undep:Remove dependency'
+                'link:Link tickets together'
+                'unlink:Remove link between tickets'
+                'ls:List tickets'
+                'list:List tickets'
+                'ready:List ready tickets'
+                'blocked:List blocked tickets'
+                'closed:List recently closed tickets'
+                'show:Display ticket'
+                'edit:Open ticket in editor'
+                'add-note:Append note to ticket'
+                'query:Output tickets as JSON'
+                'migrate-beads:Import from beads'
+                'super:Bypass plugins and run the built-in command'
+                'help:Show help'
+            )
+            _describe 'command' commands
+            ;;
+        args)
+            local cmd="${line[1]}"
+            case "$cmd" in
+                start|close|reopen|show|edit|add-note)
+                    _arguments "1: :($(_ticket_get_ids))"
+                    ;;
+                status)
+                    case $CURRENT in
+                        2)
+                            _arguments "1: :($(_ticket_get_ids))"
+                            ;;
+                        3)
+                            _arguments "1: :(open in_progress closed)"
+                            ;;
+                    esac
+                    ;;
+                dep)
+                    case $CURRENT in
+                        2)
+                            local subcmds=(
+                                'tree:Show dependency tree'
+                                'cycle:Find dependency cycles in open tickets'
+                            )
+                            _describe 'subcommand' subcmds
+                            _arguments "1: :($(_ticket_get_ids))"
+                            ;;
+                        3)
+                            if [[ "${line[2]}" == "tree" ]]; then
+                                _arguments \
+                                    '--full[Show full tree without deduplication]' \
+                                    "1: :($(_ticket_get_ids))"
+                            else
+                                _arguments "1: :($(_ticket_get_ids))"
+                            fi
+                            ;;
+                        4)
+                            if [[ "${line[2]}" == "tree" ]]; then
+                                _arguments "1: :($(_ticket_get_ids))"
+                            fi
+                            ;;
+                    esac
+                    ;;
+                undep|unlink)
+                    case $CURRENT in
+                        2|3)
+                            _arguments "1: :($(_ticket_get_ids))"
+                            ;;
+                    esac
+                    ;;
+                link)
+                    _arguments "*: :($(_ticket_get_ids))"
+                    ;;
+                ls|list)
+                    _arguments \
+                        '--status=[Filter by status]:status:(open in_progress closed)' \
+                        '-a[Filter by assignee]:assignee:' \
+                        '-T[Filter by type]:type:(bug feature task epic chore)'
+                    ;;
+                ready|blocked)
+                    _arguments \
+                        '-a[Filter by assignee]:assignee:' \
+                        '-T[Filter by type]:type:(bug feature task epic chore)'
+                    ;;
+                closed)
+                    _arguments \
+                        '--limit=[Limit number of results]:limit:' \
+                        '-a[Filter by assignee]:assignee:' \
+                        '-T[Filter by type]:type:(bug feature task epic chore)'
+                    ;;
+                create)
+                    _arguments \
+                        '1:title:' \
+                        '(-d --description)'{-d,--description}'[Description text]:description:' \
+                        '--design[Design notes]:design:' \
+                        '--acceptance[Acceptance criteria]:acceptance:' \
+                        '(-t --type)'{-t,--type}'[Ticket type]:type:(bug feature task epic chore)' \
+                        '(-p --priority)'{-p,--priority}'[Priority]:priority:(0 1 2 3 4)' \
+                        '(-a --assignee)'{-a,--assignee}'[Assignee]:assignee:' \
+                        '--external-ref[External reference]:reference:' \
+                        '--tags[Comma-separated tags]:tags:' \
+                        "--parent[Parent ticket]:parent:($(_ticket_get_ids))"
+                    ;;
+            esac
+            ;;
+    esac
+}
+
+_ticket "$@"
\ No newline at end of file