After token buckets (17 Nov), this post covers the inbox pattern: atomic consume with side effects, stable message keys, durable unique gates, retention TTL, reorder tolerance, failure ordering, pairing with outbox and duplicate-hit metrics.

अन्तःपेटिकाधर्मः: A Metrical Codification of the Inbox Pattern (with English glosses)

What this post is about

Inbox pattern persists consumer-side message ids with business effects so at-least-once delivery does not double-apply work.

Topics covered

1. Double delivery risk
2. Same TX as side effects
3. Stable producer message ids
4. Durable unique constraint
5. Inbox row TTL
6. Reorder-tolerant handlers
7. Mark only with success
8. Pair with outbox
9. Duplicate hit metrics
10. Outbox vs inbox vs idempotency keys

Sanskrit title

अन्तःपेटिकाधर्मः = antaḥ-peṭikā-dharmaḥ “dharma of the inner box” (inbox).

English

Minimizable; Sanskrit-first.

ग्राह्यम् / Keep

१. insert inbox id with effects: one local TX
२. use producer message ids: not fragile hashes only
३. unique constraint durable: multi-pod safe
४. TTL/archive inbox rows: bound growth
५. tolerate reorder: across partitions
६. never mark before success: alone
७. pair outbox+inbox: on money paths

त्याज्यम् / Avoid

• check memory set then act without TX
• inbox insert before business commit in separate steps
• unbounded inbox table forever

पदच्छेदः
बाह्यसन्देशः यदि द्विः पतति तदा द्विकर्म भयम् । अन्तःपेटिकाधर्मस्तस्माद् द्वारलेखः ॥१॥

Word-for-word

Gloss table

English sense
An inbox records processed message ids at the consumer so at-least-once delivery does not become at-least-twice business effects.

Context / topic
Topic: why inbox. Distinct from outbox which guards producer birth of messages.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
insert inbox id same TX as side effects । check then act race ॥२॥

Word-for-word

Gloss table

English sense
Store the message id in the same local transaction as the business writes. Separate check-then-act races duplicates.

Context / topic
Topic: atomic consume.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
natural key: producer id + message id । only payload hash fragile ॥३॥

Word-for-word

Gloss table

English sense
Prefer explicit idempotency keys from the producer. Payload hashes break on legitimate retries with extra fields.

Context / topic
Topic: keys.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
unique constraint is the gate । app memory set multi-pod miss ॥४॥

Word-for-word

Gloss table

English sense
Enforce inbox uniqueness in durable storage visible to all consumers not only a process-local set.

Context / topic
Topic: durable gate.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
TTL cleanup old inbox rows कोष । infinite grow मन्दः ॥५॥

Word-for-word

Gloss table

English sense
Expire or archive inbox rows after the duplicate window. Unbounded inboxes become a new ops patient.

Context / topic
Topic: retention.

वृत्तमिति: एकादशाक्षराः पादाः।

पदच्छेदः
handler must be inbox-aware reorder । assume total order always मा ॥६॥

Word-for-word

Gloss table

English sense
Duplicates and reordering still happen across partitions. Design handlers that tolerate both with inbox help.

Context / topic
Topic: ordering.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
poison: fail without inbox insert । insert then fail skip forever ॥७॥

Word-for-word

Gloss table

English sense
Only mark inbox after successful effects or in the same TX that commits them. Marking before success skips retries forever.

Context / topic
Topic: failure order.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
outbox + inbox ends-to-end । one side only residual dual ॥८॥

Word-for-word

Gloss table

English sense
Outbox makes birth atomic with producer state; inbox makes apply atomic with consumer state. Use both on money paths.

Context / topic
Topic: pair with outbox.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
metrics: duplicate hit rate inbox size । invisible filter अन्धता ॥९॥

Word-for-word

Gloss table

English sense
Count how often inbox rejects duplicates and how large the table grows.

Context / topic
Topic: observability.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
आउटबॉक्स जन्म रक्षति अन्तःपेटिका प्रभाव रक्षति । इदमर्थकुञ्चिका सामान्यम् ॥१०॥

Word-for-word

Gloss table

English sense
Outbox guards message birth; inbox guards side effects; idempotency keys are the shared language between them.

Context / topic
Topic: series distinctions.

सन्धिः: पटल जन्म; पेटिका प्रभाव; कुञ्चिका नाम।

वृत्तमिति: एकादशाक्षराः पादाः।

पदच्छेदः
atomic-key durable TTL order pair पञ्चकम् । एभिरन्तःपेटिकाधर्मो द्वारलेखसमन्वितः ॥११॥

Word-for-word

Gloss table

English sense
Five limbs: same-TX mark, stable ids, durable unique gate, bounded retention and pairing with outbox on critical flows.

Context / topic
Topic: checklist.

वृत्तमिति: ८-८-८-८।

पदच्छेदः
इत्यन्तःपेटिकाधर्मसारो द्वारलेखसमन्वितः । मितं द्विःपानं क्रियायोग्यं तन्त्रधर्मः स उच्यते ॥१२॥

Word-for-word

Gloss table

English sense
Closing: drink each message once in business truth even when the network delivers it twice.

Context / topic
Topic: close.

उपसंहारन्यायः: चिह्नं सह प्रतिज्ञा; द्वारं दृढं कुरु; जन्मना सह योजय।

वृत्तमिति: ८-८-८-८।

१. Why inbox
२. Atomic TX
३. Keys
४. Durable gate
५. TTL
६. Reorder
७. Fail order
८. Pair outbox
९. Metrics
१०. Series
११. Five limbs
१२. Close

1. Prior: outbox 2026-09-28; idempotency 2026-10-04; token bucket 2026-11-17.
2. Domain: inbox consumer pattern.
3. English minimizable; Sanskrit-first.
4. Style: no em dash; no Oxford comma in English clauses.