fix: parse and apply custom targeting from product forms to GAM line items

[bokelley]

Summary

Fixes the complete end-to-end flow for custom targeting configuration on products, ensuring targeting configured in the UI is properly applied to GAM line items.

Problem

The targeting selector widget was working (loading keys and values), but the custom targeting wasn't actually being applied to GAM line items because:

1. Product creation/edit ignored the form field: The targeting_template form field from the widget was never parsed - it was hardcoded to {}
2. Schema mismatch: Widget stores data in targeting_template.key_value_pairs, but GAM adapter reads from implementation_config.custom_targeting_keys

Solution

1. Parse targeting_template from form data (both add and edit)

Before:

"targeting_template": {},  # ❌ Hardcoded empty dict

After:

targeting_template_json = form_data.get("targeting_template", "{}")
targeting_template = json.loads(targeting_template_json) if targeting_template_json else {}

2. Copy key-value pairs to GAM implementation config

# If targeting template has key_value_pairs, copy to implementation_config for GAM
if targeting_template.get("key_value_pairs"):
    if "custom_targeting_keys" not in base_config:
        base_config["custom_targeting_keys"] = {}
    # Merge key-value pairs into implementation_config for GAM adapter
    base_config["custom_targeting_keys"].update(targeting_template["key_value_pairs"])

3. Persist both fields

product.targeting_template = targeting_template
product.implementation_config = base_config
attributes.flag_modified(product, "targeting_template")
attributes.flag_modified(product, "implementation_config")

Data Flow

User selects targeting in UI widget
  ↓
Widget stores in targeting_template.key_value_pairs
  ↓
Backend parses form data (THIS PR)
  ↓
Copies to implementation_config.custom_targeting_keys
  ↓
GAM adapter reads custom_targeting_keys
  ↓
Applied to GAM line item targeting

Test plan

• Load product add page
• Select custom targeting keys and values
• Submit form and verify targeting_template is saved
• Verify implementation_config.custom_targeting_keys is populated
• Edit existing product with targeting
• Verify changes are persisted
• Create media buy with product
• Verify GAM line item has custom targeting applied
• All tests pass (861 unit, 32 integration, 28 integration_v2)

Related PRs

• PR Optimize vertical spacing in targeting keys list #684: Fixed targeting browser compact spacing
• PR fix: targeting keys errors in browser and product pages #685: Fixed targeting keys loading in browser and product pages

This PR completes the targeting integration by connecting the UI to the GAM adapter.

🤖 Generated with Claude Code