fix(T-34): record only the repos the trending digest actually delivered

[DamengRandom]

Closes #26

The bug

buildTrendingMessage drops trailing repos when the digest would exceed Telegram's 4096-char limit. That truncation is correct and stays — without it Telegram rejects the entire message, and news-telegram.test.ts:87 exists to pin it.

The bug is what happened afterwards. The drop was invisible outside the tool, which returned { success: true } either way, so runNewsAgent persisted the full, undropped list with sent = true:

const sent = await WorkCoordinator.sendTelegram(curated)   // true — the send did succeed
await WorkCoordinator.saveTrending(curated, sent, now)     // `curated`, not what was delivered

Repos that never appeared in the outgoing message were recorded as delivered. Since github_trending.sent is the only record of what went out, nothing afterwards could tell a delivered repo from a dropped one — and no log line mentioned it.

The fix

• fitRepos exposes which repos survived; buildTrendingMessage is now assemble(fitRepos(...)), so the message and the kept list can't disagree
• the tool returns the delivered names and logs a warning when it drops any
• saveTrending tags each repo individually with whether it was actually delivered

Verification

Ran the real tool against issue #26's own reproduction (8 repos with summaries that expand under HTML escaping), with fetch stubbed to capture the outgoing body:

curated handed to sendTelegram : 8
entries actually in the message: 4

  owner0/project-0       sent=true  delivered=true
  owner1/project-1       sent=true  delivered=true
  owner2/project-2       sent=true  delivered=true
  owner3/project-3       sent=true  delivered=true
  owner4/project-4       sent=false delivered=false
  owner5/project-5       sent=false delivered=false
  owner6/project-6       sent=false delivered=false
  owner7/project-7       sent=false delivered=false

rows recorded sent=true but never delivered: 0     (was 4)

The truncation is no longer silent:

WARN ✂️ Digest too long for Telegram — dropped 4 of 8 repos: owner4/project-4, owner5/project-5, owner6/project-6, owner7/project-7

• pnpm test — 73 pass (2 new), pnpm tsc and pnpm format:check clean

Worth a look during review

sendTelegram now returns Set<string> instead of boolean. A failed send returns an empty set, so nothing gets marked sent — same outcome as the old false, just carried differently.

Since a dropped repo is now saved with sent = false, it stays eligible to appear in a later digest rather than being silently written off. That seems right, but it is a behaviour change worth confirming.

🤖 Generated with Claude Code