2 files changed, 146 insertions, 0 deletions
diff --git a/internal/role/role.go b/internal/role/role.go
new file mode 100644
index 0000000..f65edba
--- /dev/null
+++ b/internal/role/role.go
@@ -0,0 +1,73 @@
+// Package role defines the per-role configuration shape (system prompt, tool
+// allowlist, sandbox kind, budget, and — the part actually driven this phase —
+// a multi-tier provider/model escalation ladder) used by the token-husbanding
+// harness. A RoleConfig is stored as a versioned row in storage's
+// role_configs table (see internal/storage/roleconfig.go); internal/executor
+// resolves tier 0 of a role's EscalationLadder for the initial dispatch of a
+// role-typed task, and internal/scheduler walks the ladder on failure
+// (retry-then-escalate).
+//
+// Not everything on RoleConfig is enforced yet. See the field doc comments
+// below and CLAUDE.md's Design Debt section for what's stored-but-not-wired,
+// matching how this codebase already documents task.Priority/RetryConfig.
+package role
+
+// RoleConfig is one version of a role's configuration.
+type RoleConfig struct {
+	// Role names the role this config applies to (e.g. "coder", "reviewer").
+	Role string `json:"role"`
+
+	// SystemPrompt is appended to Agent.SystemPromptAppend when a task
+	// dispatches through this role (internal/executor.Pool.execute()). Wired.
+	SystemPrompt string `json:"system_prompt,omitempty"`
+
+	// Tools, SandboxKind, and DefaultBudgetUSD are stored and round-tripped
+	// through the API/storage layer but are NOT YET enforced by the executor:
+	// guardrails/tool availability are still applied uniformly by
+	// NativeRunner (Phase 3) regardless of role, and SandboxKind here has no
+	// effect on which sandbox.Sandbox implementation a runner picks (that's
+	// still purely provider-driven, see NativeRunner.SandboxKind). A later
+	// phase should thread these through. DefaultBudgetUSD is read by
+	// internal/scheduler as the estimated cost passed to
+	// budget.Accountant.Allow() when considering an escalation, which is a
+	// narrow, specific use — not general per-role budget enforcement at
+	// dispatch time.
+	Tools            []string `json:"tools,omitempty"`
+	SandboxKind      string   `json:"sandbox_kind,omitempty"`
+	DefaultBudgetUSD float64  `json:"default_budget_usd,omitempty"`
+
+	// EscalationLadder is the ordered list of tiers a role-typed task climbs
+	// on repeated failure. Tier 0 is used for the initial dispatch.
+	EscalationLadder []Tier `json:"escalation_ladder,omitempty"`
+}
+
+// Tier is one rung-group in an escalation ladder: a set of candidate
+// (provider, model) rungs to choose among, plus how many attempts may be made
+// at this tier before the scheduler escalates to the next one.
+type Tier struct {
+	Candidates []Rung `json:"candidates"`
+	// SelectionMode is "round_robin" (default, when empty) or "single" (always
+	// use Candidates[0]).
+	SelectionMode string `json:"selection_mode,omitempty"`
+	// MaxRetries is the number of attempts allowed at this tier before the
+	// scheduler escalates to the next tier. 0 means "escalate immediately
+	// after the first failure at this tier" (no retries held here).
+	MaxRetries int `json:"max_retries"`
+}
+
+// Rung is a single (provider, model) pair. Provider must match a registered
+// executor runner key: "local", "anthropic", "google", "groq", "openrouter",
+// "openai".
+type Rung struct {
+	Provider string `json:"provider"`
+	Model    string `json:"model"`
+}
+
+// EffectiveSelectionMode returns t.SelectionMode, defaulting to
+// "round_robin" when unset.
+func (t Tier) EffectiveSelectionMode() string {
+	if t.SelectionMode == "" {
+		return "round_robin"
+	}
+	return t.SelectionMode
+}
diff --git a/internal/role/role_test.go b/internal/role/role_test.go
new file mode 100644
index 0000000..6d2294e
--- /dev/null
+++ b/internal/role/role_test.go
@@ -0,0 +1,73 @@
+package role
+
+import (
+	"encoding/json"
+	"reflect"
+	"testing"
+)
+
+func TestRoleConfig_JSONRoundTrip(t *testing.T) {
+	rc := RoleConfig{
+		Role:             "coder",
+		SystemPrompt:     "You are a careful coding agent.",
+		Tools:            []string{"Bash", "Read", "Edit"},
+		SandboxKind:      "docker",
+		DefaultBudgetUSD: 1.5,
+		EscalationLadder: []Tier{
+			{
+				Candidates: []Rung{
+					{Provider: "local", Model: "llama3.1:8b"},
+				},
+				SelectionMode: "single",
+				MaxRetries:    2,
+			},
+			{
+				Candidates: []Rung{
+					{Provider: "groq", Model: "llama-3.3-70b-versatile"},
+					{Provider: "openrouter", Model: "meta-llama/llama-3.3-70b-instruct:free"},
+				},
+				SelectionMode: "round_robin",
+				MaxRetries:    1,
+			},
+			{
+				Candidates: []Rung{
+					{Provider: "anthropic", Model: "claude-sonnet-5"},
+				},
+				MaxRetries: 0,
+			},
+		},
+	}
+
+	b, err := json.Marshal(rc)
+	if err != nil {
+		t.Fatalf("Marshal: %v", err)
+	}
+
+	var got RoleConfig
+	if err := json.Unmarshal(b, &got); err != nil {
+		t.Fatalf("Unmarshal: %v", err)
+	}
+
+	if !reflect.DeepEqual(rc, got) {
+		t.Errorf("round trip mismatch:\n  want: %+v\n  got:  %+v", rc, got)
+	}
+}
+
+func TestTier_EffectiveSelectionMode(t *testing.T) {
+	cases := []struct {
+		name string
+		tier Tier
+		want string
+	}{
+		{"empty defaults to round_robin", Tier{}, "round_robin"},
+		{"explicit single", Tier{SelectionMode: "single"}, "single"},
+		{"explicit round_robin", Tier{SelectionMode: "round_robin"}, "round_robin"},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			if got := c.tier.EffectiveSelectionMode(); got != c.want {
+				t.Errorf("got %q, want %q", got, c.want)
+			}
+		})
+	}
+}