fix(slack-bot): ensure PR/MR URLs surface in Slack replies

[kilo-code-bot]

Summary

Users reported that PR/MR URLs created by the cloud agent never appear in Slack bot replies. Investigation found three independent root causes:

• Legacy bot missing prompt instruction: The legacy Slack bot (src/lib/slack-bot.ts) did not append "Open a pull request and return the PR URL" to the cloud agent prompt for code mode sessions. The System 2 bot (Pound) already did this at src/lib/bot/tools/spawn-cloud-agent-session.ts:87-93, but the legacy bot only appended the PR signature — not the URL return instruction.
• No explicit LLM instruction to relay URLs: Neither bot's system prompt nor tool description explicitly told the outer LLM to extract PR/MR URLs from tool results and include them in the user-facing reply. The tool description in the legacy bot only said "Provide exactly one of githubRepo or gitlabProject" with no post-call guidance. The System 2 bot's tool description already had this instruction but the system prompt did not reinforce it.
• Slack section block 3000-char truncation: The legacy webhook route (src/app/slack/webhook/route.ts:219-232) placed the entire formatted response in a single section block. Slack's API silently truncates section.text at 3000 characters. Cloud agent responses often exceed this, with the PR URL appearing near the end — exactly where it gets cut off.

Fixes applied:

1. Legacy bot now appends "Open a PR/MR and return the URL" to the cloud agent prompt in code mode (matching System 2 behavior)
2. Both bots' system prompts now include a "Sharing results" section instructing the LLM to extract and relay PR/MR URLs
3. Legacy tool description updated to include post-call URL relay instruction
4. Legacy webhook now splits long responses into multiple section blocks to stay within Slack's 3000-char limit

Verification

• pnpm typecheck — passed
• pnpm format:check — passed (via pre-push hook)
• ESLint — passed (via pre-push hook)
• Manual review of all three changed files for correctness

Visual Changes

N/A

Reviewer Notes

• The System 2 bot (Pound, src/lib/bot/run.ts) was already better instrumented than the legacy bot — its tool description at line 152 already said "check the result for a PR/MR URL and share it with the user." The system prompt section added here reinforces this at a different layer.
• The toSectionBlocks function in the webhook route splits on newline boundaries to avoid breaking URLs mid-character. Falls back to hard-split if no newline is found within the limit.
• The 3000-char section block limit is a known Slack API constraint. The text field outside blocks is preserved as-is (40k char limit) and serves as fallback for clients that don't render blocks.

[kilo-code-bot]

WARNING: Hard-split path drops one character

When no newline exists within the limit, splitAt is set to charLimit, but this line still advances by + 1. That skips the character at the split boundary, so long single-line responses lose one character per block and can still break PR/MR URLs or code blocks.

Suggested change

	remaining = remaining.slice(splitAt + 1);
	remaining = remaining.slice(remaining[splitAt] === '\n' ? splitAt + 1 : splitAt);

[kilo-code-bot]

Code Review Summary

Status: 1 Issue Found | Recommendation: Address before merge

Overview

Severity	Count
CRITICAL	0
WARNING	1
SUGGESTION	0

Issue Details (click to expand)

WARNING

File	Line	Issue
src/app/slack/webhook/route.ts	71	The hard-split fallback drops the character at the split boundary, so long single-line responses can still corrupt PR/MR URLs.

Fix these issues in Kilo Cloud

Other Observations (not in diff)

N/A

Files Reviewed (3 files)

• src/app/slack/webhook/route.ts - 1 issue
• src/lib/bot/run.ts - 0 issues
• src/lib/slack-bot.ts - 0 issues

---

_{Reviewed by gpt-5.4-20260305 · 222,130 tokens}