workspace-server/internal/handlers/handlers_extended_test.go

@@ -255,22 +255,20 @@ func TestExtended_SecretsListEmpty(t *testing.T) {
 // ---------- TestSecretsSet (Extended) ----------
 
 func TestExtended_SecretsSet(t *testing.T) {
-	// internal#691: the per-workspace strip gate now defaults to platform_managed
-	// on empty MOLECULE_LLM_BILLING_MODE (closed default). This test's intent is
-	// the happy path of persisting a vendor key, so put the org into byok which
-	// matches the pre-#691 implicit behavior of an unset env.
-	t.Setenv("MOLECULE_LLM_BILLING_MODE", "byok")
+	// internal#718 P2-B: the per-workspace strip gate keys off the DERIVED mode
+	// (org rung retired). This test's intent is the happy path of persisting a
+	// vendor key on a byok workspace; the realistic way a workspace is byok for
+	// a direct vendor-key write is an explicit operator override (the escape
+	// hatch the reject error itself points to: PUT /admin/.../llm-billing-mode).
+	// The override short-circuits the resolver to byok in a single read, so the
+	// bypass-list check is skipped and the write proceeds.
+	t.Setenv("MOLECULE_LLM_BILLING_MODE", "platform_managed") // org env ignored now
 	mock := setupTestDB(t)
 	handler := NewSecretsHandler(nil)
 
-	// internal#691: secrets.Set now consults ResolveLLMBillingMode before the
-	// strip gate. Mock returns no row → resolver falls through to the org
-	// default (byok, set via t.Setenv above) → bypass-list check is skipped
-	// and the write proceeds. This pattern is the test-side mirror of the
-	// real-prod fall-through behavior for a fresh workspace with no override.
 	mock.ExpectQuery(`SELECT llm_billing_mode FROM workspaces WHERE id = \$1`).
 		WithArgs("22222222-2222-2222-2222-222222222222").
-		WillReturnRows(sqlmock.NewRows([]string{"llm_billing_mode"}))
+		WillReturnRows(sqlmock.NewRows([]string{"llm_billing_mode"}).AddRow(LLMBillingModeBYOK))
 
 	// Expect INSERT (encrypted value is dynamic, use AnyArg)
 	mock.ExpectExec("INSERT INTO workspace_secrets").

workspace-server/internal/handlers/llm_billing_mode.go

@@ -43,10 +43,36 @@ import (
 	"database/sql"
 	"errors"
 	"fmt"
+	"log"
+	"sync"
 
+	"git.moleculesai.app/molecule-ai/molecule-core/workspace-server/internal/crypto"
 	"git.moleculesai.app/molecule-ai/molecule-core/workspace-server/internal/db"
+	"git.moleculesai.app/molecule-ai/molecule-core/workspace-server/internal/providers"
 )
 
+// providerManifest is the parsed provider registry, loaded once. The registry
+// is embedded (go:embed, no network) and immutable for the process lifetime, so
+// a single Load is safe to memoize. A load failure is cached too (registryErr):
+// it can only happen on a malformed embedded YAML, which is a build-time defect
+// the verify-providers-gen + sync gates already catch, so failing closed
+// (treat as "cannot derive" → platform default) is correct and we don't retry.
+var (
+	providerRegistryOnce     sync.Once
+	providerRegistryManifest *providers.Manifest
+	providerRegistryErr      error
+)
+
+func providerRegistry() (*providers.Manifest, error) {
+	providerRegistryOnce.Do(func() {
+		providerRegistryManifest, providerRegistryErr = providers.LoadManifest()
+		if providerRegistryErr != nil {
+			log.Printf("llm_billing_mode: FATAL — provider registry failed to load: %v (billing will default-closed to platform_managed)", providerRegistryErr)
+		}
+	})
+	return providerRegistryManifest, providerRegistryErr
+}
+
 // Constants mirror molecule-controlplane/internal/credits/llm_billing.go.
 // Kept as string literals (not imports) because workspace-server has no
 // build-time dependency on the CP module; the values are stable wire
@@ -67,6 +93,19 @@ const (
 	BillingModeSourceWorkspaceOverride BillingModeSource = "workspace_override"
 	BillingModeSourceOrgDefault        BillingModeSource = "org_default"
 	BillingModeSourceConstantFallback  BillingModeSource = "constant_fallback"
+	// BillingModeSourceDerivedProvider means the mode was DERIVED from the
+	// workspace's (runtime, model) via the provider registry — the SSOT
+	// (internal#718 P2-B). IsPlatform(derived) → platform_managed, else byok.
+	// This is the highest-precedence source after an explicit operator override
+	// and SUPERSEDES the prior stored-LLM_PROVIDER read (#1966).
+	BillingModeSourceDerivedProvider BillingModeSource = "derived_provider"
+	// BillingModeSourceDerivedDefault means the registry could not derive a
+	// provider for the (runtime, model) — no model, unknown runtime,
+	// unregistered/ambiguous model — so the mode defaulted closed to
+	// platform_managed (CTO-confirmed "unset → platform default"). Distinct from
+	// derived_provider so operators can see "we defaulted" vs "we derived
+	// platform".
+	BillingModeSourceDerivedDefault BillingModeSource = "derived_default"
 )
 
 // BillingModeResolution is the structured answer the admin GET route returns
@@ -74,11 +113,18 @@ const (
 // shape, so the resolver test asserts both the mode AND the source per case
 // (catches a bug where the right mode is returned via the wrong layer).
 type BillingModeResolution struct {
-	WorkspaceID       string             `json:"workspace_id"`
-	ResolvedMode      string             `json:"resolved_mode"`
-	WorkspaceOverride *string            `json:"workspace_override"` // nil = inherit
-	OrgDefault        string             `json:"org_default"`        // already default-closed by CP
-	Source            BillingModeSource  `json:"source"`
+	WorkspaceID       string            `json:"workspace_id"`
+	ResolvedMode      string            `json:"resolved_mode"`
+	WorkspaceOverride *string           `json:"workspace_override"` // nil = inherit
+	OrgDefault        string            `json:"org_default"`        // RETIRED as a billing source (internal#718 P2-B); always platform_managed, kept for wire-compat
+	Source            BillingModeSource `json:"source"`
+	// ProviderSelection surfaces the DERIVED provider name (internal#718 P2-B)
+	// when the mode came from the registry derivation — the literal provider the
+	// (runtime, model) resolved to (e.g. "platform", "kimi-coding", "openai"), or
+	// the raw model id when derivation failed. nil when an explicit operator
+	// override or the empty-id default decided. Lets the admin route answer "why
+	// is this workspace byok?" with the derived provider, not a stored value.
+	ProviderSelection *string `json:"provider_selection"`
 }
 
 // isKnownBillingMode is the enum-recognizer for the resolver's default-closed
@@ -95,24 +141,137 @@ func isKnownBillingMode(s string) bool {
 	}
 }
 
-// normalizeOrgDefault applies the same default-closed contract to the
-// org-level input as the workspace override gets. The org_default arrives
-// from tenant_config which already COALESCEs NULL → platform_managed at the
-// CP SQL layer, but we DO NOT trust that contract here — if CP regresses or
-// the tenant_config env wasn't populated (race on boot), we still default-
-// close. Same principle: never honor a garbled value.
-func normalizeOrgDefault(orgMode string) string {
-	if isKnownBillingMode(orgMode) {
-		return orgMode
+// readWorkspaceBillingOverride reads the OPTIONAL explicit operator override
+// (workspaces.llm_billing_mode). Returns:
+//
+//	(mode, true,  nil) — a recognized override is set → operator pinned the mode
+//	("",   false, nil) — NULL / garbled / row-missing → no explicit override
+//	("",   false, err) — DB error → caller defaults closed + propagates
+//
+// internal#718 P2-B retires the org rung; this column is the ONLY stored
+// billing signal that survives, and ONLY as an explicit override on top of the
+// derived provider (CTO 2026-05-27).
+func readWorkspaceBillingOverride(ctx context.Context, workspaceID string) (string, bool, error) {
+	var wsOverride sql.NullString
+	err := db.DB.QueryRowContext(ctx,
+		`SELECT llm_billing_mode FROM workspaces WHERE id = $1`,
+		workspaceID,
+	).Scan(&wsOverride)
+	switch {
+	case errors.Is(err, sql.ErrNoRows):
+		return "", false, nil
+	case err != nil:
+		return "", false, fmt.Errorf("resolve workspace llm_billing_mode override for %s: %w", workspaceID, err)
 	}
-	return LLMBillingModePlatformManaged
+	if wsOverride.Valid && isKnownBillingMode(wsOverride.String) {
+		return wsOverride.String, true, nil
+	}
+	return "", false, nil
 }
 
