feat: add pagination to miner PRs and issues endpoints

packages/das/src/api/miners/miners.controller.ts

@@ -122,13 +122,27 @@ export class MinersController {
     description:
       "ISO timestamp. Defaults to 35 days ago (midnight UTC) if omitted.",
   })
+  @ApiQuery({
+    name: "cursor",
+    required: false,
+    description: "Opaque pagination cursor.",
+  })
+  @ApiQuery({
+    name: "limit",
+    required: false,
+    description: "Max results (default 50, max 200).",
+  })
   async getPullRequests(
     @Param("githubId") githubId: string,
     @Query("since") since?: string,
+    @Query("cursor") cursor?: string,
+    @Query("limit") limit?: string,
   ): Promise<unknown> {
     return this.miners.getPullRequests(
       githubId,
       MinersService.resolveSince(since),
+      cursor,
+      limit ? parseInt(limit, 10) : undefined,
     );
   }
 
@@ -169,11 +183,28 @@ export class MinersController {
       "ISO timestamp. When omitted, the response contains all currently-" +
       "OPEN issues with no time bound and no CLOSED history.",
   })
+  @ApiQuery({
+    name: "cursor",
+    required: false,
+    description: "Opaque pagination cursor.",
+  })
+  @ApiQuery({
+    name: "limit",
+    required: false,
+    description: "Max results (default 50, max 200).",
+  })
   async getIssues(
     @Param("githubId") githubId: string,
     @Query("since") since?: string,
+    @Query("cursor") cursor?: string,
+    @Query("limit") limit?: string,
   ): Promise<unknown> {
-    return this.miners.getIssues(githubId, since ?? null);
+    return this.miners.getIssues(
+      githubId,
+      since ?? null,
+      cursor,
+      limit ? parseInt(limit, 10) : undefined,
+    );
   }
 
   @Post(":githubId/issues")

packages/das/src/api/miners/miners.service.ts

@@ -3,6 +3,20 @@ import { Injectable } from "@nestjs/common";
 import { DataSource } from "typeorm";
 
 const DEFAULT_SINCE_DAYS = 35;
+const DEFAULT_LIMIT = 50;
+const MAX_LIMIT = 200;
+
+interface PullRequestCursor {
+  created_at: string;
+  repo_full_name: string;
+  pr_number: number;
+}
+
+interface IssueCursor {
+  created_at: string;
+  repo_full_name: string;
+  issue_number: number;
+}
 
 // Column list (everything between SELECT and FROM) for the PR query. Shared by
 // the scalar-`since` GET path and the per-repo `since` POST path so the two
@@ -164,16 +178,85 @@ const ISSUE_SELECT_COLUMNS = `
 export class MinersService {
   constructor(private readonly dataSource: DataSource) {}
 
+  private encodeCursor(cursor: PullRequestCursor | IssueCursor): string {
+    return Buffer.from(JSON.stringify(cursor)).toString("base64");
+  }
+
+  private decodePullRequestCursor(cursor: string): PullRequestCursor | null {
+    try {
+      const decoded = JSON.parse(
+        Buffer.from(cursor, "base64").toString("utf-8"),
+      );
+      if (
+        decoded.created_at &&
+        decoded.repo_full_name &&
+        typeof decoded.pr_number === "number"
+      ) {
+        return decoded as PullRequestCursor;
+      }
+      return null;
+    } catch {
+      return null;
+    }
+  }
+
+  private decodeIssueCursor(cursor: string): IssueCursor | null {
+    try {
+      const decoded = JSON.parse(
+        Buffer.from(cursor, "base64").toString("utf-8"),
+      );
+      if (
+        decoded.created_at &&
+        decoded.repo_full_name &&
+        typeof decoded.issue_number === "number"
+      ) {
+        return decoded as IssueCursor;
+      }
+      return null;
+    } catch {
+      return null;
+    }
+  }
+
   async getPullRequests(
     githubId: string,
     since: string,
+    cursor?: string,
+    limit?: number,
   ): Promise<{
     github_id: string;
     since: string;
     generated_at: string;
     pull_requests: unknown[];
+    next_cursor: string | null;
   }> {
-    const rows = await this.dataSource.query(
+    const effectiveLimit = Math.min(limit ?? DEFAULT_LIMIT, MAX_LIMIT);
+    const decodedCursor = cursor ? this.decodePullRequestCursor(cursor) : null;
+
+    const params: (string | number)[] = [githubId, since];
+    let keysetClause = "";
+
+    if (decodedCursor) {
+      keysetClause = `
+        AND (
+          p.created_at < $3
+          OR (p.created_at = $3 AND p.repo_full_name < $4)
+          OR (p.created_at = $3 AND p.repo_full_name = $4 AND p.pr_number < $5)
+        )
+      `;
+      params.push(
+        decodedCursor.created_at,
+        decodedCursor.repo_full_name,
+        decodedCursor.pr_number,
+      );
+    }
+
+    const rows: Array<{
+      repo_full_name: string;
+      pr_number: number;
+      created_at: string;
+      [key: string]: unknown;
+    }> = await this.dataSource.query(
       `
       SELECT${PR_SELECT_COLUMNS}
       FROM pull_requests p
@@ -188,16 +271,30 @@ export class MinersService {
           OR (p.state = 'MERGED' AND p.merged_at >= $2)
           OR (p.state = 'CLOSED' AND p.created_at >= $2)
         )
-      ORDER BY p.created_at DESC
+        ${keysetClause}
+      ORDER BY p.created_at DESC, p.repo_full_name DESC, p.pr_number DESC
+      LIMIT ${effectiveLimit + 1}
       `,
-      [githubId, since],
+      params,
     );
 
