Add Route nodes and HANDLES edges for DRF ViewSet actions

[muskiteer]

What does this PR do?

This PR adds support for indexing Django REST Framework ViewSet actions decorated with @action by emitting Route nodes and Route-[:HANDLES]->Method relationships.

Previously, DRF action methods were indexed only as Method nodes, which meant endpoint inventory and endpoint-to-handler mapping were incomplete for projects using DRF routers.

Changes

• Emit Route nodes for DRF @action methods.
• Populate route metadata (HTTP method, path, source, and file path where available).
• Create Route-[:HANDLES]->Method relationships linking routes to their corresponding handler methods.
• Preserve existing Method extraction.

Verification

Reproduced using a minimal Django REST Framework project:

class CustomerTaskAdminViewSet(ViewSet):
    @action(detail=True, methods=["post"])
    def approve_draft_with_charge(self, request, pk=None):
        ...

Before:

• Method node was present.
• No Route nodes were emitted.
• No Route-[:HANDLES]->Method relationships existed.

After:

• Route node is emitted.
• Route-[:HANDLES]->Method relationship is created.
• Route metadata is available for the action.

Checklist

• Every commit is signed off (git commit -s) — required, CI rejects unsigned commits (DCO, see CONTRIBUTING.md)
• Tests pass locally (make -f Makefile.cbm test)
• Lint passes (make -f Makefile.cbm lint-ci)
• New behavior is covered by a test (reproduce-first for bug fixes)

Fixes #603

[muskiteer]

Hi @DeusData,
I've opened a PR for the DRF ViewSet route extraction changes.

While testing locally, I ran into some issues with the test and lint targets. From what I could tell, these didn't appear to be directly related to the changes in this PR, but please let me know if I missed something.

I'd really appreciate any feedback or suggested changes. Happy to update the PR if needed.

Thanks

[DeusData]

Huge thanks for opening this PR and for the work you put into it.

The maintainer shop is currently full, so this may sit for a bit before it gets a proper review. We will come back to this as soon as possible with real feedback; I wanted to make sure it did not sit unacknowledged in the meantime.

[muskiteer]

@DeusData Thanks for the msg.
I am actually still working on this so take your time
Thanks

[DeusData]

Thank you @muskiteer — the DRF ViewSet @action extractor is genuinely useful work, and #603 was a real, previously-unhandled gap (no @action handling existed on main). I've verified the extractor logic is sound and the reproduce-first test is a valid guard.

I'm landing it as a focused distillation in #746 (024c0c5), co-authored with you, rather than merging this PR directly. The reason: alongside the extractor, this PR also reverses the HANDLES edge direction project-wide (handler→Route → Route→handler) across every framework (FastAPI/Flask/Express/Gin/gRPC/SvelteKit/…). That change is:

• Not needed for the fix — the added test counts HANDLES by type (direction-agnostic), and the existing Phase 2a pipeline already emits the edge, so the extractor alone closes Django REST Framework ViewSet routes miss HANDLES mappings #603 and greens the test; and
• A latent regression — pass_cross_repo.c's find_route_handler resolves a route's handler via WHERE e.target_id = <route> AND e.type='HANDLES' (i.e. it relies on handler→Route) and isn't updated in this PR, so after the flip, cross-repo route→handler resolution would silently return 0. No test catches it because the edge-count checks are direction-agnostic.

So the distilled PR keeps your extractor, drops the direction flip, preserves the documented handler→Route convention, and adds your test as the reproduce-first guard. Full credit to you as co-author. If the team ever wants Route→handler as the canonical direction, that's a deliberate, separate change that must update every consumer (pass_cross_repo.c, the schema, and the docs) together.

Really appreciate the contribution — the DRF support ships in the next release. 🙏