-// ResolveLLMBillingMode is the canonical resolver. Every code path that
-// previously gated on `os.Getenv("MOLECULE_LLM_BILLING_MODE") == "platform_managed"`
-// must call this instead and gate on the returned mode. The architectural
-// test (resolver_ast_test.go) asserts there is no remaining call site of
-// the old shape outside the resolver-input wiring.
+// ResolveLLMBillingModeDerived is the SSOT billing-mode resolver (internal#718
+// P2-B). It DERIVES the provider from (runtime, model) via the provider
+// registry and decides platform-vs-byok from IsPlatform(derived) — it does NOT
+// read a stored LLM_PROVIDER (superseding #1966's stored-read approach) and
+// does NOT read the org rung (retired, CTO 2026-05-27).
+//
+// Precedence (highest first):
+//
+//  1. EXPLICIT operator override (workspaces.llm_billing_mode, a recognized
+//     value). The only stored billing signal that survives — an escape hatch,
+//     not the primary signal.
+//  2. DERIVE: providers.DeriveProvider(runtime, model, availableAuthEnv).
+//     - resolves to the closed `platform` provider → platform_managed
+//     - resolves to any other (BYOK/third-party) provider → byok  ← THE FIX
+//  3. DEFAULT-CLOSED: derive fails (no model, unknown runtime, unregistered or
+//     ambiguous model) → platform_managed (CTO "unset → platform default"). A
+//     derive failure NEVER silently flips a workspace to byok (which would
+//     strip the platform creds it may legitimately need).
+//
+// availableAuthEnv is the set of auth-env-var NAMES present for the workspace
+// (never secret values) — the same disambiguation input DeriveProvider uses to
+// split anthropic-oauth from anthropic-api. May be nil.
+//
+// A returned error never prevents a decision: ResolvedMode is always a valid
+// enum value (default-closed). The error is informational (log + surface).
+func ResolveLLMBillingModeDerived(ctx context.Context, workspaceID, runtime, model string, availableAuthEnv []string) (BillingModeResolution, error) {
+	res := BillingModeResolution{
+		WorkspaceID: workspaceID,
+		// OrgDefault is retired as a billing source (internal#718 P2-B). Kept on
+		// the struct for wire-compat (admin route / CP mirror) but always the
+		// closed constant — never consulted in the decision.
+		OrgDefault: LLMBillingModePlatformManaged,
+	}
+
+	// Pre-provision context (no workspace row yet): no override to read, default
+	// closed. (DeriveProvider could still run from the passed runtime/model, but
+	// the no-id path historically does no DB work and the strip gate only runs
+	// post-create, so keep it a pure default to preserve that contract.)
+	if workspaceID == "" {
+		res.ResolvedMode = LLMBillingModePlatformManaged
+		res.Source = BillingModeSourceDerivedDefault
+		return res, nil
+	}
+
+	// Precedence 1: explicit operator override.
+	if mode, ok, err := readWorkspaceBillingOverride(ctx, workspaceID); err != nil {
+		// DB error — default closed AND propagate (never flip on a transient error).
+		res.ResolvedMode = LLMBillingModePlatformManaged
+		res.Source = BillingModeSourceConstantFallback
+		return res, err
+	} else if ok {
+		m := mode
+		res.WorkspaceOverride = &m
+		res.ResolvedMode = mode
+		res.Source = BillingModeSourceWorkspaceOverride
+		return res, nil
+	}
+
+	// Precedence 2: DERIVE the provider from (runtime, model).
+	manifest, mErr := providerRegistry()
+	if mErr != nil || manifest == nil {
+		// Registry unavailable (malformed embedded YAML — a build-time defect the
+		// gates catch). Default closed.
+		res.ResolvedMode = LLMBillingModePlatformManaged
+		res.Source = BillingModeSourceDerivedDefault
+		return res, mErr
+	}
+	provider, dErr := manifest.DeriveProvider(runtime, model, availableAuthEnv)
+	if dErr != nil {
+		// No model / unknown runtime / unregistered / ambiguous → default closed.
+		// NOT an error to the caller: an unregistered model is a legitimate
+		// "we can't say it's BYOK, so bill the platform default" outcome, and the
+		// only-registered gate at the create/config API is where an unregistered
+		// model is rejected loudly. Here we just fail closed for safety.
+		res.ResolvedMode = LLMBillingModePlatformManaged
+		res.Source = BillingModeSourceDerivedDefault
+		sel := model
+		if sel != "" {
+			res.ProviderSelection = &sel
+		}
+		return res, nil
+	}
+	derivedName := provider.Name
+	res.ProviderSelection = &derivedName
+	res.Source = BillingModeSourceDerivedProvider
+	if provider.IsPlatform() {
+		res.ResolvedMode = LLMBillingModePlatformManaged
+	} else {
+		// A specific (non-platform) vendor was derived → bring-your-own-key.
+		res.ResolvedMode = LLMBillingModeBYOK
+	}
+	return res, nil
+}
+
+// ResolveLLMBillingMode is the legacy-signature resolver retained for callers
+// that do not have (runtime, model) in hand (the admin GET/PUT route and the
+// secrets remote-pull path). It reads the workspace's stored runtime + model +
+// available auth env from the DB and delegates to the DERIVED resolver
+// (internal#718 P2-B) — the orgMode parameter is RETIRED (the org rung is no
+// longer a billing source) and is ignored; it stays in the signature only to
+// avoid churning the two callers in this PR. The architectural test asserts no
+// remaining code path gates on os.Getenv("MOLECULE_LLM_BILLING_MODE") for the
+// strip decision (that env is no longer read into the decision at all).
 //
 // Returning an error does NOT prevent the caller from making a decision —
 // the returned mode is always a valid enum value (default-closed to
@@ -120,75 +279,160 @@ func normalizeOrgDefault(orgMode string) string {
 // branch. The error is informational: log it, surface it to operators, but
 // the strip-gate decision is already safe.
 func ResolveLLMBillingMode(ctx context.Context, workspaceID, orgMode string) (BillingModeResolution, error) {
-	res := BillingModeResolution{
-		WorkspaceID: workspaceID,
-		OrgDefault:  normalizeOrgDefault(orgMode),
-	}
+	_ = orgMode // org rung retired (internal#718 P2-B); parameter ignored.
 
 	if workspaceID == "" {
-		// No workspace ID = pre-provision context (templating, validation).
-		// Resolve against the org default only, no DB read.
-		res.ResolvedMode = res.OrgDefault
-		res.Source = BillingModeSourceOrgDefault
-		if !isKnownBillingMode(orgMode) {
-			// Org default was garbled/NULL and we clamped to platform_managed.
-			// Mark the source as constant_fallback so the operator can see
-			// the clamp happened, not that the org "really" said platform_managed.
-			res.Source = BillingModeSourceConstantFallback
-		}
-		return res, nil
+		// Pre-provision context (templating, validation): default closed, no DB.
+		return ResolveLLMBillingModeDerived(ctx, "", "", "", nil)
 	}
 
-	var wsOverride sql.NullString
-	err := db.DB.QueryRowContext(ctx,
-		`SELECT llm_billing_mode FROM workspaces WHERE id = $1`,
+	// Precedence 1: explicit operator override. Read it FIRST so an overridden
+	// workspace short-circuits without the extra runtime/secrets reads (and so
+	// the query order is override → runtime → secrets, matching the derived
+	// resolver's own override-first precedence).
+	if mode, ok, err := readWorkspaceBillingOverride(ctx, workspaceID); err != nil {
+		return BillingModeResolution{
+			WorkspaceID:  workspaceID,
+			OrgDefault:   LLMBillingModePlatformManaged,
+			ResolvedMode: LLMBillingModePlatformManaged,
+			Source:       BillingModeSourceConstantFallback,
+		}, err
+	} else if ok {
+		m := mode
+		return BillingModeResolution{
+			WorkspaceID:       workspaceID,
+			OrgDefault:        LLMBillingModePlatformManaged,
+			ResolvedMode:      mode,
+			WorkspaceOverride: &m,
+			Source:            BillingModeSourceWorkspaceOverride,
+		}, nil
+	}
+
+	// Precedence 2: DERIVE. Read the stored (runtime, model, available-auth-env)
+	// so the derived resolver can DeriveProvider for callers that don't carry
+	// them (admin route, secrets remote-pull). A read miss/error degrades
+	// gracefully: pass the empty/partial inputs through — DeriveProvider then
+	// errors and the derived resolver defaults closed to platform_managed.
+	//
+	// ResolveLLMBillingModeDerived re-reads the override (NULL again here) before
+	// deriving; that one extra cheap read keeps the derived resolver a complete,
+	// independently-callable SSOT rather than splitting its precedence across two
+	// functions.
+	runtime, model, authEnv := readWorkspaceDeriveInputs(ctx, workspaceID)
+	return ResolveLLMBillingModeDerived(ctx, workspaceID, runtime, model, authEnv)
+}
+
+// readWorkspaceDeriveInputs loads the workspace's stored runtime + selected
+// model + the auth-env-var NAMES present in its secrets — the inputs
+// DeriveProvider needs. Best-effort: any read error returns whatever was
+// gathered (the derived resolver fails closed on incomplete inputs). The model
+// is the MODEL workspace_secret (the canvas-picked id, written by setModelSecret
+// / Create); runtime is the workspaces.runtime column (defaults claude-code).
+// availableAuthEnv is the subset of secret KEYS that are recognized provider
+// auth-env names (never values), so DeriveProvider's auth-env tie-break can fire
+// the same way it does on the provision path.
+func readWorkspaceDeriveInputs(ctx context.Context, workspaceID string) (runtime, model string, availableAuthEnv []string) {
+	var rt sql.NullString
+	if err := db.DB.QueryRowContext(ctx,
+		`SELECT runtime FROM workspaces WHERE id = $1`, workspaceID,
+	).Scan(&rt); err != nil {
+		if !errors.Is(err, sql.ErrNoRows) {
+			log.Printf("llm_billing_mode: read runtime for %s: %v (deriving with empty runtime)", workspaceID, err)
+		}
+	}
+	runtime = rt.String
+	if runtime == "" {
+		// Mirror the DB column default so an unset runtime still derives.
+		runtime = "claude-code"
+	}
+
+	// Gather model + auth-env-name keys from workspace_secrets in one pass.
+	authSet := authEnvNameSet()
+	rows, err := db.DB.QueryContext(ctx,
+		`SELECT key, encrypted_value, encryption_version FROM workspace_secrets WHERE workspace_id = $1`,
 		workspaceID,
-	).Scan(&wsOverride)
-
-	switch {
-	case errors.Is(err, sql.ErrNoRows):
-		// Workspace row missing — concurrent delete, or pre-create call. Don't
-		// silently flip; fall through to org default. Source stays org_default
-		// so operators can see the row-missing case is being handled as a
-		// fallback, not a workspace-explicit decision.
-		res.ResolvedMode = res.OrgDefault
-		res.Source = BillingModeSourceOrgDefault
-		if !isKnownBillingMode(orgMode) {
-			res.Source = BillingModeSourceConstantFallback
+	)
+	if err != nil {
+		log.Printf("llm_billing_mode: read secrets for %s: %v (deriving with no model/auth-env)", workspaceID, err)
+		return runtime, model, availableAuthEnv
+	}
+	defer rows.Close()
+	for rows.Next() {
+		var k string
+		var v []byte
+		var ver int
+		if rows.Scan(&k, &v, &ver) != nil {
+			continue
+		}
+		if k == "MODEL" {
+			if dec, derr := crypto.DecryptVersioned(v, ver); derr == nil {
+				model = string(dec)
+			}
+			continue
+		}
+		// Only the KEY matters for auth-env disambiguation (the value is the
+		// secret; we never decrypt it for this purpose). Record recognized
+		// provider auth-env names.
+		if _, ok := authSet[k]; ok {
+			availableAuthEnv = append(availableAuthEnv, k)
 		}
-		return res, nil
-	case err != nil:
-		// DB error — default-closed to platform_managed AND propagate the
-		// error so operators get a structured log line. The caller is
-		// expected to log and continue with the safe default.
-		res.ResolvedMode = LLMBillingModePlatformManaged
-		res.Source = BillingModeSourceConstantFallback
-		return res, fmt.Errorf("resolve workspace llm_billing_mode for %s: %w", workspaceID, err)
 	}
+	return runtime, model, availableAuthEnv
+}
 
-	if wsOverride.Valid && isKnownBillingMode(wsOverride.String) {
-		mode := wsOverride.String
-		res.WorkspaceOverride = &mode
-		res.ResolvedMode = mode
-		res.Source = BillingModeSourceWorkspaceOverride
-		return res, nil
-	}
+// authEnvNameSet is the union of every provider's auth_env names in the
+// registry — the recognized set readWorkspaceDeriveInputs filters secret keys
+// against. Loaded once from the registry so it stays in sync with the SSOT (no
+// hardcoded auth-env vocabulary). Registry-load failure yields an empty set
+// (derive then runs without the auth-env tie-break, which only matters for the
+// oauth-vs-api overlap; safe — it errors to default-closed rather than guessing).
+var (
+	authEnvNameSetOnce sync.Once
+	authEnvNameSetVal  map[string]struct{}
+)
 
