refactor(kernel): rename tabId → conversationId across contracts + consumers (218 tests)

Step 4 of the post-MVP backlog: resolve the last vocab drift. The canonical
term for a thread of turns is `conversationId` (GLOSSARY), but `AgentEvent`
variants and `RunTurnInput` still used the legacy `tabId` from the old frontend
"tab" concept, with session-orchestrator bridging `conversationId → tabId`.

Atomic, type-driven rename across the full 10-file consumer set:
- contracts/events.ts: all 11 AgentEvent variants tabId → conversationId
- contracts/runtime.ts: RunTurnInput.tabId → conversationId
- runtime/{events,run-turn,dispatch}.ts: factory params, ctx field, locals
- session-orchestrator: drop the redundant `tabId: conversationId` bridge line
- transport-http: emit wiring; external /chat field + X-Conversation-Id header
  unchanged (already canonical) — only the emitted NDJSON event field flips
- tests (run-turn, app, logic): inputs + assertions now use conversationId

Pure rename, zero behavior change: typecheck clean, 218 tests pass (unchanged
count), biome clean, `grep tabId packages/` → zero matches. Verified live:
multi-turn curl emits conversationId-keyed NDJSON and threads history correctly.
GLOSSARY drift note removed. Closes the post-MVP backlog (Steps 1–4).

1 files changed, 19 insertions, 15 deletions

diff --git a/packages/kernel/src/runtime/events.ts b/packages/kernel/src/runtime/events.ts
index 62218be..2a92008 100644
--- a/packages/kernel/src/runtime/events.ts
+++ b/packages/kernel/src/runtime/events.ts
@@ -1,57 +1,61 @@
 import type { AgentEvent } from "../contracts/events.js";
 import type { Usage } from "../contracts/provider.js";
 
-export function textDeltaEvent(tabId: string, turnId: string, delta: string): AgentEvent {
-	return { type: "text-delta", tabId, turnId, delta };
+export function textDeltaEvent(conversationId: string, turnId: string, delta: string): AgentEvent {
+	return { type: "text-delta", conversationId, turnId, delta };
 }
 
-export function reasoningDeltaEvent(tabId: string, turnId: string, delta: string): AgentEvent {
-	return { type: "reasoning-delta", tabId, turnId, delta };
+export function reasoningDeltaEvent(
+	conversationId: string,
+	turnId: string,
+	delta: string,
+): AgentEvent {
+	return { type: "reasoning-delta", conversationId, turnId, delta };
 }
 
 export function toolCallEvent(
-	tabId: string,
+	conversationId: string,
 	turnId: string,
 	toolCallId: string,
 	toolName: string,
 	input: unknown,
 ): AgentEvent {
-	return { type: "tool-call", tabId, turnId, toolCallId, toolName, input };
+	return { type: "tool-call", conversationId, turnId, toolCallId, toolName, input };
 }
 
 export function toolResultEvent(
-	tabId: string,
+	conversationId: string,
 	turnId: string,
 	toolCallId: string,
 	toolName: string,
 	content: string,
 	isError: boolean,
 ): AgentEvent {
-	return { type: "tool-result", tabId, turnId, toolCallId, toolName, content, isError };
+	return { type: "tool-result", conversationId, turnId, toolCallId, toolName, content, isError };
 }
 
 export function toolOutputEvent(
-	tabId: string,
+	conversationId: string,
 	turnId: string,
 	toolCallId: string,
 	data: string,
 	stream: "stdout" | "stderr",
 ): AgentEvent {
-	return { type: "tool-output", tabId, turnId, toolCallId, data, stream };
+	return { type: "tool-output", conversationId, turnId, toolCallId, data, stream };
 }
 
-export function usageEvent(tabId: string, turnId: string, usage: Usage): AgentEvent {
-	return { type: "usage", tabId, turnId, usage };
+export function usageEvent(conversationId: string, turnId: string, usage: Usage): AgentEvent {
+	return { type: "usage", conversationId, turnId, usage };
 }
 
 export function errorEvent(
-	tabId: string,
+	conversationId: string,
 	turnId: string,
 	message: string,
 	code?: string,
 ): AgentEvent {
 	if (code !== undefined) {
-		return { type: "error", tabId, turnId, message, code };
+		return { type: "error", conversationId, turnId, message, code };
 	}
-	return { type: "error", tabId, turnId, message };
+	return { type: "error", conversationId, turnId, message };
 }