Module: ClaudeAgentSDK::SessionMutations

Defined in:
lib/claude_agent_sdk/session_mutations.rb

Overview

Session mutation functions: rename, tag, delete, and fork sessions.

Ported from Python SDK’s _internal/session_mutations.py. Appends typed metadata entries to the session’s JSONL file, matching the CLI pattern. Safe to call from any SDK host process.

Constant Summary collapse

UNICODE_STRIP_RE =

Unicode sanitization — ported from Python SDK / TS sanitization.ts

Iteratively applies NFKC normalization and strips format/private-use/ unassigned characters until stable (max 10 iterations).

/[\u200b-\u200f\u202a-\u202e\u2066-\u2069\ufeff\ue000-\uf8ff]/
FORMAT_CATEGORIES = 
%w[Cf Co Cn].freeze

Class Method Summary collapse

Class Method Details

.delete_session(session_id:, directory: nil) ⇒ Object

Delete a session by removing its JSONL file.

This is a hard delete — the file is removed permanently. For soft-delete semantics, use tag_session(id, ‘__hidden’) and filter on listing instead.

Parameters:

  • session_id (String) —

    UUID of the session to delete

  • directory (String, nil) (defaults to: nil) —

    Project directory path

Raises:

  • (ArgumentError) —

    if session_id is invalid

  • (Errno::ENOENT) —

    if the session file cannot be found



73
74
75
76
77
78
79
80
81
82
83
84
85
86
 
# File 'lib/claude_agent_sdk/session_mutations.rb', line 73

def delete_session(session_id:, directory: nil)
  raise ArgumentError, "Invalid session_id: #{session_id}" unless session_id.match?(Sessions::UUID_RE)

  result = find_session_file_with_dir(session_id, directory)
  raise Errno::ENOENT, "Session #{session_id} not found#{" in project directory for #{directory}" if directory}" unless result

  path = result[0]

  begin
    File.delete(path)
  rescue Errno::ENOENT
    raise Errno::ENOENT, "Session #{session_id} not found"
  end
end

.fork_session(session_id:, directory: nil, up_to_message_id: nil, title: nil) ⇒ ForkSessionResult

Fork a session into a new branch with fresh UUIDs.

Creates a copy of the session transcript (or a prefix up to up_to_message_id) with remapped UUIDs and a new session ID. Sidechains are filtered out, progress entries are excluded from the written output but used for parentUuid chain walking.

Parameters:

  • session_id (String) —

    UUID of the session to fork

  • directory (String, nil) (defaults to: nil) —

    Project directory path

  • up_to_message_id (String, nil) (defaults to: nil) —

    Truncate the fork at this message UUID

  • title (String, nil) (defaults to: nil) —

    Custom title for the fork (auto-generated if omitted)

Returns:

Raises:

  • (ArgumentError) —

    if session_id or up_to_message_id is invalid

  • (Errno::ENOENT) —

    if the session file cannot be found



102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
 
# File 'lib/claude_agent_sdk/session_mutations.rb', line 102

def fork_session(session_id:, directory: nil, up_to_message_id: nil, title: nil) # rubocop:disable Metrics/MethodLength
  raise ArgumentError, "Invalid session_id: #{session_id}" unless session_id.match?(Sessions::UUID_RE)

  raise ArgumentError, "Invalid up_to_message_id: #{up_to_message_id}" if up_to_message_id && !up_to_message_id.match?(Sessions::UUID_RE)

  result = find_session_file_with_dir(session_id, directory)
  raise Errno::ENOENT, "Session #{session_id} not found#{" in project directory for #{directory}" if directory}" unless result

  file_path, project_dir = result
  file_size = File.size(file_path)
  raise ArgumentError, "Session #{session_id} has no messages to fork" if file_size.zero?

  transcript, content_replacements = parse_fork_transcript(file_path)
  transcript.reject! { |e| e['isSidechain'] }
  raise ArgumentError, "Session #{session_id} has no messages to fork" if transcript.empty?

