fix: preserve multi-line text in slash command params

[prathamesh04]

Proposed changes

Add the s (dotall) flag to the slash command parse regex so that multi-line input is fully captured instead of being truncated at the first newline.

Before:

const match = msg.match(/^\/([^\s]+)(.*)/);

After:

const match = msg.match(/^\/([^\s]+)(.*)/s);

The s flag makes . match newline characters (\n), allowing the regex to capture the full multi-line text that follows the slash command.

Why this change?

When a user types a slash command with multi-line text (using Shift+Enter), the client silently discards everything after the first line break. For example:

/msg @alice
don't forget the standup

Only @alice was being sent to the server - the second line was lost without any warning.

The server-side parseParameters function already handles multi-line text correctly, so this fix aligns the client behavior with what the server already supports.

How to test

1. Start the Rocket.Chat dev server (yarn dsv)
2. Open the web client at http://localhost:3000
3. Type a slash command, e.g., /msg @username
4. Press Shift+Enter to add a second line
5. Type additional text on the second line
6. Send the message
7. Verify the full multi-line text reaches the command handler

Related issue

Closes #41324

Summary by CodeRabbit

• Bug Fixes
  • Slash commands now correctly support parameters that span multiple lines.

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[coderabbitai]

Walkthrough

The client slash-command parser now uses dotAll matching so command parameters can include newline characters instead of stopping at the first line break.

Changes

Slash-command parsing

Layer / File(s)	Summary
Capture multiline command parameters apps/meteor/client/lib/chats/flows/processSlashCommand.ts	The parse regex enables dotAll mode, allowing the params capture to span line breaks.

Estimated code review effort: 1 (Trivial) | ~3 minutes

Suggested labels: type: bug

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the main change: preserving multi-line slash command parameters.
Linked Issues check	✅ Passed	The regex dotAll change matches the issue by preserving text after line breaks for slash commands.
Out of Scope Changes check	✅ Passed	The PR is narrowly scoped to the slash-command parsing fix with no unrelated code changes.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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[coderabbitai]

🧹 Nitpick comments (1)

apps/meteor/client/lib/chats/flows/processSlashCommand.ts (1)

13-13: 🎯 Functional Correctness | 🔵 Trivial | ⚡ Quick win

Add a regression test for newline preservation.

Cover input such as /command first line\nsecond line and assert that params remains first line\nsecond line. This protects the behavior introduced here from future regex changes.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@apps/meteor/client/lib/chats/flows/processSlashCommand.ts` at line 13, Add a
regression test for the slash-command parsing flow around the message-matching
logic, using input with a newline such as `/command first line\nsecond line`;
assert that the extracted params preserve the leading space and newline exactly
as ` first line\nsecond line`.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@apps/meteor/client/lib/chats/flows/processSlashCommand.ts`:
- Line 13: Add a regression test for the slash-command parsing flow around the
message-matching logic, using input with a newline such as `/command first
line\nsecond line`; assert that the extracted params preserve the leading space
and newline exactly as ` first line\nsecond line`.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 112dbeb1-cb0a-4baf-ba67-c3a6df98a5a0

📥 Commits

Reviewing files that changed from the base of the PR and between edbaeef and ac7a49d.

📒 Files selected for processing (1)

• apps/meteor/client/lib/chats/flows/processSlashCommand.ts

📜 Review details

⏰ Context from checks skipped due to timeout. (2)

• GitHub Check: CodeRabbit
• GitHub Check: cubic · AI code reviewer

🧰 Additional context used

📓 Path-based instructions (1)

**/*.{ts,tsx,js}

📄 CodeRabbit inference engine (.cursor/rules/playwright.mdc)

**/*.{ts,tsx,js}: Write concise, technical TypeScript/JavaScript with accurate typing in Playwright tests
Avoid code comments in the implementation

Files:

• apps/meteor/client/lib/chats/flows/processSlashCommand.ts

🧠 Learnings (5)

📚 Learning: 2026-02-10T16:32:42.586Z

Learnt from: tassoevan
Repo: RocketChat/Rocket.Chat PR: 38528
File: apps/meteor/client/startup/roles.ts:14-14
Timestamp: 2026-02-10T16:32:42.586Z
Learning: In Rocket.Chat's Meteor client code, DDP streams use EJSON and Date fields arrive as Date objects; do not manually construct new Date() in stream handlers (for example, in sdk.stream()). Only REST API responses return plain JSON where dates are strings, so implement explicit conversion there if needed. Apply this guidance to all TypeScript files under apps/meteor/client to ensure consistent date handling in DDP streams and REST responses.

