feat(session): add ts_before and breakpoint params to Session.messages API

Add optional parameters to Session.messages() for loading older messages:
- ts_before: filter to messages created before this timestamp
- breakpoint: stop at first compaction summary when true

This is a foundational API enhancement that enables clients to implement
pagination and history loading without breaking existing functionality.

Author: ryanwyler

packages/opencode/src/server/routes/session.ts

@@ -567,13 +567,17 @@ export const SessionRoutes = lazy(() =>
         "query",
         z.object({
           limit: z.coerce.number().optional(),
+          ts_before: z.coerce.number().optional(),
+          breakpoint: z.coerce.boolean().optional(),
         }),
       ),
       async (c) => {
         const query = c.req.valid("query")
         const messages = await Session.messages({
           sessionID: c.req.valid("param").sessionID,
           limit: query.limit,
+          ts_before: query.ts_before,
+          breakpoint: query.breakpoint,
         })
         return c.json(messages)
       },

packages/opencode/src/session/index.ts

@@ -293,12 +293,16 @@ export namespace Session {
     z.object({
       sessionID: Identifier.schema("session"),
       limit: z.number().optional(),
+      ts_before: z.number().optional(),
+      breakpoint: z.boolean().optional(),
     }),
     async (input) => {
       const result = [] as MessageV2.WithParts[]
       for await (const msg of MessageV2.stream(input.sessionID)) {
+        if (input.ts_before && msg.info.time.created >= input.ts_before) continue
         if (input.limit && result.length >= input.limit) break
         result.push(msg)
+        if (input.ts_before && input.breakpoint && msg.parts.some((p) => p.type === "compaction")) break
       }
       result.reverse()
       return result