fix(camera): report the camera's negotiation role, not the client's

[cleithner-comcast]

The ep/webrtc negotiationRole resource is the camera's data model, so it now reports the CAMERA's WebRTC role — offerer when the camera generates the offer (SolicitOffer flow), answerer when it answers the client's offer (ProvideOffer flow) — instead of the role the client must take. An intrinsic cameraIsOfferer() predicate drives both the reported role and the (unchanged) Matter flow selection. The reference app inverts the reported value to choose its own role.

The Matter signaling sequence is unchanged. Driver, reference app, the camera unit test (adds NegotiationRoleReportsCameraRole), and the webrtc-signaling- endpoint / camera-stream-reference-command specs are updated to the camera perspective; archives the openspec change.

[Copilot]

Pull request overview

This PR inverts the ep/webrtc/r/negotiationRole contract so it reports the camera’s WebRTC negotiation role (offerer/answerer) rather than the client’s, and updates the in-tree consumer (reference app), SBMD driver logic, specs, and unit tests to match.

Changes:

• SBMD driver: introduce a cameraIsOfferer() predicate and use it to (a) report the camera’s role via readNegotiationRole and (b) keep executeLocalSdp’s Matter flow selection unchanged.
• Reference app: invert the reported camera role to derive the client’s webrtcbin role.
• OpenSpec + tests: update specs to the camera perspective and add a unit test asserting the updated role mapping.

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
reference/src/cameraDeviceSession.h	Clarifies GetRole() returns the camera’s role (client uses opposite).
reference/src/cameraDeviceSession.c	Updates role caching/read commentary to camera-perspective semantics.
reference/src/cameraCategory.c	Inverts negotiation role interpretation to derive the client’s role.
core/deviceDrivers/matter/sbmd/specs/camera.sbmd.js	Implements camera-perspective role reporting via cameraIsOfferer(); keeps signaling flow selection aligned.
core/test/src/SbmdCameraWebrtcTest.cpp	Adds NegotiationRoleReportsCameraRole and a helper to invoke read handlers with supplements.
openspec/specs/webrtc-signaling-endpoint/spec.md	Updates endpoint contract: negotiationRole now reports the camera’s role and defaults accordingly.
openspec/specs/camera-stream-reference-command/spec.md	Updates reference-app command contract to invert the camera-reported role.
openspec/changes/archive/2026-08-03-negotiation-role-camera-perspective/tasks.md	Archives implementation checklist for the contract inversion.
openspec/changes/archive/2026-08-03-negotiation-role-camera-perspective/specs/webrtc-signaling-endpoint/spec.md	Archived delta spec reflecting the updated negotiationRole requirement.
openspec/changes/archive/2026-08-03-negotiation-role-camera-perspective/specs/camera-stream-reference-command/spec.md	Archived delta spec reflecting reference-app inversion behavior.
openspec/changes/archive/2026-08-03-negotiation-role-camera-perspective/proposal.md	Archived proposal describing the breaking contract inversion and scope.
openspec/changes/archive/2026-08-03-negotiation-role-camera-perspective/design.md	Archived design describing predicate-based refactor and unchanged Matter flow selection.
openspec/changes/archive/2026-08-03-negotiation-role-camera-perspective/.openspec.yaml	Archives change metadata.

[tleacmcsa]

I'm good with it after addressing copilot's comments.

[Copilot]

Pull request overview

Copilot reviewed 13 out of 13 changed files in this pull request and generated no new comments.

Suppressed comments (1)

openspec/specs/webrtc-signaling-endpoint/spec.md:14

• The Purpose section still describes negotiationRole as telling the client whether it is the offerer/answerer, which contradicts the updated contract below (the table row now says it reports the camera’s role and the client adopts the opposite). Updating the Purpose text avoids ambiguity for spec readers.

| `localSdp` | `function` | execute | Client posts its local SDP (offer or answer) to drive signaling |
| `negotiationRole` | `string` | [read] | Reports the **camera's** negotiation role (`offerer` or `answerer`); the client adopts the opposite role |
| `remoteSdp` | `string` | [] (events only) | Delivers the camera's remote SDP (offer or answer) to client |