Applied to files:

• apps/meteor/client/lib/chats/flows/processSlashCommand.ts

📚 Learning: 2026-05-11T20:30:35.265Z

Learnt from: tassoevan
Repo: RocketChat/Rocket.Chat PR: 40480
File: apps/meteor/client/meteor/startup/accounts.ts:59-61
Timestamp: 2026-05-11T20:30:35.265Z
Learning: In Rocket.Chat’s Meteor client code, when calling `dispatchToastMessage` with `{ type: 'error' }`, pass the raw caught error object as `message` without manual normalization. `dispatchToastMessage` is designed to accept `message: unknown` for error toasts, so avoid converting errors to strings (e.g., `String(error)`) or extracting `error.message` before passing them.

Applied to files:

• apps/meteor/client/lib/chats/flows/processSlashCommand.ts

📚 Learning: 2026-02-26T19:25:44.063Z

Learnt from: gabriellsh
Repo: RocketChat/Rocket.Chat PR: 38778
File: packages/ui-voip/src/providers/useMediaSession.ts:192-192
Timestamp: 2026-02-26T19:25:44.063Z
Learning: In the Rocket.Chat repository, do not reference Biome lint rules in code review feedback. Biome is not used even if biome.json exists; only reference Biome rules if there is explicit, project-wide usage documented. For TypeScript files, review lint implications without Biome guidance unless the project enables Biome rules.

Applied to files:

• apps/meteor/client/lib/chats/flows/processSlashCommand.ts

📚 Learning: 2026-02-26T19:25:44.063Z

Learnt from: gabriellsh
Repo: RocketChat/Rocket.Chat PR: 38778
File: packages/ui-voip/src/providers/useMediaSession.ts:192-192
Timestamp: 2026-02-26T19:25:44.063Z
Learning: In this repository (RocketChat/Rocket.Chat), Biome lint rules are not used even if a biome.json exists. When reviewing TypeScript files (e.g., packages/ui-voip/src/providers/useMediaSession.ts), ensure lint suggestions do not reference Biome-specific rules. Rely on general ESLint/TypeScript lint rules and project conventions instead.

Applied to files:

• apps/meteor/client/lib/chats/flows/processSlashCommand.ts

📚 Learning: 2026-05-06T12:21:44.083Z

Learnt from: juliajforesti
Repo: RocketChat/Rocket.Chat PR: 40256
File: apps/meteor/client/components/CreateDiscussion/CreateDiscussion.tsx:121-149
Timestamp: 2026-05-06T12:21:44.083Z
Learning: Field wrappers in rocket.chat/fuselage-forms (Field, FieldLabel, FieldRow, FieldError, FieldHint) auto-create htmlFor/id associations, aria-describedby, and role="alert" for errors. Do not manually set htmlFor, id, aria-describedby, or role attributes when using these wrappers. This automatic wiring does not apply to plain rocket.chat/fuselage components, which require explicit ID wiring per the accessibility docs. In code reviews, prefer using fuselage-forms wrappers for form fields and verify there is no unnecessary manual ID/aria wiring in files that use these wrappers. If a component uses plain fuselage components, ensure proper id wiring as per docs.

Applied to files:

• apps/meteor/client/lib/chats/flows/processSlashCommand.ts

[cubic-dev-ai]

No issues found across 1 file

_{Re-trigger cubic}

[prathamesh04]

This PR is ready for review — @RocketChat/backend could you take a look?

[prathamesh04]

Hi @julio-rocketchat, could you please review this when you get a chance? Thanks!