-	// Override row present but the value is NULL or garbled. Fall through.
-	// If the value was non-NULL but garbled (CHECK constraint should prevent
-	// this, but defense in depth — a future migration could relax the check
-	// or another path could write the column directly), surface the raw
-	// override value so operators can spot the corrupt row.
-	if wsOverride.Valid {
-		raw := wsOverride.String
-		res.WorkspaceOverride = &raw
+func authEnvNameSet() map[string]struct{} {
+	authEnvNameSetOnce.Do(func() {
+		authEnvNameSetVal = map[string]struct{}{}
+		m, err := providerRegistry()
+		if err != nil || m == nil {
+			return
+		}
+		for _, p := range m.Providers {
+			for _, e := range p.AuthEnv {
+				authEnvNameSetVal[e] = struct{}{}
+			}
+		}
+	})
+	return authEnvNameSetVal
+}
+
+// availableAuthEnvNames returns the recognized provider auth-env-var NAMES
+// present (non-empty) in envVars — the DeriveProvider auth-env tie-break input.
+// Never returns secret VALUES, only the env-var names. Used by the provision
+// path (applyPlatformManagedLLMEnv), which already has the workspace env in
+// hand, so it derives without a secrets DB round-trip.
+func availableAuthEnvNames(envVars map[string]string) []string {
+	authSet := authEnvNameSet()
+	var out []string
+	for k, v := range envVars {
+		if v == "" {
+			continue
+		}
+		if _, ok := authSet[k]; ok {
+			out = append(out, k)
+		}
 	}
-	res.ResolvedMode = res.OrgDefault
-	res.Source = BillingModeSourceOrgDefault
-	if !isKnownBillingMode(orgMode) {
-		res.Source = BillingModeSourceConstantFallback
+	return out
+}
+
+// derefOrEmpty returns the pointed-to string or "" for a nil pointer. Used in
+// log lines that surface an optional *string field.
+func derefOrEmpty(s *string) string {
+	if s == nil {
+		return ""
 	}
-	return res, nil
+	return *s
 }
 
 // SetWorkspaceLLMBillingMode writes the override column. Pass mode=="" to

workspace-server/internal/handlers/llm_billing_mode_derived_test.go

@@ -0,0 +1,232 @@
+package handlers
+
+// llm_billing_mode_derived_test.go — tests for the DERIVED billing-mode
+// resolver (internal#718 P2-B). The platform-vs-byok decision now DERIVES the
+// provider from (runtime, model) via the provider registry and keys off
+// IsPlatform(derived) — it does NOT read a stored LLM_PROVIDER (supersedes
+// #1966's stored-read approach) and does NOT read the org rung (retired,
+// CTO 2026-05-27). `workspaces.llm_billing_mode` survives ONLY as an optional
+// explicit operator override (first precedence).
+//
+// This file pins the explicit BEHAVIOR DELTA the RFC's P2 calls out:
+//   - platform-derived (or unset → platform default) → platform_managed (UNCHANGED)
+//   - non-platform-derived                            → byok (THE FIX — the Reno leak class)
+//   - explicit override                               → wins over derive
+//   - derive error / unregistered                     → platform_managed (default-closed)
+
+import (
+	"context"
+	"errors"
+	"testing"
+
+	"github.com/DATA-DOG/go-sqlmock"
+)
+
+// expectOverrideQuery sets up the workspaces.llm_billing_mode override read
+// (first precedence). value=="" means NULL (no override).
+func expectOverrideQuery(m sqlmock.Sqlmock, wsID, value string) {
+	rows := sqlmock.NewRows([]string{"llm_billing_mode"})
+	if value == "" {
+		rows.AddRow(nil)
+	} else {
+		rows.AddRow(value)
+	}
+	m.ExpectQuery(`SELECT llm_billing_mode FROM workspaces WHERE id = \$1`).
+		WithArgs(wsID).
+		WillReturnRows(rows)
+}
+
+func TestResolveLLMBillingModeDerived_BehaviorDelta(t *testing.T) {
+	ctx := context.Background()
+	const wsID = "33333333-3333-3333-3333-333333333333"
+
+	type tc struct {
+		name       string
+		runtime    string
+		model      string
+		authEnv    []string
+		override   string // "" = NULL override (no explicit operator override)
+		wantMode   string
+		wantSource BillingModeSource
+		wantErr    bool
+	}
+
+	cases := []tc{
+		{
+			// PLATFORM-DERIVED → platform_managed (UNCHANGED). claude-code +
+			// a platform-namespaced model id derives to the closed `platform`
+			// provider → IsPlatform → platform_managed.
+			name:       "platform_derived_keeps_platform_managed_UNCHANGED",
+			runtime:    "claude-code",
+			model:      "anthropic/claude-opus-4-7",
+			override:   "",
+			wantMode:   LLMBillingModePlatformManaged,
+			wantSource: BillingModeSourceDerivedProvider,
+		},
+		{
+			// NON-PLATFORM-DERIVED → byok (THE FIX). claude-code + the
+			// kimi-coding-native model derives to the non-platform kimi-coding
+			// provider → IsPlatform=false → byok. This is the Reno billing-leak
+			// class: pre-P2 it resolved platform_managed and ran on platform creds.
+			name:       "non_platform_derived_resolves_byok_THE_FIX",
+			runtime:    "claude-code",
+			model:      "kimi-for-coding",
+			override:   "",
+			wantMode:   LLMBillingModeBYOK,
+			wantSource: BillingModeSourceDerivedProvider,
+		},
+		{
+			// NON-PLATFORM vendor on codex: gpt-5.5 derives to `openai` (BYOK).
+			name:       "non_platform_openai_codex_byok",
+			runtime:    "codex",
+			model:      "gpt-5.5",
+			override:   "",
+			wantMode:   LLMBillingModeBYOK,
+			wantSource: BillingModeSourceDerivedProvider,
+		},
+		{
+			// PLATFORM-DERIVED on codex: openai/gpt-5.4 is platform-namespaced.
+			name:       "platform_derived_codex_platform_managed",
+			runtime:    "codex",
+			model:      "openai/gpt-5.4",
+			override:   "",
+			wantMode:   LLMBillingModePlatformManaged,
+			wantSource: BillingModeSourceDerivedProvider,
+		},
+		{
+			// UNSET model → platform default (CTO-confirmed "unset → platform
+			// default"). No model means nothing to derive; default-closed.
+			name:       "unset_model_platform_default",
+			runtime:    "claude-code",
+			model:      "",
+			override:   "",
+			wantMode:   LLMBillingModePlatformManaged,
+			wantSource: BillingModeSourceDerivedDefault,
+		},
+		{
+			// UNREGISTERED model → derive errors → platform default (default-closed,
+			// NOT a silent byok flip that would strip a workspace's creds).
+			name:       "unregistered_model_derive_error_platform_default",
+			runtime:    "claude-code",
+			model:      "totally-made-up-model-xyz",
+			override:   "",
+			wantMode:   LLMBillingModePlatformManaged,
+			wantSource: BillingModeSourceDerivedDefault,
+		},
+		{
+			// UNKNOWN runtime → derive errors → platform default (default-closed).
+			name:       "unknown_runtime_platform_default",
+			runtime:    "no-such-runtime",
+			model:      "claude-opus-4-7",
+			override:   "",
+			wantMode:   LLMBillingModePlatformManaged,
+			wantSource: BillingModeSourceDerivedDefault,
+		},
+		{
+			// EXPLICIT OVERRIDE wins over derive: a non-platform-deriving model
+			// kept on platform_managed by an operator override (escape hatch).
+			name:       "explicit_override_platform_managed_wins_over_byok_derive",
+			runtime:    "claude-code",
+			model:      "kimi-for-coding", // would derive byok
+			override:   LLMBillingModePlatformManaged,
+			wantMode:   LLMBillingModePlatformManaged,
+			wantSource: BillingModeSourceWorkspaceOverride,
+		},
+		{
+			// EXPLICIT OVERRIDE byok wins over a platform-deriving model.
+			name:       "explicit_override_byok_wins_over_platform_derive",
+			runtime:    "claude-code",
+			model:      "anthropic/claude-opus-4-7", // would derive platform_managed
+			override:   LLMBillingModeBYOK,
+			wantMode:   LLMBillingModeBYOK,
+			wantSource: BillingModeSourceWorkspaceOverride,
+		},
+		{
+			// EXPLICIT OVERRIDE disabled wins (no-LLM workspace).
+			name:       "explicit_override_disabled_wins",
+			runtime:    "claude-code",
+			model:      "anthropic/claude-opus-4-7",
+			override:   LLMBillingModeDisabled,
+			wantMode:   LLMBillingModeDisabled,
+			wantSource: BillingModeSourceWorkspaceOverride,
+		},
+		{
+			// AUTH-ENV disambiguation: claude-code's anthropic-oauth (alias
+			// model "opus") vs anthropic-api both could match a bare alias; with
+			// CLAUDE_CODE_OAUTH_TOKEN present it derives anthropic-oauth → byok.
+			name:       "auth_env_disambiguates_oauth_byok",
+			runtime:    "claude-code",
+			model:      "opus",
+			authEnv:    []string{"CLAUDE_CODE_OAUTH_TOKEN"},
+			override:   "",
+			wantMode:   LLMBillingModeBYOK,
+			wantSource: BillingModeSourceDerivedProvider,
+		},
+	}
+
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			mock := setupTestDB(t)
+			expectOverrideQuery(mock, wsID, c.override)
+
+			res, err := ResolveLLMBillingModeDerived(ctx, wsID, c.runtime, c.model, c.authEnv)
+			if (err != nil) != c.wantErr {
+				t.Fatalf("err: got %v wantErr=%v", err, c.wantErr)
+			}
+			if res.ResolvedMode != c.wantMode {
+				t.Errorf("mode: got %q want %q", res.ResolvedMode, c.wantMode)
+			}
+			if res.Source != c.wantSource {
+				t.Errorf("source: got %q want %q", res.Source, c.wantSource)
+			}
+			if !isKnownBillingMode(res.ResolvedMode) {
+				t.Errorf("post-condition: resolved mode %q not a known enum", res.ResolvedMode)
+			}
+			if err := mock.ExpectationsWereMet(); err != nil {
+				t.Errorf("sqlmock expectations: %v", err)
+			}
+		})
+	}
+}
+
+// TestResolveLLMBillingModeDerived_OverrideDBError_DefaultClosed asserts a DB
+// error reading the override column defaults closed to platform_managed and
+// propagates the error — never silently flips a workspace off platform creds.
+func TestResolveLLMBillingModeDerived_OverrideDBError_DefaultClosed(t *testing.T) {
+	ctx := context.Background()
+	const wsID = "44444444-4444-4444-4444-444444444444"
+
+	mock := setupTestDB(t)
+	mock.ExpectQuery(`SELECT llm_billing_mode FROM workspaces WHERE id = \$1`).
+		WithArgs(wsID).
+		WillReturnError(errors.New("connection refused"))
+
+	res, err := ResolveLLMBillingModeDerived(ctx, wsID, "claude-code", "kimi-for-coding", nil)
+	if err == nil {
+		t.Fatalf("expected propagated DB error, got nil")
+	}
+	if res.ResolvedMode != LLMBillingModePlatformManaged {
+		t.Errorf("default-closed: DB error must resolve platform_managed, got %q", res.ResolvedMode)
+	}
+	if res.Source != BillingModeSourceConstantFallback {
+		t.Errorf("source: got %q want %q", res.Source, BillingModeSourceConstantFallback)
+	}
+}
+
+// TestResolveLLMBillingModeDerived_EmptyWorkspaceID_PlatformDefault asserts the
+// pre-provision context (no workspace id, no override read) defaults to
+// platform_managed without a DB query.
+func TestResolveLLMBillingModeDerived_EmptyWorkspaceID_PlatformDefault(t *testing.T) {
+	ctx := context.Background()
+	mock := setupTestDB(t) // no query expected
+	res, err := ResolveLLMBillingModeDerived(ctx, "", "claude-code", "kimi-for-coding", nil)
+	if err != nil {
+		t.Fatalf("unexpected err: %v", err)
+	}
+	if res.ResolvedMode != LLMBillingModePlatformManaged {
+		t.Errorf("empty workspace id must default platform_managed, got %q", res.ResolvedMode)
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("sqlmock expectations: %v", err)
+	}
+}

workspace-server/internal/handlers/llm_billing_mode_handler.go

@@ -36,10 +36,12 @@ import (
 
 // GetWorkspaceLLMBillingMode handles GET /admin/workspaces/:id/llm-billing-mode.
 //
-// Reads the workspace override + the org-level default (from the same
-// MOLECULE_LLM_BILLING_MODE env var the provisioner reads at strip-gate time —
-// keeps the two paths consistent so the GET result matches what the strip
-// gate would compute) and returns the structured resolution.
+// internal#718 P2-B: the resolution now DERIVES the provider from the
+// workspace's stored (runtime, model) via the registry (org rung retired). The
+// passed orgMode is ignored by the resolver; it is left here only to avoid
+// churning the call signature. The returned resolution matches what the
+// provision-time strip gate computes (same derived resolver), so operators see
+// the real platform-vs-byok decision + the derived provider in ProviderSelection.
 func GetWorkspaceLLMBillingMode(c *gin.Context) {
 	workspaceID := strings.TrimSpace(c.Param("id"))
 	if !uuidRegex.MatchString(workspaceID) {

workspace-server/internal/handlers/llm_billing_mode_handler_test.go

@@ -29,13 +29,42 @@ func init() {
 
 const testWSID = "44444444-4444-4444-4444-444444444444"
 
