fix: main build has only PASSED proposals

common.ts

@@ -1,6 +1,7 @@
 #!/usr/bin/env tsx
 // @ts-check
 
+import assert from 'node:assert';
 import fs from 'node:fs';
 import * as path from 'node:path';
 
@@ -44,6 +45,13 @@ export function readProposals(): ProposalInfo[] {
   return proposalPaths.map(readInfo);
 }
 
+export function lastPassedProposal(proposals: ProposalInfo[]): ProposalInfo {
+  // @ts-expect-error use es2023; findLast is available in Node 18
+  const last = proposals.findLast(p => p.proposalIdentifier.match(/^\d/));
+  assert(last, 'no passed proposals');
+  return last;
+}
+
 export function imageNameForProposalTest(proposal) {
   const target = `test-${proposal.proposalName}`;
   return {

makeDockerfile.ts

@@ -3,7 +3,7 @@
 
 import assert from 'node:assert';
 import fs from 'node:fs';
-import { readProposals } from './common';
+import { lastPassedProposal, readProposals } from './common';
 import type {
   ProposalInfo,
   SoftwareUpgradeProposal,
@@ -177,8 +177,9 @@ ENTRYPOINT ./start_agd.sh
 // The upgrade doesn't happen until the next stage begins executing.
 const blocks: string[] = [];
 
+const allProposals = readProposals();
 let previousProposal: ProposalInfo | null = null;
-for (const proposal of readProposals()) {
+for (const proposal of allProposals) {
   //   UNTIL region support https://github.com/microsoft/vscode-docker/issues/230
   blocks.push(
     `#----------------\n# ${proposal.proposalName}\n#----------------`,
@@ -202,7 +203,7 @@ for (const proposal of readProposals()) {
   blocks.push(stage.TEST(proposal));
   previousProposal = proposal;
 }
-blocks.push(stage.DEFAULT(previousProposal!));
+blocks.push(stage.DEFAULT(lastPassedProposal(allProposals)));
 
 export function refreshDockerfile() {
   const contents = blocks.join('\n');