refactor: rename 'tier' to 'level' across the codebase

- Updated WorkerState type to use 'level' instead of 'tier'.
- Modified functions related to worker state management, including parseWorkerState, emptyWorkerState, getSessionForLevel, activateWorker, and deactivateWorker to reflect the new terminology.
- Adjusted health check logic to utilize 'level' instead of 'tier'.
- Refactored tick and setup tools to accommodate the change from 'tier' to 'level', including model configuration and workspace scaffolding.
- Updated tests to ensure consistency with the new 'level' terminology.
- Revised documentation and comments to reflect the changes in terminology from 'tier' to 'level'.

lib/tiers.ts

@@ -1,17 +1,16 @@
 /**
- * Developer tier definitions and model resolution.
+ * Developer level definitions and model resolution.
  *
- * Tier names always include the role prefix: "dev.junior", "qa.reviewer", etc.
- * This makes tier names globally unique and self-documenting.
+ * Level names are plain: "junior", "senior", "reviewer", etc.
+ * Role context (dev/qa) is always provided by the caller or parent structure.
  */
 
-export const DEV_TIERS = ["dev.junior", "dev.medior", "dev.senior"] as const;
-export const QA_TIERS = ["qa.reviewer", "qa.tester"] as const;
-export const ALL_TIERS = [...DEV_TIERS, ...QA_TIERS] as const;
+export const DEV_LEVELS = ["junior", "medior", "senior"] as const;
+export const QA_LEVELS = ["reviewer", "tester"] as const;
 
-export type DevTier = (typeof DEV_TIERS)[number];
-export type QaTier = (typeof QA_TIERS)[number];
-export type Tier = (typeof ALL_TIERS)[number];
+export type DevLevel = (typeof DEV_LEVELS)[number];
+export type QaLevel = (typeof QA_LEVELS)[number];
+export type Level = DevLevel | QaLevel;
 
 /** Default models, nested by role. */
 export const DEFAULT_MODELS = {
@@ -27,7 +26,7 @@ export const DEFAULT_MODELS = {
 };
 
 /** Emoji used in announcements, nested by role. */
-export const TIER_EMOJI = {
+export const LEVEL_EMOJI = {
   dev: {
     junior: "⚡",
     medior: "🔧",
@@ -39,77 +38,52 @@ export const TIER_EMOJI = {
   },
 };
 
-/** Check if a string is a valid tier name. */
-export function isTier(value: string): value is Tier {
-  return (ALL_TIERS as readonly string[]).includes(value);
+/** Check if a level belongs to the dev role. */
+export function isDevLevel(value: string): value is DevLevel {
+  return (DEV_LEVELS as readonly string[]).includes(value);
 }
 
-/** Check if a tier belongs to the dev role. */
-export function isDevTier(value: string): value is DevTier {
-  return (DEV_TIERS as readonly string[]).includes(value);
+/** Check if a level belongs to the qa role. */
+export function isQaLevel(value: string): value is QaLevel {
+  return (QA_LEVELS as readonly string[]).includes(value);
 }
 
-/** Extract the role from a tier name (e.g. "dev.junior" → "dev"). */
-export function tierRole(tier: string): "dev" | "qa" | undefined {
-  if (tier.startsWith("dev.")) return "dev";
-  if (tier.startsWith("qa.")) return "qa";
+/** Determine the role a level belongs to. */
+export function levelRole(level: string): "dev" | "qa" | undefined {
+  if (isDevLevel(level)) return "dev";
+  if (isQaLevel(level)) return "qa";
   return undefined;
 }
 
-/** Extract the short name from a tier (e.g. "dev.junior" → "junior"). */
-export function tierName(tier: string): string {
-  const dot = tier.indexOf(".");
-  return dot >= 0 ? tier.slice(dot + 1) : tier;
+/** Get the default model for a role + level. */
+export function defaultModel(role: "dev" | "qa", level: string): string | undefined {
+  return (DEFAULT_MODELS[role] as Record<string, string>)[level];
 }
 
-/** Look up a value from a nested role structure using a full tier name. */
-function lookupNested<T>(map: Record<string, Record<string, T>>, tier: string): T | undefined {
-  const role = tierRole(tier);
-  if (!role) return undefined;
-  return map[role]?.[tierName(tier)];
-}
-
-/** Get the default model for a tier. */
-export function defaultModel(tier: string): string | undefined {
-  return lookupNested(DEFAULT_MODELS, tier);
-}
-
-/** Get the emoji for a tier. */
-export function tierEmoji(tier: string): string | undefined {
-  return lookupNested(TIER_EMOJI, tier);
-}
-
-/** Build a flat Record<Tier, string> of all default models. */
-export function allDefaultModels(): Record<Tier, string> {
-  const result = {} as Record<Tier, string>;
-  for (const tier of ALL_TIERS) {
-    result[tier] = defaultModel(tier)!;
-  }
-  return result;
+/** Get the emoji for a role + level. */
+export function levelEmoji(role: "dev" | "qa", level: string): string | undefined {
+  return (LEVEL_EMOJI[role] as Record<string, string>)[level];
 }
 
 /**
- * Resolve a tier name to a full model ID.
+ * Resolve a level to a full model ID.
  *
  * Resolution order:
- * 1. Parse "role.name" → look up config `models.<role>.<name>`
- * 2. DEFAULT_MODELS[role][name]
+ * 1. Plugin config `models.<role>.<level>`
+ * 2. DEFAULT_MODELS[role][level]
  * 3. Passthrough (treat as raw model ID)
  */
-export function resolveTierToModel(
-  tier: string,
+export function resolveModel(
+  role: "dev" | "qa",
+  level: string,
   pluginConfig?: Record<string, unknown>,
 ): string {
   const models = (pluginConfig as { models?: Record<string, unknown> })?.models;
 
   if (models && typeof models === "object") {
-    const role = tierRole(tier);
-    const name = tierName(tier);
-    if (role) {
-      const roleModels = models[role] as Record<string, string> | undefined;
-      if (roleModels?.[name]) return roleModels[name];
-    }
+    const roleModels = models[role] as Record<string, string> | undefined;
+    if (roleModels?.[level]) return roleModels[level];
   }
 
-  return defaultModel(tier) ?? tier;
+  return defaultModel(role, level) ?? level;
 }