A controlled task chain from evidence to publication

Realization and trade-offs

code example

SQLite: local publish intent same transaction as outbox

Works on an empty SQLite database. The example only demonstrates local transaction writing and publishing intent, and does not implement permissions, approvals, consumers, peer idempotency, and recovery after version changes. You cannot claim end-to-end exactly-once based on this. Any statement failure must roll back the entire transaction by the caller; after the outbox insertion fails, the updated report status cannot be continued.

PRAGMA foreign_keys = ON;
CREATE TABLE report (
  tenant_id TEXT NOT NULL,
  report_id TEXT NOT NULL,
  version INTEGER NOT NULL,
  status TEXT NOT NULL CHECK (status IN ('draft', 'publishing', 'published')),
  PRIMARY KEY (tenant_id, report_id)
);
CREATE TABLE publish_outbox (
  tenant_id TEXT NOT NULL,
  action_id TEXT NOT NULL,
  report_id TEXT NOT NULL,
  report_version INTEGER NOT NULL,
  status TEXT NOT NULL DEFAULT 'pending',
  PRIMARY KEY (tenant_id, action_id),
  FOREIGN KEY (tenant_id, report_id) REFERENCES report(tenant_id, report_id)
);
INSERT INTO report VALUES ('tenant-a', 'report-1', 3, 'draft');
BEGIN TRANSACTION;
UPDATE report SET status = 'publishing'
WHERE tenant_id = 'tenant-a' AND report_id = 'report-1'
  AND version = 3 AND status = 'draft';
INSERT INTO publish_outbox (tenant_id, action_id, report_id, report_version)
SELECT 'tenant-a', 'action-1', report_id, version FROM report
WHERE tenant_id = 'tenant-a' AND report_id = 'report-1'
  AND changes() = 1;
COMMIT;
SELECT report_id, report_version, status FROM publish_outbox;

expected output

report-1|3|pending

Engineering deduction

scene

Hypothetical engineering scenario: The fund management department requires the report to cite both system documents and account flow, and release it after confirmation by the supervisor.

design decisions

The read interface enforces tenant permissions, the numbers are calculated by the determiner, and reports and release approvals are bound to versions.

Verify target

The goal is that each number can be played back, unapproved manuscripts cannot be published, and repeated messages do not generate additional business actions; it has not yet been verified as a real enterprise effect.

applicable boundary

The sample outbox only covers local transactions, and peer consistency relies on idempotent interfaces or result verification.

Easy to make mistakes

• Treat vector similarity filtering as permission isolation.
• It is thought that saving the checkpoint will automatically ensure that the external writing is done once.
• Treat external service timeouts as failures and retry unconditionally.

References

It is designed based on public technical information; the reference materials support the technical mechanism, and the scenarios and scoring standards are designed by this website and do not represent the original interview questions of a certain company. New Q&A and migration cases are added for principle explanation, and source verification and case operation verification are recorded separately.

• LangGraph: Persistence and Thread Checkpointing
• Temporal: Activity retry, receipt and cancellation
• MCP：Authorization
• PostgreSQL: Transaction Isolation and Consistent Snapshots
• AWS: Transaction outboxing and duplicate delivery

Check how far you understand

After reading, you can explain the principles, boundaries, and trade-offs against these standards. It is up to you to evaluate your mastery; if further verification is needed, complete the small tasks below.

Basic standards met

It can separate search, query, generation and approval for release.

Intermediate and advanced signals

Clarify data permissions, definitions, persistence and tool receipts.

Senior Signal

Capacity, cost, fault recovery, canary release and end-to-end acceptance are given.