+    const hasMore = rows.length > effectiveLimit;
+    const results = hasMore ? rows.slice(0, effectiveLimit) : rows;
+    const nextCursor =
+      hasMore && results.length > 0
+        ? this.encodeCursor({
+            created_at: results[results.length - 1].created_at,
+            repo_full_name: results[results.length - 1].repo_full_name,
+            pr_number: results[results.length - 1].pr_number,
+          })
+        : null;
+
     return {
       github_id: githubId,
       since,
       generated_at: new Date().toISOString(),
-      pull_requests: rows,
+      pull_requests: results,
+      next_cursor: nextCursor,
     };
   }
 
@@ -253,13 +350,42 @@ export class MinersService {
   async getIssues(
     githubId: string,
     since: string | null,
+    cursor?: string,
+    limit?: number,
   ): Promise<{
     github_id: string;
     since: string | null;
     generated_at: string;
     issues: unknown[];
+    next_cursor: string | null;
   }> {
-    const rows = await this.dataSource.query(
+    const effectiveLimit = Math.min(limit ?? DEFAULT_LIMIT, MAX_LIMIT);
+    const decodedCursor = cursor ? this.decodeIssueCursor(cursor) : null;
+
+    const params: (string | number | null)[] = [githubId, since];
+    let keysetClause = "";
+
+    if (decodedCursor) {
+      keysetClause = `
+        AND (
+          i.created_at < $3
+          OR (i.created_at = $3 AND i.repo_full_name < $4)
+          OR (i.created_at = $3 AND i.repo_full_name = $4 AND i.issue_number < $5)
+        )
+      `;
+      params.push(
+        decodedCursor.created_at,
+        decodedCursor.repo_full_name,
+        decodedCursor.issue_number,
+      );
+    }
+
+    const rows: Array<{
+      repo_full_name: string;
+      issue_number: number;
+      created_at: string;
+      [key: string]: unknown;
+    }> = await this.dataSource.query(
       `
       SELECT${ISSUE_SELECT_COLUMNS}
       FROM issues i
@@ -268,16 +394,30 @@ export class MinersService {
           (i.state = 'OPEN' AND ($2::timestamptz IS NULL OR i.created_at >= $2))
           OR (i.state = 'CLOSED' AND i.closed_at >= $2)
         )
-      ORDER BY i.created_at DESC
+        ${keysetClause}
+      ORDER BY i.created_at DESC, i.repo_full_name DESC, i.issue_number DESC
+      LIMIT ${effectiveLimit + 1}
       `,
-      [githubId, since],
+      params,
     );
 
+    const hasMore = rows.length > effectiveLimit;
+    const results = hasMore ? rows.slice(0, effectiveLimit) : rows;
+    const nextCursor =
+      hasMore && results.length > 0
+        ? this.encodeCursor({
+            created_at: results[results.length - 1].created_at,
+            repo_full_name: results[results.length - 1].repo_full_name,
+            issue_number: results[results.length - 1].issue_number,
+          })
+        : null;
+
     return {
       github_id: githubId,
       since,
       generated_at: new Date().toISOString(),
-      issues: rows,
+      issues: results,
+      next_cursor: nextCursor,
     };
   }