fix(editor): Position chat welcome message to center with base LLM models

[Cadiac]

Summary

Now that chat suggested prompts are out we (accidentally?) changed the layout also on base LLM chats, positioning the chat greeting to the top. This looks pretty empty, lets position it to the center instead.

Perhaps we'll add suggested prompts for base LLM chats too later, but as we don't have them now lets make this look slightly better.

Related Linear tickets, Github issues, and Community forum posts

https://linear.app/n8n/issue/CHA-154/bug-position-chat-greetings-text-to-the-middle

Review / Merge checklist

• PR title and summary are descriptive. (conventions)
• Docs updated or follow-up ticket created.
• Tests included.
• PR Labeled with release/backport (if the PR is an urgent fix that needs to be backported)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

[cubic-dev-ai]

cubic analysis

No issues found across 1 file

Linked issue analysis

Linked issue: CHA-154: Bug - Position chat greetings text to the middle

Status	Acceptance criteria	Notes
✅	Center the chat greetings prompt for base LLM chats (non-agent models).	Applied greetingsCentered class when not an agent model
✅	Keep agent models' greetings positioned at the top (do not center agent chats).	Introduced isAgentModel and isAgentNewSession layout class
✅	Only apply centering when showing the greeting for a new session.	ChatGreetings is rendered only when isNewSession (v-if)
✅	Add computed detection for agent vs base LLM models.	Added isAgentModel computed using selectedModel and isLlmProvider
✅	Add CSS rules to center the greetings (flex centering) and maintain agent spacing.	Added .greetingsCentered flex center and .isAgentNewSession padding-top

Architecture diagram

sequenceDiagram
    participant CV as ChatView (Vue Component)
    participant CS as ChatStore (State)
    participant CG as ChatGreetings (Sub-component)

    Note over CV,CS: Runtime Layout Initialization
    CV->>CS: Access selectedModel property
    CS-->>CV: Return ChatModelDto

    CV->>CV: NEW: Compute isAgentModel (Boolean)
    Note right of CV: Checks if provider is NOT a standard LLM

    alt isNewSession is TRUE
        CV->>CV: CHANGED: Determine Layout Class
        
        alt isAgentModel is TRUE
            CV->>CV: Apply .isAgentNewSession (Padding-top)
        else isAgentModel is FALSE (Base LLM)
            CV->>CV: NEW: Apply .greetingsCentered (Flex-center)
        end

        CV->>CG: Render Greetings Component
        Note over CV,CG: NEW: Inject .greetingsCentered class via props
    else isExistingSession
        CV->>CV: Apply .isExistingSession (Standard layout)
    end

    Note over CV: Browser applies CSS Flexbox rules based on dynamic classes

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[codecov]

Bundle Report

Changes will increase total bundle size by 607 bytes (0.0%) ⬆️. This is within the configured threshold ✅

Detailed changes

Bundle name	Size	Change
editor-ui-esm	42.4MB	607 bytes (0.0%) ⬆️

Affected Assets, Files, and Routes:

view changes for bundle: editor-ui-esm

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
assets/worker-*.js	-2.91MB	13.37kB	-99.54%
assets/worker-*.js	2.91MB	2.92MB	21725.55% ⚠️
assets/ChatView-*.js	438 bytes	675.22kB	0.06%
assets/ChatView-*.css	169 bytes	94.22kB	0.18%

Files in assets/ChatView-*.js:

• ./src/features/ai/chatHub/ChatView.vue → Total Size: 309 bytes

[autologie]

Perhaps we'll add suggested prompts for base LLM chats too later

Maybe we haven't settled yet, but I believe this is the plan
https://www.figma.com/design/RVJgBrL0fXTCvreYqfWAlL/ChatHub-Scratchpad-2026?node-id=245-2132&t=JEnFftR79LH9v78l-0