feat: init mlkem project with Verilator test framework

- sync_rtl/common/: skid_buffer, pipeline_reg, defines (valid/ready)
- sync_rtl/mod_add/: modular adder example with Verilator C++ TB
- test_framework/: Python-driven Verilator compile/sim/compare pipeline
- test_framework/modules/mod_add/: 50-vector test plan, full鏈路 PASS
- .trellis/spec/: RTL and test_framework conventions documented

.opencode/plugins/session-start.js

@@ -0,0 +1,101 @@
+/* global process */
+/**
+ * Trellis Session Start Plugin
+ *
+ * Injects context when user sends the first message in a session.
+ * Uses OpenCode's chat.message hook directly so the context persists in history.
+ */
+
+import { TrellisContext, contextCollector, debugLog, isTrellisSubagent } from "../lib/trellis-context.js"
+import {
+  buildSessionContext,
+  hasPersistedInjectedContext,
+  markContextInjected,
+} from "../lib/session-utils.js"
+
+// OpenCode 1.2.x expects plugins to be factory functions (see inject-subagent-context.js comment).
+export default async ({ directory, client }) => {
+  const ctx = new TrellisContext(directory)
+  debugLog("session", "Plugin loaded, directory:", directory)
+
+  return {
+    event: ({ event }) => {
+      try {
+        if (event?.type === "session.compacted" && event?.properties?.sessionID) {
+          const sessionID = event.properties.sessionID
+          contextCollector.clear(sessionID)
+          debugLog("session", "Cleared processed flag after compaction for session:", sessionID)
+        }
+      } catch (error) {
+        debugLog(
+          "session",
+          "Error in event hook:",
+          error instanceof Error ? error.message : String(error),
+        )
+      }
+    },
+
+    // chat.message - triggered when user sends a message.
+    // Modify the message in-place so the context is persisted with updateMessage/updatePart.
+    "chat.message": async (input, output) => {
+      try {
+        const sessionID = input.sessionID
+        const agent = input.agent || "unknown"
+        debugLog("session", "chat.message called, sessionID:", sessionID, "agent:", agent)
+
+        // Skip Trellis sub-agent turns — sub-agent context is injected by
+        // `inject-subagent-context.js` on the parent's tool.execute.before;
+        // re-injecting the main-session SessionStart here would drown that.
+        if (isTrellisSubagent(input)) {
+          debugLog("session", "Skipping trellis subagent turn:", agent)
+          return
+        }
+
+        if (process.env.TRELLIS_HOOKS === "0" || process.env.TRELLIS_DISABLE_HOOKS === "1") {
+          debugLog("session", "Skipping - TRELLIS_HOOKS disabled")
+          return
+        }
+
+        if (process.env.OPENCODE_NON_INTERACTIVE === "1") {
+          debugLog("session", "Skipping - non-interactive mode")
+          return
+        }
+
+        if (contextCollector.isProcessed(sessionID)) {
+          debugLog("session", "Skipping - session already processed")
+          return
+        }
+
+        if (await hasPersistedInjectedContext(client, ctx.directory, sessionID)) {
+          contextCollector.markProcessed(sessionID)
+          debugLog("session", "Skipping - session already contains persisted Trellis context")
+          return
+        }
+
+        const context = buildSessionContext(ctx, input)
+        debugLog("session", "Built context, length:", context.length)
+
+        const parts = output?.parts || []
+        const textPartIndex = parts.findIndex(
+          p => p.type === "text" && p.text !== undefined
+        )
+
+        if (textPartIndex !== -1) {
+          const originalText = parts[textPartIndex].text || ""
+          parts[textPartIndex].text = `${context}\n\n---\n\n${originalText}`
+          markContextInjected(parts[textPartIndex])
+          debugLog("session", "Injected context into chat.message text part, length:", context.length)
+        } else {
+          const injectedPart = { type: "text", text: context }
+          markContextInjected(injectedPart)
+          parts.unshift(injectedPart)
+          debugLog("session", "Prepended new text part with context, length:", context.length)
+        }
+
+        contextCollector.markProcessed(sessionID)
+      } catch (error) {
+        debugLog("session", "Error in chat.message:", error.message, error.stack)
+      }
+    },
+  }
+}