#18072: fix(Telegram): usage footer not sent to Telegram when blockStreaming is enabled (#17832)

## Summary When `blockStreaming: true` is set, the usage footer (`/usage full` or `/usage tokens`) never gets sent to the channel. TUI shows it fine, but Telegram/Discord/etc don't. Closes #17832 lobster-biscuit ## Root Cause `buildReplyPayloads` in `agent-runner-payloads.ts` sets `replyPayloads` to `[]` when block streaming succeeded (via `shouldDropFinalPayloads`). Back in `agent-runner.ts`, the `replyPayloads.length === 0` early return fires before the usage footer computation — so `appendUsageLine` is never reached. ## Changes - Before: usage footer computation happens after the empty-payloads early return — gets skipped when block streaming drops final payloads - After: usage footer is computed before the early return; if payloads are empty but a footer exists, it's sent as a standalone payload Only `agent-runner.ts` changed (code motion + 4 new lines at the early return). ## Tests - `agent-runner.misc.runreplyagent.test.ts` — 4 new tests covering the block streaming + usage footer interaction: - `responseUsage=full`: footer sent with session key - `responseUsage=tokens`: footer sent without session key - `responseUsage=off`: returns undefined, no footer - zero usage: returns undefined, no footer - All 4 fail before fix, pass after - All 386 tests in `src/auto-reply/reply/` pass <!-- greptile_comment --> <h3>Greptile Summary</h3> Fixes the bug where usage footers (`/usage full` or `/usage tokens`) were not sent to Telegram/Discord when `blockStreaming: true` is enabled. The fix moves the usage footer computation logic before the empty-payloads early return, allowing it to be sent as a standalone payload when block streaming drops final payloads. - Moved usage footer computation (lines 421-446) to execute before the `replyPayloads.length === 0` check - Added logic to send usage footer as standalone payload when block streaming succeeded but dropped final payloads (lines 450-451) - Added 4 comprehensive tests covering all usage footer scenarios with block streaming enabled <h3>Confidence Score: 5/5</h3> - This PR is safe to merge with minimal risk - The fix is a clean code motion that addresses the exact root cause described in the PR. The logic is moved from after the early return to before it, with a simple 4-line addition to handle the edge case. The change is well-tested with 4 new tests covering all scenarios (responseUsage=full/tokens/off, zero usage), and all 386 existing tests pass. - No files require special attention _{Last reviewed commit: 4917272} <!-- greptile_other_comments_section --> <!-- /greptile_comment -->