Port from nearai/ironclaw#2304: Telegram's 4096 character limit is
measured in UTF-16 code units, not Unicode codepoints. Characters
outside the Basic Multilingual Plane (emoji like 😀, CJK Extension B,
musical symbols) are surrogate pairs: 1 Python char but 2 UTF-16 units.
Previously, truncate_message() used Python's len() which counts
codepoints. This could produce chunks exceeding Telegram's actual limit
when messages contain many astral-plane characters.
Changes:
- Add utf16_len() helper and _prefix_within_utf16_limit() for
UTF-16-aware string measurement and truncation
- Add _custom_unit_to_cp() binary-search helper that maps a custom-unit
budget to the largest safe codepoint slice position
- Update truncate_message() to accept optional len_fn parameter
- Telegram adapter now passes len_fn=utf16_len when splitting messages
- Fix fallback truncation in Telegram error handler to use
_prefix_within_utf16_limit instead of codepoint slicing
- Update send_message_tool.py to use utf16_len for Telegram platform
- Add comprehensive tests: utf16_len, _prefix_within_utf16_limit,
truncate_message with len_fn (emoji splitting, content preservation,
code block handling)
- Update mock lambdas in reply_mode tests to accept **kw for len_fn
Add configurable reply-reference behavior for Discord, matching the
existing Telegram (TELEGRAM_REPLY_TO_MODE) and Mattermost
(MATTERMOST_REPLY_MODE) implementations.
Modes:
- 'off': never reply-reference the original message
- 'first': reply-reference on first chunk only (default, current behavior)
- 'all': reply-reference on every chunk
Set DISCORD_REPLY_TO_MODE=off in .env to disable reply-to messages.
Changes:
- gateway/config.py: parse DISCORD_REPLY_TO_MODE env var
- gateway/platforms/discord.py: read reply_to_mode from config, respect
it in send() — skip fetch_message entirely when 'off'
- hermes_cli/config.py: add to OPTIONAL_ENV_VARS for hermes setup
- 23 tests covering config, send behavior, env var override
- docs: discord.md env var table + environment-variables.md reference
Closes community request from Stuart on Discord.
