[ishwar00]

Agents can subscribe to responses about sent WhatsApp messages, including ordinary unquoted group replies. The service classifies incoming batches against the original request and sends pointer-only Postbag notices to the waiting agent. Unrelated group chatter stays quiet.

Flow: approve and send → subscribe using accepted draft IDs or outgoing message IDs → read relevant replies when notified → receive a fixed-deadline outcome. Already-stored replies are included, so fast responses arriving before subscription creation are recovered. Expired-anchor registrations are rejected. Catch-up starts at the first in-window revision, with no quiet delay on irrelevant history pages. There is no prepared-watch state or acknowledgment call.

• watch_replies, get_replies, and cancel_watch, with durable revisions and repeatable cursor reads.
• Decisions, cursor advancement and notice creation commit atomically. Model execution happens outside transactions.
• Context-sized batches isolate oversized messages without preventing neighboring replies from being classified. Chronological context includes interleaved owner/filtered messages. Uncertain results surface immediately as possible, without a recheck queue. Exact quoted replies remain relevant at expiry; tombstones do not trigger pushes.
• Notification credentials are stored once per agent/destination; renewal through one watch repairs sibling watches too.
• Four delivery states and bounded retries, including uncertain outcomes, with stable notice IDs/revisions. Duplicate pointers are safe; submission does not prove agent processing.
• Temporary configurable Claude Code/Codex classifiers, bounded context, fixed deadlines and call budgets. Existing human send approval remains client-enforced.

Setup: docs/replies.md. Push requires the Postbag extension in parasxos/postbag#31; a pinned fork install is documented. Pull does not require Postbag.

Validation:

• Typecheck/build clean; 95/95 bridge tests pass.
• Regression tests reproduce rollback at notice insertion, oversized-message isolation and batch pagination, shared-token renewal and concurrent rotations, default-delay catch-up over 1000 old messages, interleaved context, quoted deadline handling, immediate replies before subscription, fixed deadlines, unknown-submission retries, and concurrent registration idempotency.
• Real Haiku synthetic runs classified the valid DNS reply while isolating an oversized paste and unrelated chatter, including interleaved owner follow-ups and 1000 old messages; reply and expiry notices were submitted through Postbag. No WhatsApp messages sent.
• The unchanged Postbag dependency previously passed its full 686-test suite; its six focused service tests pass again.
• Claude simplify-by-design review requested for the final committed implementation; no blockers at source commit 0cf8be7. Its synthetic busy-group probe confirms catch-up improved from 66 to 6 simulated seconds with default batching delay.

Limits: classification can misjudge relevance; audit reads retain unrelated/unclassified candidates. CLI isolation depends on installed flags and is not an OS security boundary. Only messages delivered by WhatsApp are available.