Add thinking placeholder and improve location parameter handling

- Post '_Sea Haven Assistant is thinking..._' immediately on receipt,
  then update the message with the real response (chat.update)
- Broaden Maps location parameter description so agent passes facility
  names like 'Amazon BFI9' directly to Google Maps rather than asking
  the user to provide a street address

lambda/slack-processor/index.ts

@@ -41,7 +41,7 @@ async function postToSlack(
   channel: string,
   text: string,
   threadTs?: string,
-): Promise<void> {
+): Promise<string> {
   const body: Record<string, string> = { channel, text };
   if (threadTs) body.thread_ts = threadTs;
 
@@ -55,8 +55,29 @@ async function postToSlack(
   });
 
   if (!res.ok) throw new Error(`Slack HTTP error ${res.status}`);
-  const data = (await res.json()) as { ok: boolean; error?: string };
+  const data = (await res.json()) as { ok: boolean; ts?: string; error?: string };
   if (!data.ok) throw new Error(`Slack API error: ${data.error}`);
+  return data.ts!;
+}
+
+async function updateSlack(
+  token: string,
+  channel: string,
+  ts: string,
+  text: string,
+): Promise<void> {
+  const res = await fetch('https://slack.com/api/chat.update', {
+    method: 'POST',
+    headers: {
+      'Content-Type': 'application/json',
+      Authorization: `Bearer ${token}`,
+    },
+    body: JSON.stringify({ channel, ts, text }),
+  });
+
+  if (!res.ok) throw new Error(`Slack HTTP error ${res.status}`);
+  const data = (await res.json()) as { ok: boolean; error?: string };
+  if (!data.ok) throw new Error(`Slack update error: ${data.error}`);
 }
 
 // Reuse the most recent Bedrock session if there's been activity in the last 30 minutes.
@@ -113,6 +134,14 @@ export const handler = async (event: ProcessorEvent): Promise<void> => {
     resolveSessionId(userId),
   ]);
 
+  // Post placeholder immediately so the user sees a response while the agent thinks
+  const placeholderTs = await postToSlack(
+    credentials.botToken,
+    channelId,
+    '_Sea Haven Assistant is thinking..._',
+    threadTs ?? ts,
+  );
+
   let answer: string;
   try {
     answer = await invokeAgent(sessionId, text);
@@ -121,7 +150,7 @@ export const handler = async (event: ProcessorEvent): Promise<void> => {
     answer = 'Sorry, I encountered an error processing your request. Please try again in a moment.';
   }
 
-  await postToSlack(credentials.botToken, channelId, answer, threadTs ?? ts);
+  await updateSlack(credentials.botToken, channelId, placeholderTs, answer);
 
   const now = new Date().toISOString();
   const ttl = Math.floor(Date.now() / 1000) + 90 * 24 * 60 * 60; // 90-day TTL

lib/constructs/bedrock-agent.ts

@@ -189,7 +189,7 @@ Keep responses concise, professional, and actionable.`;
                   },
                   location: {
                     type: 'string',
-                    description: 'City, address, or area to search near (e.g., "Seattle WA", "Chicago IL")',
+                    description: 'Location to search near — can be a city, address, zip code, or facility/business name (e.g., "Seattle WA", "Amazon BFI9", "3230 International Pl DuPont WA"). Pass whatever location context the user provided; Google Maps will resolve it.',
                     required: true,
                   },
                 },
@@ -205,7 +205,7 @@ Keep responses concise, professional, and actionable.`;
     this.agentAlias = new bedrock.CfnAgentAlias(this, 'AgentAlias', {
       agentId: this.agent.attrAgentId,
       agentAliasName: 'live',
-      description: 'Production alias — seahaven-assistant v2 (Claude Sonnet 4.5)',
+      description: 'Production alias — seahaven-assistant v3 (flexible location lookup)',
     });
   }
 }