-func TestGetWorkspaceLLMBillingMode_HappyPath_InheritsOrgDefault(t *testing.T) {
-	t.Setenv("MOLECULE_LLM_BILLING_MODE", LLMBillingModeBYOK)
+// expectDeriveShimQueries sets up the three reads the legacy-signature
+// ResolveLLMBillingMode shim makes on a no-explicit-override path
+// (internal#718 P2-B): the override read (NULL here), the workspaces.runtime
+// read, and the workspace_secrets scan (for MODEL + auth-env names). model==""
+// means no MODEL secret row.
+func expectDeriveShimQueries(m sqlmock.Sqlmock, wsID, runtime, model string) {
+	nullOverride := func() {
+		m.ExpectQuery(`SELECT llm_billing_mode FROM workspaces WHERE id = \$1`).
+			WithArgs(wsID).
+			WillReturnRows(sqlmock.NewRows([]string{"llm_billing_mode"}).AddRow(nil))
+	}
+	// Order: override(NULL) shim check, runtime, secrets, override(NULL) again
+	// (the derived resolver re-checks the override as a complete SSOT).
+	nullOverride()
+	m.ExpectQuery(`SELECT runtime FROM workspaces WHERE id = \$1`).
+		WithArgs(wsID).
+		WillReturnRows(sqlmock.NewRows([]string{"runtime"}).AddRow(runtime))
+	secretRows := sqlmock.NewRows([]string{"key", "encrypted_value", "encryption_version"})
+	if model != "" {
+		// encryption_version 0 = plaintext passthrough (crypto.DecryptVersioned).
+		secretRows.AddRow("MODEL", []byte(model), 0)
+	}
+	m.ExpectQuery(`SELECT key, encrypted_value, encryption_version FROM workspace_secrets WHERE workspace_id = \$1`).
+		WithArgs(wsID).
+		WillReturnRows(secretRows)
+	nullOverride()
+}
+
+// internal#718 P2-B: org rung retired. A no-override workspace's mode is now
+// DERIVED from its stored (runtime, model). A claude-code workspace with a
+// non-platform-deriving model (kimi-for-coding) resolves byok via
+// derived_provider — NOT the old "inherit org default".
+func TestGetWorkspaceLLMBillingMode_HappyPath_DerivesByokFromModel(t *testing.T) {
+	t.Setenv("MOLECULE_LLM_BILLING_MODE", LLMBillingModeBYOK) // org env ignored now
 	mock := setupTestDB(t)
-	// Workspace has no override → resolver returns org_default = byok.
-	mock.ExpectQuery(`SELECT llm_billing_mode FROM workspaces WHERE id = \$1`).
-		WithArgs(testWSID).
-		WillReturnRows(sqlmock.NewRows([]string{"llm_billing_mode"}).AddRow(nil))
+	expectDeriveShimQueries(mock, testWSID, "claude-code", "kimi-for-coding")
 
 	w := httptest.NewRecorder()
 	c, _ := gin.CreateTestContext(w)
@@ -54,12 +83,15 @@ func TestGetWorkspaceLLMBillingMode_HappyPath_InheritsOrgDefault(t *testing.T) {
 	if res.ResolvedMode != LLMBillingModeBYOK {
 		t.Errorf("resolved mode: got %q want %q", res.ResolvedMode, LLMBillingModeBYOK)
 	}
-	if res.Source != BillingModeSourceOrgDefault {
-		t.Errorf("source: got %q want %q", res.Source, BillingModeSourceOrgDefault)
+	if res.Source != BillingModeSourceDerivedProvider {
+		t.Errorf("source: got %q want %q", res.Source, BillingModeSourceDerivedProvider)
 	}
 	if res.WorkspaceOverride != nil {
 		t.Errorf("expected nil override, got %v", *res.WorkspaceOverride)
 	}
+	if res.ProviderSelection == nil || *res.ProviderSelection != "kimi-coding" {
+		t.Errorf("expected derived provider kimi-coding, got %v", res.ProviderSelection)
+	}
 }
 
 func TestGetWorkspaceLLMBillingMode_BadUUID_400(t *testing.T) {
@@ -117,9 +149,9 @@ func TestPutWorkspaceLLMBillingMode_ExplicitNullClearsOverride(t *testing.T) {
 	mock.ExpectExec(`UPDATE workspaces SET llm_billing_mode = NULL WHERE id = \$1`).
 		WithArgs(testWSID).
 		WillReturnResult(sqlmock.NewResult(0, 1))
-	mock.ExpectQuery(`SELECT llm_billing_mode FROM workspaces WHERE id = \$1`).
-		WithArgs(testWSID).
-		WillReturnRows(sqlmock.NewRows([]string{"llm_billing_mode"}).AddRow(nil))
+	// After clear, the post-write re-resolution DERIVES (internal#718 P2-B):
+	// no override + no MODEL secret → derived_default → platform_managed.
+	expectDeriveShimQueries(mock, testWSID, "claude-code", "")
 
 	w := httptest.NewRecorder()
 	c, _ := gin.CreateTestContext(w)
@@ -142,8 +174,8 @@ func TestPutWorkspaceLLMBillingMode_ExplicitNullClearsOverride(t *testing.T) {
 	if res.ResolvedMode != LLMBillingModePlatformManaged {
 		t.Errorf("post-clear resolved: got %q want %q", res.ResolvedMode, LLMBillingModePlatformManaged)
 	}
-	if res.Source != BillingModeSourceOrgDefault {
-		t.Errorf("post-clear source: got %q want %q", res.Source, BillingModeSourceOrgDefault)
+	if res.Source != BillingModeSourceDerivedDefault {
+		t.Errorf("post-clear source: got %q want %q", res.Source, BillingModeSourceDerivedDefault)
 	}
 	if res.WorkspaceOverride != nil {
 		t.Errorf("post-clear override should be nil, got %v", *res.WorkspaceOverride)

workspace-server/internal/handlers/llm_billing_mode_test.go

@@ -1,10 +1,12 @@
 package handlers
 
-// llm_billing_mode_test.go — table-driven tests for the per-workspace
-// resolver (internal#691). The cases below enumerate every documented
-// branch in the default-closed contract; if one of them flips behavior
-// later the test names will tell the reviewer exactly which RFC clause
-// regressed.
+// llm_billing_mode_test.go — tests for the LEGACY-signature resolver
+// ResolveLLMBillingMode after internal#718 P2-B. The org rung is RETIRED: the
+// legacy shim now reads the explicit override first, then DERIVES the provider
+// from the workspace's stored (runtime, model) via the registry (no org
+// default). The dedicated derived-resolver cases live in
+// llm_billing_mode_derived_test.go; this file pins the legacy shim's DB-read
+// sequence + that it routes through the derived semantics.
 
 import (
 	"context"
@@ -14,35 +16,56 @@ import (
 	"github.com/DATA-DOG/go-sqlmock"
 )
 
-func TestResolveLLMBillingMode_TableDriven(t *testing.T) {
+// expectLegacyShimQueries sets up the DB reads the legacy ResolveLLMBillingMode
+// shim makes on a NO-explicit-override path (internal#718 P2-B), in order:
+//  1. override read (NULL) — the shim's own precedence-1 check,
+//  2. workspaces.runtime read,
+//  3. workspace_secrets scan (MODEL + auth-env names),
+//  4. override read AGAIN (NULL) — the derived resolver re-checks it so it is a
+//     complete, independently-callable SSOT.
+//
+// model=="" means no MODEL secret row.
+func expectLegacyShimQueries(m sqlmock.Sqlmock, wsID, runtime, model string) {
+	nullOverride := func() {
+		m.ExpectQuery(`SELECT llm_billing_mode FROM workspaces WHERE id = \$1`).
+			WithArgs(wsID).
+			WillReturnRows(sqlmock.NewRows([]string{"llm_billing_mode"}).AddRow(nil))
+	}
+	nullOverride()
+	m.ExpectQuery(`SELECT runtime FROM workspaces WHERE id = \$1`).
+		WithArgs(wsID).
+		WillReturnRows(sqlmock.NewRows([]string{"runtime"}).AddRow(runtime))
+	secretRows := sqlmock.NewRows([]string{"key", "encrypted_value", "encryption_version"})
+	if model != "" {
+		secretRows.AddRow("MODEL", []byte(model), 0) // version 0 = plaintext
+	}
+	m.ExpectQuery(`SELECT key, encrypted_value, encryption_version FROM workspace_secrets WHERE workspace_id = \$1`).
+		WithArgs(wsID).
+		WillReturnRows(secretRows)
+	nullOverride()
+}
+
+func TestResolveLLMBillingMode_LegacyShimDerives(t *testing.T) {
 	ctx := context.Background()
 	const wsID = "11111111-1111-1111-1111-111111111111"
 
 	type want struct {
-		mode   string
-		source BillingModeSource
-		// hasOverride asserts whether the resolver surfaced the override
-		// value in the result (nil pointer = clean inherit, non-nil = the
-		// row was present even if it ultimately fell through because it
-		// was garbled). Lets us distinguish "row missing, fell through"
-		// from "row present but garbled, fell through" — both resolve to
-		// the same mode but the resolver tells operators which case it was.
+		mode        string
+		source      BillingModeSource
 		hasOverride bool
 	}
 	type tc struct {
-		name        string
-		workspaceID string
-		orgMode     string
-		setupMock   func(m sqlmock.Sqlmock)
-		want        want
-		wantErr     bool
+		name      string
+		setupMock func(m sqlmock.Sqlmock)
+		want      want
+		wantErr   bool
 	}
 
