fix: report the real cause when curation output fails to parse

src/agent/curator-graph.test.ts

@@ -59,3 +59,58 @@ test('gives up after exhausting retries — curated is null, not an empty array,
   assert.equal(result.curated, null)
   assert.ok(result.error, 'expected a validation error to be surfaced, not swallowed')
 })
+
+test('non-JSON output names the parse failure and includes the offending text, not a generic Zod null error', async () => {
+  const fakeCurate = async () => 'this is not json at all'
+
+  const result = await runCuratorGraph(sampleRepos, fakeCurate)
+
+  assert.equal(result.curated, null)
+  assert.match(result.error ?? '', /not valid JSON/)
+  assert.match(result.error ?? '', /this is not json at all/)
+})
+
+test('a long non-JSON response is truncated in the recorded error, with the original length reported', async () => {
+  const longRaw = 'x'.repeat(500)
+  const fakeCurate = async () => longRaw
+
+  const result = await runCuratorGraph(sampleRepos, fakeCurate)
+
+  assert.equal(result.curated, null)
+  assert.match(result.error ?? '', /500 chars/)
+  assert.ok((result.error ?? '').length < longRaw.length, 'expected the excerpt to be bounded, not a full raw dump')
+})
+
+test('well-formed JSON that fails the schema produces a distinguishably different error from a parse failure', async () => {
+  const fakeCurate = async () => JSON.stringify({ repos: [{ nope: true }] })
+
+  const result = await runCuratorGraph(sampleRepos, fakeCurate)
+
+  assert.equal(result.curated, null)
+  assert.match(result.error ?? '', /did not match the expected schema/)
+  assert.doesNotMatch(result.error ?? '', /not valid JSON/)
+})
+
+test('an exception thrown by curate() is caught and recorded instead of crashing the graph', async () => {
+  const fakeCurate = async () => {
+    throw new Error('rate limited')
+  }
+
+  const result = await runCuratorGraph(sampleRepos, fakeCurate)
+
+  assert.equal(result.curated, null)
+  assert.match(result.error ?? '', /curate\(\) threw/)
+  assert.match(result.error ?? '', /rate limited/)
+})
+
+test('a non-Error value thrown by curate() is still stringified into the recorded error', async () => {
+  const fakeCurate = async () => {
+    throw 'connection reset'
+  }
+
+  const result = await runCuratorGraph(sampleRepos, fakeCurate)
+
+  assert.equal(result.curated, null)
+  assert.match(result.error ?? '', /curate\(\) threw/)
+  assert.match(result.error ?? '', /connection reset/)
+})

src/agent/curator.graph.ts

@@ -2,7 +2,7 @@ import { StateGraph, StateSchema, START, END } from '@langchain/langgraph'
 import { z } from 'zod'
 import { TrendingRepoOutputSchema, type CuratedRepo } from '../schemas/index.js'
 
-import { parseJson } from './utils.ts'
+import { truncate } from './utils.ts'
 import { TrendingRepo } from '../schemas/index.ts'
 
 const CuratedRepoOutputSchema = z.object({ repos: z.array(TrendingRepoOutputSchema) })
@@ -11,6 +11,7 @@ export type CurateFn = (repos: TrendingRepo[], feedback?: string) => Promise<str
 export type CuratorResult = { curated: CuratedRepo[] | null; error: string | null }
 
 const MAX_ATTEMPTS = 2
+const EXCERPT_MAX = 300
 
 const CuratorState = new StateSchema({
   repos: z.custom<TrendingRepo[]>(),
@@ -19,16 +20,37 @@ const CuratorState = new StateSchema({
   attempts: z.custom<number>(),
 })
 
-export async function runCuratorGraph(repos: TrendingRepo[], curate: CurateFn): Promise<CuratorResult> {
-  const graph = new StateGraph(CuratorState)
-    .addNode('curate', async (state) => {
-      const raw = await curate(state.repos, state.error || undefined)
-      const parsed = CuratedRepoOutputSchema.safeParse(parseJson<unknown>(raw, null))
+function errorMessage(err: unknown): string {
+  return err instanceof Error ? err.message : String(err)
+}
 
-      if (parsed.success) return { curated: parsed.data.repos, error: null }
+async function curateNode(state: { repos: TrendingRepo[]; error: string | null; attempts: number }, curate: CurateFn) {
+  let raw: string
+  try {
+    raw = await curate(state.repos, state.error || undefined)
+  } catch (err) {
+    return { error: `curate() threw: ${errorMessage(err)}`, attempts: state.attempts + 1 }
+  }
+
+  let json: unknown
+  try {
+    json = JSON.parse(raw)
+  } catch (err) {
+    return {
+      error: `curator output was not valid JSON (${errorMessage(err)}) — ${raw.length} chars: ${truncate(raw, EXCERPT_MAX)}`,
+      attempts: state.attempts + 1,
+    }
+  }
+
+  const parsed = CuratedRepoOutputSchema.safeParse(json)
+  if (parsed.success) return { curated: parsed.data.repos, error: null }
+
+  return { error: `curator output did not match the expected schema: ${parsed.error.message}`, attempts: state.attempts + 1 }
+}
 
-      return { error: parsed.error.message, attempts: state.attempts + 1 }
-    })
+export async function runCuratorGraph(repos: TrendingRepo[], curate: CurateFn): Promise<CuratorResult> {
+  const graph = new StateGraph(CuratorState)
+    .addNode('curate', (state) => curateNode(state, curate))
     .addEdge(START, 'curate')
     .addConditionalEdges('curate', (state) => (state.curated || state.attempts >= MAX_ATTEMPTS ? END : 'curate'))
     .compile()

src/agent/index.ts

@@ -175,13 +175,7 @@ export class WorkCoordinator {
   private static async curateRepos(newRepos: TrendingRepo[], feedback?: string): Promise<string> {
     logger.info('⚡️ Writing digest summaries...')
 
-    try {
-      return await curateTrending(newRepos, feedback)
-    } catch (err) {
-      logger.error({ err }, '❌ Trending curation attempt failed')
-
-      return ''
-    }
+    return curateTrending(newRepos, feedback)
   }
 
   // Step 4: deliver the digest via Telegram. Returns whether the send succeeded.