fix(slack): markdown rendering fidelity — fences, entities, bold, links + opt-in markdown blocks - #70191
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…text
format_message unescapes already-escaped input before re-escaping, so that
pre-escaped text doesn't get double-escaped. That unescape was three
sequential str.replace calls, which re-scan each other's output:
"&lt;" --(& -> &)--> "<" --(< -> <)--> "<"
The & produced by the first replace pairs with the following "lt;" and
decodes a second time. "&lt;" is the wire form of the literal text
"<", so the text is silently destroyed: Slack receives "<" and renders
"<". Anyone writing about HTML or markup ("&lt;b&gt;" -> "<b>")
loses their literal text, with no error.
re.sub scans left-to-right and never re-scans its own replacements, so a
single pass fixes it. The escape pass on the next line is left untouched --
it is correctly ordered (& first, so the &s it inserts aren't re-escaped).
Only the double-decode cases change; every other input is byte-identical
before and after. This is the same round-trip invariant the neighbouring
test_pre_escaped_{ampersand,lt,gt}_not_double_escaped tests already assert,
extended to the case they miss. Affects the plain mrkdwn path (send,
edit_message) and Block Kit sections, which route section text through
format_message.
Slack's mrkdwn does not strip the optional language tag from fenced code blocks like GitHub-flavored markdown does — it renders ```text\nfoo\n``` as a code block whose literal first line is "text". The agent emitted ```text fences around raw command output, which surfaced "text" as the first line of every such block. Drop the tag from the opening fence in format_message() before stashing the block behind a placeholder. Stripping only fires for a genuine opening fence — a ``` at the start of a line, tagged with a single token (no spaces or backticks) — and the original line ending is preserved. The fence-protection regex deliberately matches loosely, so a mid-line ``` (e.g. an inline ```span``` wrapping across a newline) can be grouped as an "opening fence" whose first line is real content; differential fuzzing against the pre-change formatter (40k generated messages) confirms the only behavioral delta is the tag strip itself. The Block Kit renderer is unaffected: render_blocks() intercepts fences itself before mrkdwn_fn is applied, so this only changes the mrkdwn surfaces that still go through format_message() — the plain-text fallback field (notifications, search indexing, accessibility), slash-command ephemeral replies, and standalone cron delivery. Originally written against gateway/platforms/slack.py; ported to plugins/platforms/slack/adapter.py after the adapter migration in 5600105. Manually verified against a live Slack workspace (pre-migration adapter; the ```text case strips identically) — code blocks no longer carry a literal "text" first line.
…d chars Slack's mrkdwn parser can fail to recognize the closing * of a bold span when it is immediately preceded by a non-word character (), ], }, ., :, em-dash, ...), mis-rendering the span and in reported cases truncating the rest of the message. Insert a zero-width space (U+200B) between the last character and the closing * whenever the last character is not alphanumeric or underscore. Reapplied from #35144 by @gonzalofrancoceballos — the original patched gateway/platforms/slack.py, which was migrated to plugins/platforms/slack/adapter.py in the plugin migration.
…e block B1: When reasoning content contains ``` e.g. model quoting code in its thinking, wrapping it in an outer ``` for display causes the inner fence to break the outer block. Adds escape_code_fences_for_display() in gateway/stream_consumer.py, called from gateway/run.py before wrapping reasoning in the outer ``` display block.
- A/B/C: truncate_message with reasoning format, carry_lang, multiple blocks - D: last-chunk early-break gap - E: _filter_and_accumulate preserves triple-backtick outside think blocks - F: _split_text_chunks has no fence tracking - G: reasoning truncation (short pass-through, long gap) - H: stream consumer accumulator has no fence state - I: fix stub - J: edit path bypasses truncate_message entirely - K: overflow split first chunk via edit path - L: fallback final + split_text_chunks noop Four gaps identified: G1: truncate_message last-chunk early-break path G2: streaming edit path bypasses truncate_message G3: overflow split first chunk via edit path G4: split_text_chunks + truncate_message no-op
Adds `ensure_closed_code_fences()` helper to detect text with an odd count of triple-backtick markers (indicating an unclosed code block) and append a closing fence. Applies the fix to all four identified gap paths: G1: truncate_message early-break path for final chunk G2: _send_or_edit streaming edit path (most commonly hit) G3: overflow split first chunk (covered by G2's fix) G4: _send_fallback_final fallback send path Closes: #TBD
ensure_closed_code_fences previously only handled triple-backtick (```) code-block fences. Single backtick (`) inline-code spans have the same problem: an orphaned opening backtick causes the remainder of the message to render as inline code on Discord and other platforms. After balancing triple-backtick fences, strip complete ```...``` regions and count remaining standalone backtick markers. If odd, append a closing backtick. Same trade-off as the triple-backtick fix: a stray closing backtick may create a brief empty inline-code span, which is far less harmful than the rest of the message being inline code.