 	cases := []tc{
 		{
-			name:        "workspace_override_byok_overrides_pm_org",
-			workspaceID: wsID,
-			orgMode:     LLMBillingModePlatformManaged,
+			// Explicit override still wins (first precedence; only stored signal
+			// that survives P2-B). No runtime/secrets read needed.
+			name: "explicit_override_byok_wins",
 			setupMock: func(m sqlmock.Sqlmock) {
 				m.ExpectQuery(`SELECT llm_billing_mode FROM workspaces WHERE id = \$1`).
 					WithArgs(wsID).
@@ -51,106 +74,60 @@ func TestResolveLLMBillingMode_TableDriven(t *testing.T) {
 			want: want{mode: LLMBillingModeBYOK, source: BillingModeSourceWorkspaceOverride, hasOverride: true},
 		},
 		{
-			name:        "workspace_override_disabled_overrides_pm_org",
-			workspaceID: wsID,
-			orgMode:     LLMBillingModePlatformManaged,
+			// No override + a non-platform-deriving model → byok via derive (THE
+			// FIX: pre-P2 this was platform_managed via the org rung).
+			name: "no_override_derives_byok_from_model",
 			setupMock: func(m sqlmock.Sqlmock) {
-				m.ExpectQuery(`SELECT llm_billing_mode FROM workspaces WHERE id = \$1`).
-					WithArgs(wsID).
-					WillReturnRows(sqlmock.NewRows([]string{"llm_billing_mode"}).AddRow(LLMBillingModeDisabled))
+				expectLegacyShimQueries(m, wsID, "claude-code", "kimi-for-coding")
 			},
-			want: want{mode: LLMBillingModeDisabled, source: BillingModeSourceWorkspaceOverride, hasOverride: true},
+			want: want{mode: LLMBillingModeBYOK, source: BillingModeSourceDerivedProvider, hasOverride: false},
 		},
 		{
-			name:        "workspace_override_null_inherits_byok_org",
-			workspaceID: wsID,
-			orgMode:     LLMBillingModeBYOK,
+			// No override + a platform-namespaced model → platform_managed (UNCHANGED).
+			name: "no_override_derives_platform_from_model",
 			setupMock: func(m sqlmock.Sqlmock) {
-				m.ExpectQuery(`SELECT llm_billing_mode FROM workspaces WHERE id = \$1`).
-					WithArgs(wsID).
-					WillReturnRows(sqlmock.NewRows([]string{"llm_billing_mode"}).AddRow(nil))
+				expectLegacyShimQueries(m, wsID, "claude-code", "anthropic/claude-opus-4-7")
 			},
-			want: want{mode: LLMBillingModeBYOK, source: BillingModeSourceOrgDefault, hasOverride: false},
+			want: want{mode: LLMBillingModePlatformManaged, source: BillingModeSourceDerivedProvider, hasOverride: false},
 		},
 		{
-			name:        "workspace_override_null_inherits_pm_org",
-			workspaceID: wsID,
-			orgMode:     LLMBillingModePlatformManaged,
+			// No override + no model → derived_default → platform_managed (unset → platform).
+			name: "no_override_no_model_platform_default",
 			setupMock: func(m sqlmock.Sqlmock) {
-				m.ExpectQuery(`SELECT llm_billing_mode FROM workspaces WHERE id = \$1`).
-					WithArgs(wsID).
-					WillReturnRows(sqlmock.NewRows([]string{"llm_billing_mode"}).AddRow(nil))
+				expectLegacyShimQueries(m, wsID, "claude-code", "")
 			},
-			want: want{mode: LLMBillingModePlatformManaged, source: BillingModeSourceOrgDefault, hasOverride: false},
+			want: want{mode: LLMBillingModePlatformManaged, source: BillingModeSourceDerivedDefault, hasOverride: false},
 		},
 		{
-			name:        "workspace_override_garbled_falls_through_to_pm_org_DEFAULT_CLOSED",
-			workspaceID: wsID,
-			orgMode:     LLMBillingModePlatformManaged,
+			// Garbled override is NOT honored — falls through to derive
+			// (default-closed). Here no model → platform default.
+			name: "garbled_override_falls_through_to_derive_default_closed",
 			setupMock: func(m sqlmock.Sqlmock) {
-				// CHECK constraint would normally prevent this but if a future
-				// migration loosens it (or a direct UPDATE bypasses it on a
-				// non-PG driver in a test stub), a garbled value MUST NOT
-				// be honored as if it were valid. This is the default-closed
-				// safety axis the RFC calls out.
+				// override read 1 (garbled → not honored), runtime, secrets,
+				// override read 2 (garbled again, derived resolver re-check).
+				m.ExpectQuery(`SELECT llm_billing_mode FROM workspaces WHERE id = \$1`).
+					WithArgs(wsID).
+					WillReturnRows(sqlmock.NewRows([]string{"llm_billing_mode"}).AddRow("byokk"))
+				m.ExpectQuery(`SELECT runtime FROM workspaces WHERE id = \$1`).
+					WithArgs(wsID).
+					WillReturnRows(sqlmock.NewRows([]string{"runtime"}).AddRow("claude-code"))
+				m.ExpectQuery(`SELECT key, encrypted_value, encryption_version FROM workspace_secrets WHERE workspace_id = \$1`).
+					WithArgs(wsID).
+					WillReturnRows(sqlmock.NewRows([]string{"key", "encrypted_value", "encryption_version"}))
 				m.ExpectQuery(`SELECT llm_billing_mode FROM workspaces WHERE id = \$1`).
 					WithArgs(wsID).
 					WillReturnRows(sqlmock.NewRows([]string{"llm_billing_mode"}).AddRow("byokk"))
 			},
-			want: want{mode: LLMBillingModePlatformManaged, source: BillingModeSourceOrgDefault, hasOverride: true},
+			want: want{mode: LLMBillingModePlatformManaged, source: BillingModeSourceDerivedDefault, hasOverride: false},
 		},
 		{
-			name:        "workspace_override_garbled_org_garbled_constant_fallback",
-			workspaceID: wsID,
-			orgMode:     "garbled-or-empty",
-			setupMock: func(m sqlmock.Sqlmock) {
-				m.ExpectQuery(`SELECT llm_billing_mode FROM workspaces WHERE id = \$1`).
-					WithArgs(wsID).
-					WillReturnRows(sqlmock.NewRows([]string{"llm_billing_mode"}).AddRow("nonsense"))
-			},
-			// Both layers garbled → constant fallback. Source is constant_fallback
-			// so operators can see the org-default-was-also-bad case explicitly.
-			want: want{mode: LLMBillingModePlatformManaged, source: BillingModeSourceConstantFallback, hasOverride: true},
-		},
-		{
-			name:        "workspace_row_missing_falls_through_to_org_byok",
-			workspaceID: wsID,
-			orgMode:     LLMBillingModeBYOK,
-			setupMock: func(m sqlmock.Sqlmock) {
-				m.ExpectQuery(`SELECT llm_billing_mode FROM workspaces WHERE id = \$1`).
-					WithArgs(wsID).
-					WillReturnRows(sqlmock.NewRows([]string{"llm_billing_mode"}))
-			},
-			want: want{mode: LLMBillingModeBYOK, source: BillingModeSourceOrgDefault, hasOverride: false},
-		},
-		{
-			name:        "workspace_id_empty_pre_provision_org_only",
-			workspaceID: "",
-			orgMode:     LLMBillingModeBYOK,
-			setupMock:   func(m sqlmock.Sqlmock) { /* no DB read expected — empty ws id short-circuits */ },
-			want:        want{mode: LLMBillingModeBYOK, source: BillingModeSourceOrgDefault, hasOverride: false},
-		},
-		{
-			name:        "workspace_id_empty_org_garbled_constant_fallback",
-			workspaceID: "",
-			orgMode:     "",
-			setupMock:   func(m sqlmock.Sqlmock) { /* no DB read */ },
-			want:        want{mode: LLMBillingModePlatformManaged, source: BillingModeSourceConstantFallback, hasOverride: false},
-		},
-		{
-			name:        "db_error_default_closed_to_pm_with_error",
-			workspaceID: wsID,
-			orgMode:     LLMBillingModeBYOK, // org says byok but DB errored — DO NOT honor org
+			// DB error on the override read → default-closed + propagated error.
+			name: "override_db_error_default_closed_with_error",
 			setupMock: func(m sqlmock.Sqlmock) {
 				m.ExpectQuery(`SELECT llm_billing_mode FROM workspaces WHERE id = \$1`).
 					WithArgs(wsID).
 					WillReturnError(errors.New("connection refused"))
 			},
-			// Critical: even though orgMode=byok, a DB error means we can't
-			// confirm the workspace doesn't have an override, so we default
-			// to the closed mode. This is the safer of the two failures —
-			// silently flipping to org-byok on a DB error would leak the
-			// OAuth-keeping behavior to workspaces whose row says NULL.
 			want:    want{mode: LLMBillingModePlatformManaged, source: BillingModeSourceConstantFallback, hasOverride: false},
 			wantErr: true,
 		},
@@ -161,7 +138,8 @@ func TestResolveLLMBillingMode_TableDriven(t *testing.T) {
 			mock := setupTestDB(t)
 			c.setupMock(mock)
 
-			res, err := ResolveLLMBillingMode(ctx, c.workspaceID, c.orgMode)
+			// orgMode arg is retired/ignored; pass a value to prove it has no effect.
+			res, err := ResolveLLMBillingMode(ctx, wsID, LLMBillingModeBYOK)
 			if (err != nil) != c.wantErr {
 				t.Fatalf("err: got %v wantErr=%v", err, c.wantErr)
 			}
@@ -172,8 +150,7 @@ func TestResolveLLMBillingMode_TableDriven(t *testing.T) {
 				t.Errorf("source: got %q want %q", res.Source, c.want.source)
 			}
 			if (res.WorkspaceOverride != nil) != c.want.hasOverride {
-				t.Errorf("hasOverride: got %v want %v (override=%v)",
-					res.WorkspaceOverride != nil, c.want.hasOverride, res.WorkspaceOverride)
+				t.Errorf("hasOverride: got %v want %v", res.WorkspaceOverride != nil, c.want.hasOverride)
 			}
 			if err := mock.ExpectationsWereMet(); err != nil {
 				t.Errorf("sqlmock expectations: %v", err)
@@ -182,21 +159,48 @@ func TestResolveLLMBillingMode_TableDriven(t *testing.T) {
 	}
 }
 
+// TestResolveLLMBillingMode_EmptyWorkspaceID_PlatformDefault: pre-provision
+// (no workspace id) defaults closed with no DB read (org rung retired, so the
+// old "org_only" behavior is gone — it's now the platform default).
+func TestResolveLLMBillingMode_EmptyWorkspaceID_PlatformDefault(t *testing.T) {
+	ctx := context.Background()
+	mock := setupTestDB(t) // no DB read expected
+	res, err := ResolveLLMBillingMode(ctx, "", LLMBillingModeBYOK)
+	if err != nil {
+		t.Fatalf("unexpected err: %v", err)
+	}
+	if res.ResolvedMode != LLMBillingModePlatformManaged {
+		t.Errorf("empty ws id must default platform_managed, got %q", res.ResolvedMode)
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("sqlmock expectations: %v", err)
+	}
+}
+
 // TestResolveLLMBillingMode_ResolvedModeIsAlwaysValid asserts the resolver's
 // post-condition: the returned mode is ALWAYS one of the three known enum
-// values, never an empty string and never a garbled passthrough. The strip
-// gate downstream relies on this so it can switch on res.ResolvedMode
-// without a separate is-valid check on every call site.
+// values. The strip gate downstream relies on this so it can switch on
+// res.ResolvedMode without a separate is-valid check on every call site.
 func TestResolveLLMBillingMode_ResolvedModeIsAlwaysValid(t *testing.T) {
 	ctx := context.Background()
 	const wsID = "22222222-2222-2222-2222-222222222222"
 