  if up_to_message_id
    cutoff = transcript.index { |e| e['uuid'] == up_to_message_id }
    raise ArgumentError, "Message #{up_to_message_id} not found in session #{session_id}" unless cutoff

    transcript = transcript[0..cutoff]
  end

  # Build UUID mapping (including progress entries for parentUuid chain walk)
  uuid_mapping = {}
  transcript.each { |e| uuid_mapping[e['uuid']] = SecureRandom.uuid }

  by_uuid = transcript.to_h { |e| [e['uuid'], e] }

  # Filter out progress messages from written output
  writable = transcript.reject { |e| e['type'] == 'progress' }
  raise ArgumentError, "Session #{session_id} has no messages to fork" if writable.empty?

  forked_session_id = SecureRandom.uuid
  now = Time.now.utc.strftime('%Y-%m-%dT%H:%M:%S.%3NZ')

  lines = writable.each_with_index.map do |original, i|
    build_forked_entry(original, i, writable.size, uuid_mapping, by_uuid,
                       forked_session_id, session_id, now)
  end

  # Append content-replacement entry if any
  if content_replacements && !content_replacements.empty?
    lines << JSON.generate({
                             'type' => 'content-replacement',
                             'sessionId' => forked_session_id,
                             'replacements' => content_replacements
                           })
  end

  # Derive title — only read head/tail chunks when we need to generate one
  fork_title = title&.strip
  fork_title = "#{derive_fork_title(file_path, file_size)} (fork)" if fork_title.nil? || fork_title.empty?

  lines << JSON.generate({
                           'type' => 'custom-title',
                           'sessionId' => forked_session_id,
                           'customTitle' => fork_title
                         })

  fork_path = File.join(project_dir, "#{forked_session_id}.jsonl")
  io = nil
  fd = IO.sysopen(fork_path, File::WRONLY | File::CREAT | File::EXCL, 0o600)
  begin
    io = IO.new(fd)
    io.write("#{lines.join("\n")}\n")
  ensure
    if io
      io.close
    else
      IO.for_fd(fd).close rescue nil # rubocop:disable Style/RescueModifier
    end
  end

  ForkSessionResult.new(session_id: forked_session_id)
end

.rename_session(session_id:, title:, directory: nil) ⇒ Object

Rename a session by appending a custom-title entry.

list_sessions reads the LAST custom-title from the file tail, so repeated calls are safe — the most recent wins.

Parameters:

  • session_id (String) —

    UUID of the session to rename

  • title (String) —

    New session title (whitespace stripped)

  • directory (String, nil) (defaults to: nil) —

    Project directory path

Raises:

  • (ArgumentError) —

    if session_id is invalid or title is empty

  • (Errno::ENOENT) —

    if the session file cannot be found



26
27
28
29
30
31
32
33
34
35
36
 
# File 'lib/claude_agent_sdk/session_mutations.rb', line 26

def rename_session(session_id:, title:, directory: nil)
  raise ArgumentError, "Invalid session_id: #{session_id}" unless session_id.match?(Sessions::UUID_RE)

  stripped = title.strip
  raise ArgumentError, 'title must be non-empty' if stripped.empty?

  data = "#{JSON.generate({ type: 'custom-title', customTitle: stripped, sessionId: session_id },
                          space_size: 0)}\n"

  append_to_session(session_id, data, directory)
end

.tag_session(session_id:, tag:, directory: nil) ⇒ Object

Tag a session. Pass nil to clear the tag.

Appends a type:‘tag’,tag:<tag>,sessionId:<id> JSONL entry. Tags are Unicode-sanitized before storing.

Parameters:

  • session_id (String) —

    UUID of the session to tag

  • tag (String, nil) —

    Tag string, or nil to clear

  • directory (String, nil) (defaults to: nil) —

    Project directory path

Raises:

  • (ArgumentError) —

    if session_id is invalid or tag is empty after sanitization

  • (Errno::ENOENT) —

    if the session file cannot be found



48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
 
# File 'lib/claude_agent_sdk/session_mutations.rb', line 48

def tag_session(session_id:, tag:, directory: nil)
  raise ArgumentError, "Invalid session_id: #{session_id}" unless session_id.match?(Sessions::UUID_RE)

  if tag
    sanitized = sanitize_unicode(tag).strip
    raise ArgumentError, 'tag must be non-empty (use nil to clear)' if sanitized.empty?

    tag = sanitized
  end

  data = "#{JSON.generate({ type: 'tag', tag: tag || '', sessionId: session_id },
                          space_size: 0)}\n"

  append_to_session(session_id, data, directory)
end