fix: support associations without an id

[michaelst]

Problem

maybe_remove_from_association/4 dereferenced .id on every member of a loaded has_many:

Enum.filter(list, &(is_map(&1) && &1.id not in records_to_remove))

That raises a KeyError for join style schemas with a composite primary key and no id field. Worse, the filter runs even when records_to_remove is empty, so any sync message crashes a LiveView that has such an association loaded — unrelated inserts, updates, or deletes on some other table are enough.

Real crash from a LiveView watching a record whose child has a composite primary key:

** (KeyError) key :id not found in:

    %Dishbooks.Expenses.Schemas.BillItemLocation{
      __meta__: #Ecto.Schema.Metadata<:loaded, "bill_item_locations">,
      amount: Decimal.new("1200.00"),
      bill_item_id: "bli_01kxpdj8879rk6gh7eyjsvg2zr",
      location_id: "loc_01kw2phfp16vje31k3y3fvfar7",
      ...
    }

    (live_sync 0.1.11) lib/live_sync/socket.ex:211: anonymous fn/2 in LiveSync.Socket.maybe_remove_from_association/4
    (elixir 1.19.5) lib/enum.ex:4445: Enum.filter_list/2
    (live_sync 0.1.11) lib/live_sync/socket.ex:168: anonymous fn/6 in LiveSync.Socket.traverse_associations/3
    ...

Fix

Compare records with LiveSync.lookup_info/1 — the same lookup that already keys the updates map — instead of raw .id. Schemas with no Watch impl look up as nil and are never removed, which is the correct behavior for a child schema that isn't synced.

sync/4 had the same assumption baked in (record.__struct__ == schema and record.id == id) and would raise for any schema deriving Watch with a custom id: option, so it uses the lookup too.

Tests

New works with associations without an id reproduces the stack frame above, via a LiveSync.ExampleTag support schema with a composite primary key. Verified red before the fix, green after.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes

  • Improved live synchronization for associations whose records do not have a standalone ID.
  • Association items now remain correctly synchronized when parent records are updated or removed.

• New Features

  • Added support for displaying and synchronizing example tags associated through composite keys.

• Tests

  • Added coverage validating initial tag rendering and continued visibility after updates.
  • Expanded test setup for tag associations.

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ℹ️ Recent review info

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Configuration used: Organization UI

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• test/support/live_page.ex

---

📝 Walkthrough

Walkthrough

The change adds an ID-less ExampleTag association, uses lookup values for synchronization matching, renders tags, adds regression coverage, and updates the project version to 0.1.12.

Changes

ID-less association synchronization

Layer / File(s)	Summary
Composite-key association fixture test/support/example_tag.ex, test/support/example.ex, lib/test_helper.exs	Adds the composite-key LiveSync.ExampleTag schema, the example_tags association, and database setup and cleanup.
Lookup-based synchronization matching lib/live_sync/socket.ex	sync/4 and association removal compare records through LiveSync.lookup_info/1 instead of direct id fields.
Rendering and regression validation test/support/live_page.ex, lib/live_sync/socket_test.exs, lib/live_sync/replication_test.exs, mix.exs	Preloads and renders tags, verifies tag persistence after a parent update, cleans up the new table, and updates the project version.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Sequence Diagram(s)

sequenceDiagram
  participant Test
  participant LivePage
  participant LiveSync
  participant Database
  Test->>Database: Create ExampleTag
  LivePage->>Database: Preload example_tags
  LivePage->>Test: Render tag name
  Test->>LiveSync: Update parent Example
  LiveSync->>LiveSync: Compare lookup_info values
  LiveSync->>Test: Synchronize updated parent and tag

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🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: supporting associations without an id field.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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• Commit unit tests in branch fix-associations-without-id

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Actionable comments posted: 1

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Inline comments:
In `@test/support/live_page.ex`:
- Line 26: Update the preload list in sync/3 to include the :ignored association
alongside :parent, :children, and :example_tags, ensuring render/1 can safely
enumerate `@data.ignored` when it is not already loaded.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: 17959656-9051-43e9-b8ee-eca879c2093d

📥 Commits

Reviewing files that changed from the base of the PR and between cb8777b and e4ddabf.

📒 Files selected for processing (8)

• lib/live_sync/replication_test.exs
• lib/live_sync/socket.ex
• lib/live_sync/socket_test.exs
• lib/test_helper.exs
• mix.exs
• test/support/example.ex
• test/support/example_tag.ex
• test/support/live_page.ex