-	// Throw a pathological row at the resolver: garbled override + garbled
-	// org default. Resolved mode must still be a recognized enum.
+	// Garbled override + no derivable model: must still resolve a known enum
+	// (platform_managed, default-closed). Query order: override(garbled),
+	// runtime, secrets, override(garbled again — derived resolver re-check).
 	mock := setupTestDB(t)
 	mock.ExpectQuery(`SELECT llm_billing_mode FROM workspaces WHERE id = \$1`).
 		WithArgs(wsID).
 		WillReturnRows(sqlmock.NewRows([]string{"llm_billing_mode"}).AddRow("totally-bogus"))
+	mock.ExpectQuery(`SELECT runtime FROM workspaces WHERE id = \$1`).
+		WithArgs(wsID).
+		WillReturnRows(sqlmock.NewRows([]string{"runtime"}).AddRow("claude-code"))
+	mock.ExpectQuery(`SELECT key, encrypted_value, encryption_version FROM workspace_secrets WHERE workspace_id = \$1`).
+		WithArgs(wsID).
+		WillReturnRows(sqlmock.NewRows([]string{"key", "encrypted_value", "encryption_version"}))
+	mock.ExpectQuery(`SELECT llm_billing_mode FROM workspaces WHERE id = \$1`).
+		WithArgs(wsID).
+		WillReturnRows(sqlmock.NewRows([]string{"llm_billing_mode"}).AddRow("totally-bogus"))
 
 	res, err := ResolveLLMBillingMode(ctx, wsID, "also-bogus")
 	if err != nil {
@@ -206,7 +210,7 @@ func TestResolveLLMBillingMode_ResolvedModeIsAlwaysValid(t *testing.T) {
 		t.Errorf("post-condition violated: resolved mode %q is not a known enum value", res.ResolvedMode)
 	}
 	if res.ResolvedMode != LLMBillingModePlatformManaged {
-		t.Errorf("default-closed contract: garbled-x-garbled must resolve to platform_managed, got %q", res.ResolvedMode)
+		t.Errorf("default-closed contract: garbled-override + no-model must resolve platform_managed, got %q", res.ResolvedMode)
 	}
 }
 

workspace-server/internal/handlers/model_registry_validation.go

@@ -0,0 +1,57 @@
+package handlers
+
+// model_registry_validation.go — only-registered (runtime, model) validation
+// at the create/config API (internal#718 P2-B item 3, CTO 2026-05-27
+// "only registered providers/models selectable").
+//
+// The registry (internal/providers) is the SSOT for which models a runtime
+// natively exposes (ModelsForRuntime). This validator rejects a (runtime, model)
+// the registry does NOT recognize — but ONLY for a runtime the registry knows
+// about. For a runtime absent from the first-party registry (langgraph,
+// external, kimi, mock, or a future federated third-party runtime), it fails
+// OPEN: the registry can't speak to that runtime's model set, so the existing
+// knownRuntimes gate stays authoritative and this validator does not block.
+// This is the federation-ready contract — first-party runtimes are gated against
+// the registry; everything else passes through unchanged (no behavior change for
+// non-registry runtimes).
+
+import (
+	"fmt"
+	"strings"
+)
+
+// validateRegisteredModelForRuntime reports whether (runtime, model) is
+// selectable per the provider registry. Returns:
+//
+//	(true,  "")     — allowed: model is registered for this runtime, OR the
+//	                  runtime is not in the registry (fail-open), OR model=="".
+//	(false, reason) — rejected: the runtime IS registered but the model is not
+//	                  in its native ModelsForRuntime set.
+//
+// model=="" is allowed here: the MODEL_REQUIRED gate owns the empty-model case,
+// so this validator must not double-reject it.
+func validateRegisteredModelForRuntime(runtime, model string) (bool, string) {
+	model = strings.TrimSpace(model)
+	if model == "" {
+		return true, "" // MODEL_REQUIRED owns this.
+	}
+	m, err := providerRegistry()
+	if err != nil || m == nil {
+		// Registry unavailable (build-time defect the gates catch). Fail open —
+		// do not block create on a registry-load failure.
+		return true, ""
+	}
+	models, err := m.ModelsForRuntime(runtime)
+	if err != nil {
+		// Runtime not in the registry → fail open (federation / non-first-party).
+		return true, ""
+	}
+	for _, mid := range models {
+		if mid == model {
+			return true, ""
+		}
+	}
+	return false, fmt.Sprintf(
+		"model %q is not a registered model for runtime %q; pick one of the runtime's registered models (provider-registry SSOT, internal#718)",
+		model, runtime)
+}

workspace-server/internal/handlers/model_registry_validation_test.go

@@ -0,0 +1,82 @@
+package handlers
+
+// model_registry_validation_test.go — only-registered (runtime, model)
+// validation at the create/config API (internal#718 P2-B item 3). Reject a
+// (runtime, model) the registry does not recognize for a runtime it DOES know;
+// fail OPEN (allow) for a runtime the registry doesn't know yet (federation /
+// langgraph/etc. not in the first-party registry) so the existing knownRuntimes
+// gate stays authoritative there.
+
+import "testing"
+
+func TestValidateRegisteredModelForRuntime(t *testing.T) {
+	type tc struct {
+		name    string
+		runtime string
+		model   string
+		wantOK  bool // true = allowed (registered OR runtime-not-in-registry)
+	}
+	cases := []tc{
+		{
+			name:    "registered_platform_model_allowed",
+			runtime: "claude-code",
+			model:   "anthropic/claude-opus-4-7",
+			wantOK:  true,
+		},
+		{
+			name:    "registered_byok_model_allowed",
+			runtime: "claude-code",
+			model:   "kimi-for-coding",
+			wantOK:  true,
+		},
+		{
+			name:    "registered_codex_model_allowed",
+			runtime: "codex",
+			model:   "gpt-5.5",
+			wantOK:  true,
+		},
+		{
+			name:    "unregistered_model_for_known_runtime_rejected",
+			runtime: "claude-code",
+			model:   "totally-made-up-model-xyz",
+			wantOK:  false,
+		},
+		{
+			name:    "wrong_runtime_for_model_rejected",
+			runtime: "codex",
+			model:   "kimi-for-coding", // claude-code's, not codex's
+			wantOK:  false,
+		},
+		{
+			// langgraph is a real core runtime but NOT in the first-party
+			// registry → fail OPEN (the registry can't speak to it yet).
+			name:    "runtime_not_in_registry_allowed_failopen",
+			runtime: "langgraph",
+			model:   "anything-goes",
+			wantOK:  true,
+		},
+		{
+			// external/kimi/mock runtimes are not in the registry → fail open.
+			name:    "external_runtime_allowed_failopen",
+			runtime: "external",
+			model:   "whatever",
+			wantOK:  true,
+		},
+		{
+			// empty model → not this gate's job (MODEL_REQUIRED handles it);
+			// allow so we don't double-reject.
+			name:    "empty_model_allowed_other_gate_owns_it",
+			runtime: "claude-code",
+			model:   "",
+			wantOK:  true,
+		},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			ok, _ := validateRegisteredModelForRuntime(c.runtime, c.model)
+			if ok != c.wantOK {
+				t.Errorf("validateRegisteredModelForRuntime(%q,%q) ok=%v want %v", c.runtime, c.model, ok, c.wantOK)
+			}
+		})
+	}
+}

workspace-server/internal/handlers/workspace.go

@@ -428,6 +428,33 @@ func (h *WorkspaceHandler) Create(c *gin.Context) {
 		return
 	}
 
+	// internal#718 P2-B: ONLY-REGISTERED validation at the create boundary.
+	// For a runtime the provider registry knows (first-party:
+	// claude-code/codex/hermes/openclaw) this checks the (runtime, model) pair
+	// against the registry's native model set. Fails OPEN for runtimes the
+	// registry doesn't know (langgraph/external/kimi/mock/federated) so
+	// non-first-party flows are UNCHANGED. Skipped for external workspaces.
+	//
+	// P2 ENFORCEMENT MODE = WARN, not hard-reject (deliberate, scoped). The
+	// legacy colon-namespaced BYOK model vocabulary ("anthropic:claude-opus-4-7"
+	// etc.) is still live across the create/import/template corpus and is NOT
+	// yet reconciled into the registry's exact-id model sets — that convergence
+	// is P3 (canvas only-offers-registered) + P4 (template codegen). Hard-
+	// rejecting an unregistered (runtime, model) now would 422 those legitimate
+	// existing flows, a large behavior change outside P2's scope (P2's behavior
+	// delta is the billing/credential flip, below). So P2 surfaces the
+	// unregistered pair as a queryable warning + an X-Molecule-Model-Unregistered
+	// response header (operator/canvas signal) and lets create proceed; the gate
+	// flips to hard-reject (uncomment the 422 below) once P3/P4 land the
+	// vocabulary convergence. The registry model set is code-generated from the
+	// canonical providers.yaml (PR-A), so the check stays in sync with the SSOT.
+	if !isExternal {
+		if ok, why := validateRegisteredModelForRuntime(payload.Runtime, payload.Model); !ok {
+			log.Printf("Create: WARN unregistered model (runtime=%q model=%q): %s [internal#718 P2 warn-mode; hard-reject gated on P3/P4 vocabulary convergence]", payload.Runtime, payload.Model, why)
+			c.Header("X-Molecule-Model-Unregistered", "true")
+		}
+	}
+
 	ctx := c.Request.Context()
 
 	// Convert empty role to NULL

workspace-server/internal/handlers/workspace_provision.go

@@ -981,18 +981,32 @@ func applyRuntimeModelEnv(envVars map[string]string, runtime, model string) {
 type platformLLMEnvResult struct {
 	ResolvedMode     string
 	HasUsableLLMCred bool
+	// Source records which layer decided the mode (internal#718 P2-B):
+	// derived_provider (registry derivation), derived_default (derive failed →
+	// platform default), workspace_override (explicit operator pin), or
+	// constant_fallback (DB error). Surfaced for observability + asserted by the
+	// behavior-delta tests so a regression of "derived, not stored" flips red.
+	Source BillingModeSource
 }
 
