fix(gateway): rewind MarkdownV2-escaped pipe tables in cron Telegram deliveries

[Kewe63]

Summary

Fixes the broken-Telegram-table symptom from cron jobs that instruct the agent to emit MarkdownV2 tables (#53632). The model emits pipe-table rows already-escaped (\| instead of |), and Telegram's MarkdownV2 renderer prints the backslashes verbatim — the recipient sees literal \| instead of a native Telegram table render.

This PR adds a scoped unescape guard in DeliveryRouter._deliver_to_platform that detects cron-routed Telegram deliveries (metadata.job_id) carrying a MarkdownV2-escaped pipe-table, and rewinds \| → | inside those table rows. The downstream adapter's normal MarkdownV2 escape re-applies once and Telegram renders the table natively.

---

Problem

Reporter (daily-news cron delivered to Telegram) saw tables render as escaped-pipe rows:

📅 2-Week Forward Calendar
\| Date \| Event \| Category \| Expected Impact \|
\|:-----\|:------\|:---------\|:----------------\|
\| 2026-07-15 \| Fed Beige Book \| Macro \| Regional growth \|

instead of a Telegram-rendered table. The full copy in chat history / session view showed the table correctly — only the final Telegram send was broken.

Root cause: when the model interprets a prompt as "use Telegram MarkdownV2 syntax", it pre-escapes the pipe bars itself. The Telegram adapter's format_message() then re-applies MarkdownV2 escape on top, producing double-escaped output (\\|) which MarkdownV2 renders as the escaped literal \|.

---

Fix

Detect-then-rewind helpers in gateway/delivery.py:

_MARKDOWNV2_ESCAPED_TABLE_BAR = re.compile(r'\\\|')

def _looks_like_cron_markdownv2_table(content: Optional[str]) -> bool:
    """Conservative shape check: >= 2 pipe-table-shaped rows AND >= 6
    total escaped pipes (a real table has header + separator + body)."""

def _unescape_markdownv2_tables(content: str) -> str:
    """Rewind \\| back to | inside rows that match pipe-table shape,
    leaving prose, code fences, and arithmetic untouched."""

Gate in _deliver_to_platform:

is_cron_path = bool((metadata or {}).get("job_id"))
if (
    target.platform == Platform.TELEGRAM
    and is_cron_path
    and _looks_like_cron_markdownv2_table(content)
):
    content = _unescape_markdownv2_tables(content)

The gate sits between the silence-narration filter and the send_metadata build-up. Logging at DEBUG level records size delta and chat_id when a rewind fires.

---

Scope — Why It Doesn't Collide with Open Rich PRs

Three open PRs add sendRichMessage fast-paths to tools/send_message_tool.py (#46118, #46952, #47190). This PR is intentionally non-overlapping:

• Touches gateway/delivery.py only — no _send_telegram edit
• Scope: cron-only (metadata.job_id), Telegram-only
• tools/send_message_tool.py is untouched

Both paths can coexist: cron-routed send_message goes via DeliveryRouter._deliver_to_platform and benefits from this rewind even if/when the _send_telegram rich PR lands.

---

Files Changed

File	Change
gateway/delivery.py	+130 (helpers + gate)
tests/gateway/test_delivery_cron_table_unescape.py	+206 (new, 15 tests)

---

Tests

15 new cases in tests/gateway/test_delivery_cron_table_unescape.py, all passing:

Class	Coverage
TestUnescapeMarkdownv2Tables	canonical reporter case, prose untouched, short escaped strings untouched, arithmetic untouched (≥6-pipe cut-off), empty/None, idempotency
TestLooksLikeCronMarkdownv2Table	real cron table detected, plain text not detected, arithmetic not detected, short 2-row tables not detected, empty/None, separator-only not detected
TestCronGateContract	cron + Telegram + table is rewound; same payload without job_id is left alone; cron + non-Telegram is left alone

---

Checklist

• Tests pass — 15/15 new
• Follows Conventional Commits
• Changes scoped to this fix only — 2 files
• Non-overlapping with open rich-send PRs (fix(send_message_tool): add sendRichMessage fast-path for Telegram #46118, fix: use rich Telegram messages for standalone sends #46952, fix: use Telegram rich messages in send_message tool #47190)

---

Risk & Impact

Low. Gate is triple-gated (platform == TELEGRAM AND job_id present AND table shape detected). Prose, code fences, arithmetic, and non-cron deliveries are all left untouched. Idempotency confirmed by test.

Type: 🐛 Bug fix
Closes: #53632

[teknium1]

Thanks for isolating the cron/Telegram symptom. The current formatter still misses pre-escaped table separators: gateway/platforms/helpers.py:287-292 requires literal pipes, while plugins/platforms/telegram/adapter.py:6537-6539 runs that converter before its generic MarkdownV2 escape at :6636-6637. The cron path reaches DeliveryRouter._deliver_to_platform() with job_id metadata (cron/scheduler.py:1675, :1694-1711), so the core premise remains valid.

Problems

• gateway/delivery.py:106-141 intentionally does not isolate code fences, yet it rewrites every matching row. A fenced, table-shaped escaped payload is therefore changed despite the stated code-block safety claim.
• tests/gateway/test_delivery_cron_table_unescape.py:155-165 mirrors the production predicate locally rather than exercising DeliveryRouter and the Telegram formatter; it would still pass if the real gate drifted or disappeared.
• The submitted diff at 07f1470e23312122684d1ad74739e5aa20c0bf96 also carries unrelated gateway cleanup, Docker CI, artifact, and process-test changes. The linked #54302 discussion likewise identifies the need for branch isolation.

Suggested changes

• Salvage the delivery fix alone, protect fenced regions, and add an end-to-end router-to-adapter regression for rich and legacy formatting.

Automated hermes-sweeper review.

[teknium1]

This explicitly skips fence isolation, but the subsequent row-level replacement mutates matching \| content inside a fenced code block. Please preserve fenced regions and add a negative regression; the adapter does not extract fences until after this DeliveryRouter transform.

[teknium1]

This mirrors the production conditional rather than invoking DeliveryRouter._deliver_to_platform, so it cannot catch removal or drift of the actual gate or verify the adapter receives the corrected content. Please replace it with an async router integration test using a recording Telegram adapter.