feat: allow assistant to work on unsaved jobs

[doc-han]

Description

This PR allows the AI assistant to work on unsaved jobs.

Closes #4417 #4412

Validation steps

New unsaved workflow

1. Generate a new workflow using AI, don't click "create" yet
2. enter one of the nodes and use the AI chat to write some job code even tho it's not save.
3. we expect it to work

Already saved workflow with new nodes

1. You have an already saved workflow but then you add a new node manually or via AI chat.
2. enter that unsaved node and then write some job code
3. we expect it to work

AI Usage

Please disclose whether you've used AI anywhere in this PR (it's cool, we just
want to know!):

• I have used Claude Code
• I have used another model
• I have not used AI

You can read more details in our
Responsible AI Policy

Pre-submission checklist

• I have performed an AI review of my code (we recommend using /review
  with Claude Code)
• I have implemented and tested all related authorization policies.
  (e.g., :owner, :admin, :editor, :viewer)
• I have updated the changelog.
• I have ticked a box in "AI usage" in this PR

[codecov]

Codecov Report

❌ Patch coverage is 96.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.34%. Comparing base (c7e5016) to head (58e9749).
⚠️ Report is 9 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/lightning_web/channels/ai_assistant_channel.ex	90.90%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4416      +/-   ##
==========================================
+ Coverage   89.26%   89.34%   +0.07%     
==========================================
  Files         425      425              
  Lines       20090    20128      +38     
==========================================
+ Hits        17933    17983      +50     
+ Misses       2157     2145      -12     

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[elias-ba]

Hey @doc-han this is a really nice little feature that will have a huge impact on the AI Assistant's UX. Thanks a lot dude. I have left a few questions (mainly for my own curiosity and learning). I could approve this as is, but I think you'll need to add a few tests to cover at least the new handle_unsaved_job_message path in the channel and the job_chat? / update_session_with_job_context logic in the message processor.

[josephjclark]

This is probably unrelated @doc-han but here's another issue in the same area:

• Edit an unsaved job
• Generate code with AI
• Close the AI Assistant
• The inspector freaks out and leaves you with this

[doc-han]

This is probably unrelated @doc-han but here's another issue in the same area:

• Edit an unsaved job
• Generate code with AI
• Close the AI Assistant
• The inspector freaks out and leaves you with this

noted and resolved.

[elias-ba]

Nicely done Commander Han ! ⚔️

[josephjclark]

What about those failing tests? Do they need fixing or can we merge?

[elias-ba]

Hey @josephjclark no failing tests but we could improve the coverage of the ai_assistant_channel.ex. Let me push a commit with one test that could do us good here.

[doc-han]

@elias-ba dealing with that

[doc-han]

@elias-ba codecov looking good now. thanks