Resolve profiles through built-in backends

docs/internal/runner.md

@@ -17,10 +17,11 @@ and override semantics consumed by the runner.
 ## Collaborators
 
 `Runner` coordinates narrow internal interfaces for prompt definitions,
-profiles, artifacts, rendering, model generation, and validation. Schema
-documents are loaded through the validator's optional schema-loader interface.
-An output repairer can be injected internally, but the ordinary runner
-constructor does not enable one.
+profiles, backend resolution, artifacts, rendering, model generation, and
+validation. The root engine supplies an immutable built-in backend registry.
+Schema documents are loaded through the validator's optional schema-loader
+interface. An output repairer can be injected internally, but the ordinary
+runner constructor does not enable one.
 
 Each invocation carries its state in request, prepared-run, and result values.
 The runner has no durable run or session store.
@@ -32,20 +33,25 @@ The runner has no durable run or session store.
 1. validate the prompt selection and load the prompt definition;
 2. hash the loaded definition;
 3. select the request profile or the prompt's default profile;
-4. resolve application-neutral defaults, profile values, and explicit request
-   overrides in that order;
-5. validate endpoint, model, numeric overrides, and credential requirements;
-6. resolve the output contract and load a structured-output schema when
+4. resolve the profile's backend ID, when present;
+5. resolve application-neutral defaults, backend defaults, profile values,
+   and explicit request overrides in that order;
+6. validate endpoint, model, numeric overrides, and credential requirements;
+7. resolve the output contract and load a structured-output schema when
    required;
-7. load and hash input artifacts;
-8. render and hash the prompt; and
-9. return the effective settings, source identities, messages, hashes, and
+8. load and hash input artifacts;
+9. render and hash the prompt; and
+10. return the effective settings, source identities, messages, hashes, and
    preparation timing.
 
 Pointer-based numeric overrides preserve an explicit zero. Invalid negative or
-out-of-range values fail as invalid requests. A direct API key takes
-precedence over environment lookup for execution; secret values remain
-excluded from serialized metadata.
+out-of-range values fail as invalid requests. Endpoint overrides do not change
+the selected backend identity. Non-empty extra-parameter maps replace whole
+lower-precedence maps. A direct API key takes precedence over environment
+lookup; otherwise request, profile, and backend environment-variable names
+apply in that order. A profile requiring a direct key clears an inherited
+backend environment name unless the request supplies its own name. Secret
+values remain excluded from serialized metadata.
 
 ## Run Flow
 
@@ -60,8 +66,10 @@ target, validation errors, prior output, and structured-output specification.
 This capability remains internal and is not a public option.
 
 A successful result includes the output artifact and raw output, validation
-state, prompt and rendered-prompt hashes, selected profile, effective settings,
-input hashes, token usage, a generated run identifier, and UTC timing.
+state, prompt and rendered-prompt hashes, selected profile and backend,
+effective settings, input hashes, token usage, a generated run identifier, and
+UTC timing. The same effective target, including backend identity, reaches
+generation and any repair attempt.
 
 ## Failure Categories
 
@@ -71,13 +79,16 @@ validation failures. Wrapping preserves the package identities mapped by the
 public facade and retains collaborator identities where they are part of the
 internal contract. Context cancellation propagates through the invoked
 collaborator and is classified by the owning operation.
+An unknown selected backend, or a selected backend with no configured resolver,
+is classified as a profile-load failure.
 
 ## Test Ownership And Changes
 
 The [runner tests](../../internal/usecase/runner_test.go) own preparation order,
 selection and override precedence, schema-before-generation behavior, hashing,
-generation and validation outcomes, bounded repair, credentials and redaction,
-error categories, artifact metadata, usage, and timing.
+generation and validation outcomes, backend propagation, bounded repair,
+credentials and redaction, error categories, artifact metadata, usage, and
+timing.
 
 Changes to orchestration should continue to use the existing package
 interfaces, keep request state local to an invocation, and preserve `Run`'s use

docs/internal/sources.md

@@ -24,13 +24,19 @@ duplicate detection, and source containment:
 
 `internal/profile` loads and validates execution profiles from an
 operating-system filesystem or an `fs.FS`. It supports a primary repository
-with fallback only when the primary reports that a profile is absent.
+with fallback only when the primary reports that a profile is absent. Strict
+YAML decoding recognizes the optional `backend` field, trims its value, and
+requires a model plus at least one non-blank backend or endpoint. Loading does
+not check registry membership because the available registry belongs to the
+assembled engine; the runner checks membership during preparation.
 
 `internal/profile/builtin` embeds the maintained built-in profile catalog and
-can place a caller-selected repository ahead of that catalog. Profile behavior
-is owned by the
+can place a caller-selected repository ahead of that catalog. Every embedded
+profile selects `openrouter` and inherits its endpoint and credential
+environment-variable name from the built-in backend registry rather than
+repeating those values. Profile behavior is owned by the
 [profile repository tests](../../internal/profile/repository_test.go), while
-catalog completeness, duplicate IDs, and overlay behavior are owned by the
+catalog completeness, backend-selection invariant, duplicate IDs, and overlay behavior are owned by the
 [built-in repository tests](../../internal/profile/builtin/repository_test.go).
 
 ## Ordinary Artifacts