feat: Phase 1 — modular backend architecture (v4.0-alpha)

Internal refactor: extract BackendAdapter, ModelRegistry, AgentRouter, SessionManager, and StatsCollector as standalone modules. Claude CLI logic encapsulated in ClaudeCliAdapter. External API completely unchanged — all existing endpoints behave identically. Legacy request path (callClaude/callClaudeStreaming) untouched. v4 modules load in parallel for validation. New endpoints: GET /backends — backend health and status GET /routing — agent routing table Architecture: unified-chunk.mjs — streaming protocol (delta/done/error) backends/base.mjs — BackendAdapter interface backends/claude-cli.mjs — Claude CLI adapter (core) model-registry.mjs — model → backend mapping (Layer 1) agent-router.mjs — agent policy routing (Layer 2) session-manager.mjs — conversation session management stats-collector.mjs — per-model/backend/agent metrics Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-07-21 21:15:09 +00:00 · 2026-03-25 08:02:53 +10:00
parent f6f4f68ecd
commit 1f1b3871da
9 changed files with 1639 additions and 6 deletions
@@ -0,0 +1,99 @@
+/**
+ * Model Registry — Layer 1 of OCP routing.
+ *
+ * Static mapping: model ID → backend ID.
+ * This is infrastructure, not policy. Every model must map to exactly one backend.
+ *
+ * Non-agent callers (Cline, Aider, etc.) only send a model name — this module
+ * is the only thing that tells OCP where to route the request.
+ */
+
+export class ModelRegistry {
+  constructor() {
+    /** @type {Map<string, {backendId: string, canonical: string}>} */
+    this._models = new Map();
+
+    /** @type {Map<string, Object>} model id → display metadata */
+    this._metadata = new Map();
+  }
+
+  /**
+   * Register models from a backend adapter.
+   * Called during startup for each enabled backend.
+   *
+   * @param {import("./backends/base.mjs").BackendAdapter} adapter
+   */
+  registerBackend(adapter) {
+    for (const modelId of adapter.models) {
+      this._models.set(modelId, {
+        backendId: adapter.id,
+        canonical: modelId,
+      });
+      this._metadata.set(modelId, {
+        backendId: adapter.id,
+        backendName: adapter.displayName,
+        tier: adapter.tier,
+        costType: adapter.costType,
+      });
+    }
+
+    // Also register aliases if the adapter supports resolveModel
+    if (typeof adapter.resolveModel === "function") {
+      // We don't auto-register aliases here — they're handled by
+      // supportsModel() on the adapter. The registry only knows canonical IDs.
+    }
+  }
+
+  /**
+   * Look up which backend serves a given model.
+   *
+   * @param {string} model — model ID (could be canonical or alias)
+   * @returns {{backendId: string, canonical: string} | null}
+   */
+  resolve(model) {
+    // Direct lookup first
+    const direct = this._models.get(model);
+    if (direct) return direct;
+
+    // No alias resolution here — that's the adapter's job.
+    // The router will ask each adapter if it supports the model.
+    return null;
+  }
+
+  /**
+   * Get all registered models with metadata.
+   * Used by GET /v1/models endpoint.
+   */
+  listModels() {
+    const result = [];
+    for (const [id, meta] of this._metadata) {
+      result.push({ id, ...meta });
+    }
+    return result;
+  }
+
+  /**
+   * Check if a model is known to the registry.
+   */
+  has(model) {
+    return this._models.has(model);
+  }
+
+  /**
+   * Get the backend ID for a model, or null.
+   */
+  getBackendId(model) {
+    return this._models.get(model)?.backendId || null;
+  }
+
+  /**
+   * Get all models for a specific backend.
+   */
+  getModelsForBackend(backendId) {
+    const models = [];
+    for (const [id, entry] of this._models) {
+      if (entry.backendId === backendId) models.push(id);
+    }
+    return models;
+  }
+}