 func applyPlatformManagedLLMEnv(ctx context.Context, envVars map[string]string, globalKeys map[string]struct{}, workspaceID, runtime, model string) platformLLMEnvResult {
-	orgMode := strings.ToLower(strings.TrimSpace(os.Getenv("MOLECULE_LLM_BILLING_MODE")))
-	res, resolveErr := ResolveLLMBillingMode(ctx, workspaceID, orgMode)
+	// internal#718 P2-B: the platform-vs-byok decision now DERIVES the provider
+	// from (runtime, model) via the registry and keys off IsPlatform(derived) —
+	// NOT a stored LLM_PROVIDER and NOT the org rung. This path already carries
+	// runtime + model + the workspace env, so it calls the DERIVED resolver
+	// directly (no DB round-trip for runtime/model). availableAuthEnv is the set
+	// of recognized provider auth-env-var NAMES present in envVars (the same
+	// disambiguation input the registry uses to split oauth-vs-api). The org-env
+	// MOLECULE_LLM_BILLING_MODE is NO LONGER read into the decision (retired).
+	availableAuthEnv := availableAuthEnvNames(envVars)
+	res, resolveErr := ResolveLLMBillingModeDerived(ctx, workspaceID, runtime, model, availableAuthEnv)
 	if resolveErr != nil {
 		// resolveErr != nil ⇒ resolver hit a DB error AND already defaulted
 		// res.ResolvedMode to platform_managed. Log + proceed; the safe default
 		// is already in place, no early return needed.
 		log.Printf("workspace_provision: resolve billing mode workspace=%s err=%v (defaulting to platform_managed)", workspaceID, resolveErr)
 	}
-	log.Printf("workspace_provision: billing mode workspace=%s resolved=%s source=%s org_default=%s", workspaceID, res.ResolvedMode, res.Source, res.OrgDefault)
+	log.Printf("workspace_provision: billing mode workspace=%s resolved=%s source=%s derived_provider=%s", workspaceID, res.ResolvedMode, res.Source, derefOrEmpty(res.ProviderSelection))
 	// internal#703: MOLECULE_LLM_BILLING_MODE in the container must reflect the
 	// RESOLVED per-workspace mode, not a hardcoded literal. Pre-fix this var was
 	// only emitted (hardcoded "platform_managed") on the strip path below, so a
@@ -1023,6 +1037,7 @@ func applyPlatformManagedLLMEnv(ctx context.Context, envVars map[string]string,
 		return platformLLMEnvResult{
 			ResolvedMode:     res.ResolvedMode,
 			HasUsableLLMCred: hasAnyPlatformManagedLLMKey(envVars),
+			Source:           res.Source,
 		}
 	}
 	baseURL := firstNonEmptyEnv("MOLECULE_LLM_BASE_URL", "OPENAI_BASE_URL")
@@ -1034,7 +1049,7 @@ func applyPlatformManagedLLMEnv(ctx context.Context, envVars map[string]string,
 		// here — but we report HasUsableLLMCred from whatever survived so the
 		// caller's fail-closed branch (non-platform only) is never reached on
 		// this path.
-		return platformLLMEnvResult{ResolvedMode: res.ResolvedMode, HasUsableLLMCred: true}
+		return platformLLMEnvResult{ResolvedMode: res.ResolvedMode, HasUsableLLMCred: true, Source: res.Source}
 	}
 	stripPlatformManagedLLMBypassEnv(envVars)
 
@@ -1066,7 +1081,7 @@ func applyPlatformManagedLLMEnv(ctx context.Context, envVars map[string]string,
 	// platform_managed: the CP proxy usage token (injected as ANTHROPIC_API_KEY
 	// / OPENAI_API_KEY above) IS the usable credential, so the workspace is
 	// never fail-closed on this path.
-	return platformLLMEnvResult{ResolvedMode: res.ResolvedMode, HasUsableLLMCred: true}
+	return platformLLMEnvResult{ResolvedMode: res.ResolvedMode, HasUsableLLMCred: true, Source: res.Source}
 }
 
 func stripPlatformManagedLLMBypassEnv(envVars map[string]string) {

workspace-server/internal/handlers/workspace_provision_shared_test.go

@@ -1141,20 +1141,38 @@ func TestApplyPlatformManagedLLMEnv_ClaudeCodeStripsVendorBYOK(t *testing.T) {
 	}
 }
 
+// internal#718 P2-B: byok is now DERIVED, not org-env-driven. A claude-code
+// workspace with NO explicit override + a non-platform-deriving model
+// (kimi-for-coding → kimi-coding) resolves byok and must NOT get the CP proxy
+// creds injected. (Pre-P2 this was driven by the org env MOLECULE_LLM_BILLING_MODE
+// with an empty workspace id; that mechanism is retired.)
 func TestApplyPlatformManagedLLMEnv_NoopsOutsidePlatformManaged(t *testing.T) {
-	t.Setenv("MOLECULE_LLM_BILLING_MODE", "byok")
+	const wsID = "aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee"
+	mock := setupTestDB(t)
+	// No explicit override → derive from (claude-code, kimi-for-coding) → byok.
+	mock.ExpectQuery(`SELECT llm_billing_mode FROM workspaces WHERE id = \$1`).
+		WithArgs(wsID).
+		WillReturnRows(sqlmock.NewRows([]string{"llm_billing_mode"}).AddRow(nil))
+
+	t.Setenv("MOLECULE_LLM_BILLING_MODE", "platform_managed") // org env ignored now
 	t.Setenv("MOLECULE_LLM_BASE_URL", "https://api.example.test/api/v1/internal/llm/openai/v1")
 	t.Setenv("MOLECULE_LLM_USAGE_TOKEN", "tenant-admin-token")
 
 	envVars := map[string]string{}
-	applyPlatformManagedLLMEnv(context.Background(), envVars, nil, "", "claude-code", "")
+	res := applyPlatformManagedLLMEnv(context.Background(), envVars, nil, wsID, "claude-code", "kimi-for-coding")
 
+	if res.ResolvedMode != LLMBillingModeBYOK {
+		t.Fatalf("resolved mode = %q, want byok (derived from non-platform model)", res.ResolvedMode)
+	}
 	if _, ok := envVars["OPENAI_API_KEY"]; ok {
 		t.Fatalf("OPENAI_API_KEY should not be set outside platform-managed mode")
 	}
 	if _, ok := envVars["MOLECULE_LLM_USAGE_TOKEN"]; ok {
 		t.Fatalf("MOLECULE_LLM_USAGE_TOKEN should not be set outside platform-managed mode")
 	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet sqlmock expectations: %v", err)
+	}
 }
 
 // TestApplyPlatformManagedLLMEnv_ClaudeCodeByokKeepsOwnProviderEnv is the
@@ -1274,6 +1292,136 @@ func TestApplyPlatformManagedLLMEnv_ByokStripsGlobalOriginOAuthToken(t *testing.
 	}
 }
 
+// =========================================================================
+// internal#718 P2-B BEHAVIOR DELTA — billing/credential decision DERIVES the
+// provider (no stored LLM_PROVIDER, no override). These three tests are the
+// explicit delta the RFC calls out, exercised through the real provision path
+// (applyPlatformManagedLLMEnv) with the registry derivation driving the mode:
+//   - platform-derived → platform_managed → platform creds (UNCHANGED)
+//   - non-platform-derived → byok → #1963 strip + fail-closed (THE FIX)
+//   - unset model → platform default (CTO-confirmed)
+// All use NO explicit override (override read returns NULL) so the DERIVATION
+// is what decides — this is what supersedes #1966's stored-LLM_PROVIDER read.
+// =========================================================================
+
+// PLATFORM-DERIVED → UNCHANGED. A claude-code workspace with a platform-
+// namespaced model (anthropic/claude-opus-4-7) derives to the closed `platform`
+// provider → platform_managed → CP proxy creds injected, exactly as before.
+func TestApplyPlatformManagedLLMEnv_DERIVED_PlatformModelKeepsPlatformCreds(t *testing.T) {
+	const wsID = "11111111-2222-3333-4444-555555555555"
+	mock := setupTestDB(t)
+	mock.ExpectQuery(`SELECT llm_billing_mode FROM workspaces WHERE id = \$1`).
+		WithArgs(wsID).
+		WillReturnRows(sqlmock.NewRows([]string{"llm_billing_mode"}).AddRow(nil)) // NO override → derive
+
+	t.Setenv("MOLECULE_LLM_BILLING_MODE", LLMBillingModeBYOK) // org env IGNORED now
+	t.Setenv("MOLECULE_LLM_BASE_URL", "https://api.example.test/api/v1/internal/llm/openai/v1")
+	t.Setenv("MOLECULE_LLM_ANTHROPIC_BASE_URL", "https://api.example.test/api/v1/internal/llm/anthropic")
+	t.Setenv("MOLECULE_LLM_USAGE_TOKEN", "tenant-admin-token")
+
+	envVars := map[string]string{}
+	res := applyPlatformManagedLLMEnv(context.Background(), envVars, nil, wsID, "claude-code", "anthropic/claude-opus-4-7")
+
+	if res.ResolvedMode != LLMBillingModePlatformManaged {
+		t.Fatalf("platform-derived model must resolve platform_managed, got %q (source=%s)", res.ResolvedMode, res.Source)
+	}
+	if res.Source != BillingModeSourceDerivedProvider {
+		t.Errorf("source: got %q want derived_provider", res.Source)
+	}
+	// Platform path injects the CP proxy creds (UNCHANGED behavior).
+	if got := envVars["ANTHROPIC_API_KEY"]; got != "tenant-admin-token" {
+		t.Errorf("platform path must inject the CP proxy token as ANTHROPIC_API_KEY, got %q", got)
+	}
+	if !res.HasUsableLLMCred {
+		t.Errorf("platform path always has a usable cred (the proxy token)")
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet sqlmock expectations: %v", err)
+	}
+}
+
+// NON-PLATFORM-DERIVED → byok + STRIP + FAIL-CLOSED signal (THE FIX, the Reno
+// billing-leak class). A claude-code workspace with a non-platform model
+// (kimi-for-coding → kimi-coding) and NO override + NO own cred, inheriting only
+// the platform's scope:global OAuth token, now DERIVES byok → #1963 strips the
+// global token → HasUsableLLMCred=false → caller fails closed. Pre-P2 this same
+// workspace resolved platform_managed (via the never-written org rung) and ran
+// on the platform's credits. This is the discriminating delta test.
+func TestApplyPlatformManagedLLMEnv_DERIVED_NonPlatformModelStripsAndFailsClosed(t *testing.T) {
+	const wsID = "99999999-8888-7777-6666-555555555555"
+	mock := setupTestDB(t)
+	mock.ExpectQuery(`SELECT llm_billing_mode FROM workspaces WHERE id = \$1`).
+		WithArgs(wsID).
+		WillReturnRows(sqlmock.NewRows([]string{"llm_billing_mode"}).AddRow(nil)) // NO override → derive
+
+	t.Setenv("MOLECULE_LLM_BILLING_MODE", LLMBillingModePlatformManaged) // org env IGNORED now
+	t.Setenv("MOLECULE_LLM_BASE_URL", "https://api.example.test/api/v1/internal/llm/openai/v1")
+	t.Setenv("MOLECULE_LLM_USAGE_TOKEN", "tenant-admin-token")
+
+	// Only LLM cred is the platform's scope:global OAuth token (globalKeys).
+	envVars := map[string]string{
+		"CLAUDE_CODE_OAUTH_TOKEN": "PLATFORM-GLOBAL-OAUTH-TOKEN",
+	}
+	globalKeys := map[string]struct{}{"CLAUDE_CODE_OAUTH_TOKEN": {}}
+
+	res := applyPlatformManagedLLMEnv(context.Background(), envVars, globalKeys, wsID, "claude-code", "kimi-for-coding")
+
+	// 1. DERIVED byok (NOT the old platform_managed default).
+	if res.ResolvedMode != LLMBillingModeBYOK {
+		t.Fatalf("non-platform-derived model must resolve byok, got %q (source=%s) — THE FIX regressed", res.ResolvedMode, res.Source)
+	}
+	if res.Source != BillingModeSourceDerivedProvider {
+		t.Errorf("source: got %q want derived_provider", res.Source)
+	}
+	// 2. #1963 strip: the platform global OAuth token is removed (leak closed).
+	if got, ok := envVars["CLAUDE_CODE_OAUTH_TOKEN"]; ok {
+		t.Fatalf("CLAUDE_CODE_OAUTH_TOKEN = %q present — must be stripped for a derived-byok workspace (Reno leak)", got)
+	}
+	// 3. No CP proxy creds forced.
+	if got, ok := envVars["ANTHROPIC_API_KEY"]; ok {
+		t.Fatalf("ANTHROPIC_API_KEY must NOT be injected for byok, got %q", got)
+	}
+	// 4. No usable cred → caller (prepareProvisionContext) fails closed.
+	if res.HasUsableLLMCred {
+		t.Fatalf("HasUsableLLMCred = true, want false (only the stripped platform global token was present)")
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet sqlmock expectations: %v", err)
+	}
+}
+
+// UNSET model → PLATFORM DEFAULT (CTO-confirmed "unset → platform default").
+// No model means nothing to derive; the workspace defaults closed to
+// platform_managed and keeps the platform creds (UNCHANGED for the no-model case).
+func TestApplyPlatformManagedLLMEnv_DERIVED_UnsetModelPlatformDefault(t *testing.T) {
+	const wsID = "00000000-1111-2222-3333-444444444444"
+	mock := setupTestDB(t)
+	mock.ExpectQuery(`SELECT llm_billing_mode FROM workspaces WHERE id = \$1`).
+		WithArgs(wsID).
+		WillReturnRows(sqlmock.NewRows([]string{"llm_billing_mode"}).AddRow(nil)) // NO override
+
+	t.Setenv("MOLECULE_LLM_BILLING_MODE", LLMBillingModeBYOK) // org env IGNORED now
+	t.Setenv("MOLECULE_LLM_BASE_URL", "https://api.example.test/api/v1/internal/llm/openai/v1")
+	t.Setenv("MOLECULE_LLM_ANTHROPIC_BASE_URL", "https://api.example.test/api/v1/internal/llm/anthropic")
+	t.Setenv("MOLECULE_LLM_USAGE_TOKEN", "tenant-admin-token")
+
+	envVars := map[string]string{}
+	res := applyPlatformManagedLLMEnv(context.Background(), envVars, nil, wsID, "claude-code", "")
+
+	if res.ResolvedMode != LLMBillingModePlatformManaged {
+		t.Fatalf("unset model must default platform_managed, got %q (source=%s)", res.ResolvedMode, res.Source)
+	}
+	if res.Source != BillingModeSourceDerivedDefault {
+		t.Errorf("source: got %q want derived_default", res.Source)
+	}
+	if got := envVars["ANTHROPIC_API_KEY"]; got != "tenant-admin-token" {
+		t.Errorf("unset-model platform default must inject the CP proxy token, got %q", got)
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unmet sqlmock expectations: %v", err)
+	}
+}
+
 // TestApplyPlatformManagedLLMEnv_ByokKeepsWorkspaceOwnOAuthEvenWithGlobal is
 // the discriminating companion to the strip test: a byok workspace that DID
 // set its own CLAUDE_CODE_OAUTH_TOKEN via the canvas Secrets tab (a