Slack mrkdwn has no table syntax — GFM pipe tables render as literal-pipe noise with a raw |---|---| separator row. Wrap detected tables in ``` fences so they render as monospace preformatted text, and pad cells to per-column max display width (East-Asian Wide / Full-width chars counted as 2 columns) so columns stay aligned even with CJK content. Tables already inside fenced code blocks are left untouched, and the emitted fences carry no language tag so they compose with the lang-tag-strip pass. This covers the plain-mrkdwn text path; the opt-in rich_blocks path already renders native Block Kit table blocks. Reapplied from #16648 by @kylezh — the original patched gateway/platforms/slack.py, which was migrated to plugins/platforms/slack/adapter.py in the plugin migration. Fixes the non-rich_blocks table path described in #8552.
…arkdown Slack's Block Kit `markdown` block accepts standard markdown (tables, headers, task lists, fenced code with syntax highlighting, links) and lets Slack translate it natively — eliminating the lossy markdown→mrkdwn conversion for the rendered layout. Enable via platforms.slack.extra.markdown_blocks. Safety rails added on top of the original design: * opt-in (default off) — Slack documents the block for 'apps that use platform AI features' and does not guarantee availability across all app types / surfaces, so unconditional adoption is not safe yet * the mrkdwn-converted text field is ALWAYS kept as the notification/search/accessibility fallback * content over Slack's 12k cumulative markdown-block cap declines to the rich_blocks renderer / plain text path * the existing block-rejection retry (invalid_blocks / msg_too_long / too_many_blocks) re-sends the plain mrkdwn payload, so an unsupported surface degrades gracefully instead of dropping the message * when both modes are enabled, markdown_blocks is preferred over the local rich_blocks renderer; rich_blocks remains the fallback Adapted from #8554 by @shivasymbl — the original patched the deleted gateway/platforms/slack.py and switched unconditionally; reimplemented against the plugin adapter's _maybe_blocks/sanitize_blocks pipeline. Fixes #8552.
Widen #48476's fence guarantees to the two splitters that still emitted fence-broken chunks: * GatewayStreamConsumer._split_text_chunks (fallback final send): close the orphaned ``` at each chunk boundary and reopen it — with the original language tag — on the next chunk, mirroring BasePlatformAdapter.truncate_message's contract. Headroom is reserved so balanced chunks stay within the platform limit. * Slack block_kit._split_text (3000-char section chunking): same close/reopen balancing for mrkdwn section text carrying fences. With these, every chunk boundary — non-streaming send (truncate_message), streaming overflow (_truncate_for_stream via adapter.truncate_message per #45938), fallback final (_split_text_chunks), final-send balance (ensure_closed_code_fences), and Block Kit section splits — delivers fence-balanced chunks. Regression tests probe each path with fenced fixtures, assert per-chunk balance, limit compliance, language-tag reopening, and prose passthrough.
shivasymbl, z23, Skywind5487, 2001Y, gonzalofrancoceballos, kylezh. briandevans' noreply mapping already present; mzkarami's mapping file shipped inside #66204's own commit. Also fixes the TestFormatMessageTableIntegration fixture to match PlatformConfig's current signature (no 'name' kwarg).
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Summary
Agent output renders faithfully in Slack: code fences close on every chunk boundary, HTML entities decode exactly once, bold edge cases don't corrupt, language tags don't leak, links don't duplicate — plus an opt-in
markdown_blocksmode using Slack's native markdown block type.Fixes #8552.
Changes
markdown_blocksconfig mode in_maybe_blocks(fix(slack): use Block Kit markdown block type instead of legacy mrkdwn #8554, adapted — mrkdwn remains the default and fallback).&lt;double-decoded on main); ZWSP bold guard (fix(slack): broaden bold-text zero-width-space guard to all non-word chars #35144 — premise corrected: no prior guard existed, this ADDS it); language-tag stripping with line-start guard (fix(gateway): strip language tag from Slack fenced code blocks #21085);ensure_closed_code_fenceson all send paths + final-chunk fix (fix: close orphaned code fences on all send paths #48476); triple-backtick escaping in code-style reasoning (fix: escape triple-backtick inside reasoning before wrapping in outer code block #48477); rich-text link dedup (fix(slack): avoid duplicating rich-text link messages #66204); editable overflow stream chunks (fix(gateway): keep overflow stream chunks editable #45938).Credits
Salvaged with authorship preserved: #8554 (@shivasymbl), #64748 (@briandevans), #21085 (@z23), #35144 (@gonzalofrancoceballos), #48476 + #48477 (@Skywind5487), #66204 (@mzkarami), #45938 (@2001Y).
Supersedes #15854, #35802 (table handling covered by main's rich_blocks machinery).
Validation
tests/gateway/ -q -k slackInfographic