fix(config): delete the model-routing chain — nothing has called it since April

Closes #116.

`config/models.yaml` declared a default chain and six per-skill chains. The
issue filed against it said the deployed service does not read the file. That
was true and understated: **nothing reads it at all**, and the loader written to
read it is dead too.

The whole chain goes:

- `config/models.yaml` — data with no consumer
- `internal/config/models.go` — `LoadModels` and `ModelFor`, whose only callers
  are in `models_test.go`
- `internal/config/config.go` — the `ModelsFile` field, assigned from
  `SUPERVISOR_MODELS_FILE` and never read
- `.env.example` — the variable that configures the path to the file nobody opens

Deleting the YAML alone would have left a loader pointing at a missing file:
one decoy replaced by another.

This subsystem had THREE PASSING TESTS. That is what kept it invisible. Green
assertions proving a function nobody calls works correctly are worse than no
tests, because coverage is exactly the signal someone would use to decide the
code is alive. The repo's own
`docs/superpowers/specs/2026-04-20-model-orchestration-design.md` said so in
April — "the model routing config exists but is dead weight" — and it survived
five more months anyway.

Two of the six models it named no longer exist (`iguana/qwen3-coder-next`,
retired in infra#416, and `koala/qwen3-coder-30b`, gone earlier). Nobody noticed
because the file being unread is the only reason it never failed.

Live routing is env, on the deployed `ingestion` service: `INGEST_LLM_MODEL`,
`BRAIN_LLM_PRIMARY_MODEL`, and four more. Not one name from the deleted file
appears there. Env is the real configuration surface; this file read as though
it were, which is why editing it to change routing would have changed nothing,
silently.

`go build ./...` clean, `task check` EXIT=0.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

.env.example

@@ -1,7 +1,6 @@
 # Supervisor MCP server
 SUPERVISOR_PORT=3200
 SUPERVISOR_CONFIG_DIR=./config/supervisor
-SUPERVISOR_MODELS_FILE=./config/models.yaml
 
 # LiteLLM gateway (iguana)
 LITELLM_BASE_URL=http://iguana:4000

config/models.yaml

@@ -1,26 +0,0 @@
-# Model selection — first entry per skill is used.
-# Override per-call by passing model in the MCP tool args.
-# Model names come from LiteLLM /v1/models (host/name format).
-
-default_chain:
-  - iguana/qwen3-coder-next
-
-skills:
-  tdd:
-    chain:
-      - koala/qwen3-coder-30b
-  review:
-    chain:
-      - iguana/devstral
-  debug:
-    chain:
-      - iguana/deepseek-r1-14b
-  spec:
-    chain:
-      - koala/phi4-14b
-  retrospective:
-    chain:
-      - iguana/qwen3-coder-next
-  trainer:
-    chain:
-      - iguana/qwen3-coder-next

internal/config/config.go

@@ -7,7 +7,6 @@ type Config struct {
 	LiteLLMBaseURL string // LITELLM_BASE_URL, default http://iguana:4000
 	LiteLLMAPIKey  string // LITELLM_API_KEY
 	ConfigDir      string // SUPERVISOR_CONFIG_DIR, default ./config/supervisor
-	ModelsFile     string // SUPERVISOR_MODELS_FILE, default <ConfigDir>/../models.yaml
 	IngestBaseURL  string // INGEST_BASE_URL, default http://localhost:3300
 	IngestSvcURL   string // INGEST_SVC_URL — base URL for brain_ingest (/ingest, /ingest-path)
 	KBRetrievalURL string // KB_RETRIEVAL_URL — base URL for brain_search
@@ -23,7 +22,6 @@ func Load() (Config, error) {
 		LiteLLMAPIKey:  os.Getenv("LITELLM_API_KEY"),
 		ConfigDir:      envOr("SUPERVISOR_CONFIG_DIR", "./config/supervisor"),
 	}
-	cfg.ModelsFile = envOr("SUPERVISOR_MODELS_FILE", cfg.ConfigDir+"/../models.yaml")
 	cfg.IngestBaseURL = envOr("INGEST_BASE_URL", "http://localhost:3300")
 	cfg.IngestSvcURL = envOr("INGEST_SVC_URL", "")
 	cfg.KBRetrievalURL = envOr("KB_RETRIEVAL_URL", "")

internal/config/models.go

@@ -1,49 +0,0 @@
-package config
-
-import (
-	"fmt"
-	"os"
-
-	"gopkg.in/yaml.v3"
-)
-
-type skillChain struct {
-	Chain []string `yaml:"chain"`
-}
-
-type modelsFile struct {
-	DefaultChain []string              `yaml:"default_chain"`
-	Skills       map[string]skillChain `yaml:"skills"`
-}
-
-type Models struct {
-	data modelsFile
-}
-
-func LoadModels(path string) (Models, error) {
-	raw, err := os.ReadFile(path)
-	if err != nil {
-		return Models{}, fmt.Errorf("load models: %w", err)
-	}
-	var f modelsFile
-	if err := yaml.Unmarshal(raw, &f); err != nil {
-		return Models{}, fmt.Errorf("parse models: %w", err)
-	}
-	return Models{data: f}, nil
-}
-
-// ModelFor returns the primary model to use for a skill.
-// If override is non-empty, it is returned directly.
-// Falls back to default_chain[0] when the skill has no explicit entry.
-func (m Models) ModelFor(skill, override string) string {
-	if override != "" {
-		return override
-	}
-	if sc, ok := m.data.Skills[skill]; ok && len(sc.Chain) > 0 {
-		return sc.Chain[0]
-	}
-	if len(m.data.DefaultChain) > 0 {
-		return m.data.DefaultChain[0]
-	}
-	return ""
-}

internal/config/models_test.go

@@ -1,53 +0,0 @@
-package config_test
-
-import (
-	"os"
-	"path/filepath"
-	"testing"
-
-	"git.d-ma.be/mathias/hyperguild/internal/config"
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-)
-
-const testYAML = `
-default_chain:
-  - ollama/qwen3-coder-30b-tuned
-  - claude-sonnet-4-6
-
-skills:
-  review:
-    chain:
-      - ollama/devstral-tuned
-      - ollama/gemma4
-      - claude-sonnet-4-6
-  spec:
-    chain:
-      - ollama/phi4
-      - claude-opus-4-6
-`
-
-func writeModels(t *testing.T, content string) string {
-	t.Helper()
-	f := filepath.Join(t.TempDir(), "models.yaml")
-	require.NoError(t, os.WriteFile(f, []byte(content), 0o644))
-	return f
-}
-
-func TestModelsModelForSkillWithEntry(t *testing.T) {
-	m, err := config.LoadModels(writeModels(t, testYAML))
-	require.NoError(t, err)
-	assert.Equal(t, "ollama/devstral-tuned", m.ModelFor("review", ""))
-}
-
-func TestModelsModelForDefaultFallback(t *testing.T) {
-	m, err := config.LoadModels(writeModels(t, testYAML))
-	require.NoError(t, err)
-	assert.Equal(t, "ollama/qwen3-coder-30b-tuned", m.ModelFor("trainer", ""))
-}
-
-func TestModelsModelForCallerOverride(t *testing.T) {
-	m, err := config.LoadModels(writeModels(t, testYAML))
-	require.NoError(t, err)
-	assert.Equal(t, "claude-opus-4-6", m.ModelFor("review", "claude-opus-4-6"))
-}