workspace-server/internal/handlers/workspace_test.go

@@ -501,10 +501,12 @@ func TestWorkspaceCreate_WithSecrets_Persists(t *testing.T) {
 // while persisting a secret causes the entire transaction to roll back and
 // the handler to return 500.  The workspace row must NOT be committed.
 func TestWorkspaceCreate_SecretPersistFails_RollsBack(t *testing.T) {
-	// internal#691: see TestExtended_SecretsSet — same default-closed reasoning.
-	// This test is asserting the rollback path on DB failure, not the strip gate;
-	// keep the org in byok so the OPENAI_API_KEY write reaches the INSERT.
-	t.Setenv("MOLECULE_LLM_BILLING_MODE", "byok")
+	// internal#718 P2-B: this test asserts the rollback path on DB failure, not
+	// the strip gate. The create-time secret gate keys off the DERIVED mode now
+	// (org rung retired). An explicit byok override makes the workspace byok in a
+	// single resolver read (precedence-1 short-circuit), so the OPENAI_API_KEY
+	// write is allowed and reaches the INSERT-and-fail path this test exercises.
+	t.Setenv("MOLECULE_LLM_BILLING_MODE", "platform_managed") // org env ignored now
 	mock := setupTestDB(t)
 	setupTestRedis(t)
 	broadcaster := newTestBroadcaster()
@@ -513,14 +515,11 @@ func TestWorkspaceCreate_SecretPersistFails_RollsBack(t *testing.T) {
 	mock.ExpectBegin()
 	mock.ExpectExec("INSERT INTO workspaces").
 		WillReturnResult(sqlmock.NewResult(0, 1))
-	// internal#691: Create() now resolves billing mode per-workspace before
-	// the secret-strip gate. The workspace row was just inserted in the same
-	// transaction so it isn't readable from a separate query yet; the
-	// resolver expects the SELECT and the mock returns no row → falls back
-	// to the org default (byok, set above) so the OPENAI_API_KEY write
-	// reaches the INSERT-and-fail path this test exercises.
+	// Create() resolves billing mode per-workspace before the secret-strip gate.
+	// An explicit byok override short-circuits the resolver (precedence 1) so the
+	// OPENAI_API_KEY write is allowed and reaches the INSERT-and-fail path.
 	mock.ExpectQuery(`SELECT llm_billing_mode FROM workspaces WHERE id = \$1`).
-		WillReturnRows(sqlmock.NewRows([]string{"llm_billing_mode"}))
+		WillReturnRows(sqlmock.NewRows([]string{"llm_billing_mode"}).AddRow(LLMBillingModeBYOK))
 	mock.ExpectExec("INSERT INTO workspace_secrets").
 		WillReturnError(sql.ErrConnDone) // DB failure while writing secret
 	mock.ExpectRollback() // workspace insert must be rolled back
@@ -2048,6 +2047,111 @@ func TestWorkspaceCreate_188_NoTemplateNoRuntime_NowMODEL_REQUIRED(t *testing.T)
 	}
 }
 
+// internal#718 P2-B: only-registered validation in P2 WARN-mode. A known
+// (registry) runtime with a model NOT in its registered set is allowed to
+// proceed (201) but flagged with the X-Molecule-Model-Unregistered response
+// header + a queryable warning log. (Hard-reject is gated on P3/P4 vocabulary
+// convergence — see the create handler comment; flipping to 422 there is a
+// one-line change once the legacy colon-form model vocabulary is reconciled.)
+func TestWorkspaceCreate_718_UnregisteredModelWarnsButProceeds(t *testing.T) {
+	mock := setupTestDB(t)
+	setupTestRedis(t)
+	broadcaster := newTestBroadcaster()
+	handler := NewWorkspaceHandler(broadcaster, nil, "http://localhost:8080", t.TempDir())
+
+	mock.ExpectBegin()
+	mock.ExpectExec("INSERT INTO workspaces").
+		WillReturnResult(sqlmock.NewResult(0, 1))
+	mock.ExpectCommit()
+	mock.ExpectExec("INSERT INTO workspace_secrets").
+		WillReturnResult(sqlmock.NewResult(0, 1))
+	mock.ExpectExec("INSERT INTO canvas_layouts").
+		WillReturnResult(sqlmock.NewResult(0, 1))
+	mock.ExpectExec("INSERT INTO structure_events").
+		WillReturnResult(sqlmock.NewResult(0, 1))
+
+	w := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(w)
+	body := `{"name":"Bad Model","runtime":"claude-code","model":"totally-made-up-xyz"}`
+	c.Request = httptest.NewRequest("POST", "/workspaces", bytes.NewBufferString(body))
+	c.Request.Header.Set("Content-Type", "application/json")
+	handler.Create(c)
+
+	if w.Code != http.StatusCreated {
+		t.Fatalf("unregistered-model create (warn-mode): expected 201, got %d: %s", w.Code, w.Body.String())
+	}
+	if w.Header().Get("X-Molecule-Model-Unregistered") != "true" {
+		t.Errorf("expected X-Molecule-Model-Unregistered=true header on unregistered model, got %q", w.Header().Get("X-Molecule-Model-Unregistered"))
+	}
+}
+
+// A REGISTERED model on a registry runtime sets NO unregistered header.
+func TestWorkspaceCreate_718_RegisteredModelNoWarnHeader(t *testing.T) {
+	mock := setupTestDB(t)
+	setupTestRedis(t)
+	broadcaster := newTestBroadcaster()
+	handler := NewWorkspaceHandler(broadcaster, nil, "http://localhost:8080", t.TempDir())
+
+	mock.ExpectBegin()
+	mock.ExpectExec("INSERT INTO workspaces").
+		WillReturnResult(sqlmock.NewResult(0, 1))
+	mock.ExpectCommit()
+	mock.ExpectExec("INSERT INTO workspace_secrets").
+		WillReturnResult(sqlmock.NewResult(0, 1))
+	mock.ExpectExec("INSERT INTO canvas_layouts").
+		WillReturnResult(sqlmock.NewResult(0, 1))
+	mock.ExpectExec("INSERT INTO structure_events").
+		WillReturnResult(sqlmock.NewResult(0, 1))
+
+	w := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(w)
+	// claude-opus-4-7 IS a registered claude-code model (anthropic-api).
+	body := `{"name":"Good Model","runtime":"claude-code","model":"claude-opus-4-7"}`
+	c.Request = httptest.NewRequest("POST", "/workspaces", bytes.NewBufferString(body))
+	c.Request.Header.Set("Content-Type", "application/json")
+	handler.Create(c)
+
+	if w.Code != http.StatusCreated {
+		t.Fatalf("registered-model create: expected 201, got %d: %s", w.Code, w.Body.String())
+	}
+	if w.Header().Get("X-Molecule-Model-Unregistered") != "" {
+		t.Errorf("registered model must NOT set the unregistered header, got %q", w.Header().Get("X-Molecule-Model-Unregistered"))
+	}
+}
+
+// internal#718 P2-B: a runtime NOT in the registry (mock — a known core runtime
+// absent from the first-party provider registry) fails OPEN — the
+// only-registered gate does not block it (federation / non-first-party path
+// unchanged). It proceeds past the gate to the normal create flow.
+func TestWorkspaceCreate_718_NonRegistryRuntimeFailsOpen(t *testing.T) {
+	mock := setupTestDB(t)
+	setupTestRedis(t)
+	broadcaster := newTestBroadcaster()
+	handler := NewWorkspaceHandler(broadcaster, nil, "http://localhost:8080", t.TempDir())
+
+	mock.ExpectBegin()
+	mock.ExpectExec("INSERT INTO workspaces").
+		WillReturnResult(sqlmock.NewResult(0, 1))
+	mock.ExpectCommit()
+	mock.ExpectExec("INSERT INTO canvas_layouts").
+		WillReturnResult(sqlmock.NewResult(0, 1))
+	mock.ExpectExec("INSERT INTO structure_events").
+		WillReturnResult(sqlmock.NewResult(0, 1))
+
+	w := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(w)
+	// "mock" is a known core runtime but NOT in the first-party registry;
+	// any model passes the only-registered gate (fail-open).
+	body := `{"name":"Mock Agent","runtime":"mock","model":"canned-replies"}`
+	c.Request = httptest.NewRequest("POST", "/workspaces", bytes.NewBufferString(body))
+	c.Request.Header.Set("Content-Type", "application/json")
+	handler.Create(c)
+
+	if w.Code != http.StatusCreated {
+		t.Fatalf("non-registry runtime should fail open (201), got %d: %s", w.Code, w.Body.String())
+	}
+}
+
 // Explicit runtime, no template → honored, 201 (no template resolution
 // needed; runtimeExplicitlyRequested true but already resolved).
 func TestWorkspaceCreate_188_ExplicitRuntimeNoTemplate_OK(t *testing.T) {