{"id":"forward-only-is-universal-processing-primitive","text":"Forward-only correctness is the codebase's universal processing primitive, applying uniformly across all three processing paradigms: event streams (exactly-once via coordinated dedup and finalization), task orchestration (DAG forward progress via control-data separation), and message delivery (bounded retry with escalation to permanent failure).","truth_value":"IN","source":"","source_url":"","source_hash":"","justifications":[{"type":"SL","antecedents":["event-and-task-processing-share-forward-only-correctness","notification-instantiates-forward-only-delivery"],"outlist":[],"label":"depth-5 beliefs covering streams+tasks and delivery are both unused; combining reveals forward-only spans every processing paradigm, not just data and execution layers"}],"dependents":["forward-only-is-the-architectures-load-bearing-constraint","forward-only-unifies-processing-and-conflict-resolution"],"metadata":{},"created_at":"","updated_at":"","reviewed_at":"","verified_at":"","retracted_at":"","explanation":{"steps":[{"node":"forward-only-is-universal-processing-primitive","truth_value":"IN","reason":"SL justification valid","antecedents":["event-and-task-processing-share-forward-only-correctness","notification-instantiates-forward-only-delivery"],"label":"depth-5 beliefs covering streams+tasks and delivery are both unused; combining reveals forward-only spans every processing paradigm, not just data and execution layers"},{"node":"event-and-task-processing-share-forward-only-correctness","truth_value":"IN","reason":"SL justification valid","antecedents":["forward-only-stream-processing-is-exactly-once","control-data-separation-enables-forward-progress"],"label":"two independent processing domains converge on the same no-regression mechanism"},{"node":"forward-only-stream-processing-is-exactly-once","truth_value":"IN","reason":"SL justification valid","antecedents":["dedup-and-finalization-are-coordinated","forward-only-design-prevents-regression-and-maximizes-progress"],"label":"Global dedup keying (event_id alone, not per ad_id) means two legitimate events sharing an ID across different entities are silently merged, breaking per-entity exactly-once semantics","outlist":["dedup-is-global-not-per-ad"]},{"node":"dedup-and-finalization-are-coordinated","truth_value":"IN","reason":"SL justification valid","antecedents":["dedup-outlives-aggregation-window","watermark-finalization-is-irreversible"],"label":"Irreversible finalization demands that dedup outlive the window — these two depth-1 conclusions are not independent but structurally dependent"},{"node":"dedup-outlives-aggregation-window","truth_value":"IN","reason":"SL justification valid","antecedents":["dedup-pruning-uses-2x-lateness","watermark-drives-finalization"],"label":"The 2× multiplier ensures dedup coverage extends beyond the point where corrections would be impossible"},{"node":"dedup-pruning-uses-2x-lateness","truth_value":"IN","reason":"premise"},{"node":"watermark-drives-finalization","truth_value":"IN","reason":"premise"},{"node":"watermark-finalization-is-irreversible","truth_value":"IN","reason":"SL justification valid","antecedents":["watermark-drives-finalization","window-lifecycle-one-directional","no-window-merging-or-retraction"],"label":"Three properties compose into hard irreversibility: watermark-only trigger + one-way lifecycle + no retraction"},{"node":"window-lifecycle-one-directional","truth_value":"IN","reason":"premise"},{"node":"no-window-merging-or-retraction","truth_value":"IN","reason":"premise"},{"node":"forward-only-design-prevents-regression-and-maximizes-progress","truth_value":"IN","reason":"SL justification valid","antecedents":["state-ratchets-prevent-regression-across-domains","pipeline-processing-maximizes-forward-progress"],"label":"State ratchets and forward-progress pipelines are complementary mechanisms — ratchets prevent regression in stateful systems, pipelines prevent regression in dataflow systems"},{"node":"state-ratchets-prevent-regression-across-domains","truth_value":"IN","reason":"SL justification valid","antecedents":["chat-monotonic-read-progress","watermark-finalization-is-irreversible"],"label":"chat read cursors are monotonic (never re-mark as unread), aggregation windows follow OPEN→CLOSED→FINALIZED with no reversal — both are state ratchets that make backwards movement structurally impossible"},{"node":"chat-monotonic-read-progress","truth_value":"IN","reason":"SL justification valid","antecedents":["chat-dual-ordering-sequence-and-lamport","chat-read-cursors-monotonic"],"label":"Sequence-number ordering + monotonic cursors create an irreversible read-progress guarantee"},{"node":"chat-dual-ordering-sequence-and-lamport","truth_value":"IN","reason":"premise"},{"node":"chat-read-cursors-monotonic","truth_value":"IN","reason":"premise"},{"node":"pipeline-processing-maximizes-forward-progress","truth_value":"IN","reason":"SL justification valid","antecedents":["video-pipeline-maximizes-useful-work-on-failure","watermark-finalization-is-irreversible"],"label":"Video pipeline (branch-independent failure containment) and stream processing (irreversible finalization) both embody the same forward-only processing principle"},{"node":"video-pipeline-maximizes-useful-work-on-failure","truth_value":"IN","reason":"SL justification valid","antecedents":["dag-failure-cascade","youtube-pipeline-dag-structure"],"label":"DAG topology + selective cascade means a thumbnail failure doesn't block a successful transcode"},{"node":"dag-failure-cascade","truth_value":"IN","reason":"premise"},{"node":"youtube-pipeline-dag-structure","truth_value":"IN","reason":"premise"},{"node":"control-data-separation-enables-forward-progress","truth_value":"IN","reason":"SL justification valid","antecedents":["video-pipeline-separates-control-from-data-flow","forward-only-design-prevents-regression-and-maximizes-progress"],"label":"decoupling control (DAG) from data (ctx dict) is what makes forward-only failure handling safe in practice"},{"node":"video-pipeline-separates-control-from-data-flow","truth_value":"IN","reason":"SL justification valid","antecedents":["youtube-ctx-dict-blackboard","youtube-pipeline-dag-structure"],"label":"DAG handles ordering and failure; ctx dict handles data — neither constrains the other"},{"node":"youtube-ctx-dict-blackboard","truth_value":"IN","reason":"premise"},{"node":"notification-instantiates-forward-only-delivery","truth_value":"IN","reason":"SL justification valid","antecedents":["notification-delivery-is-bounded","forward-only-extends-to-failure-handling"],"label":"Notification's bounded retry lifecycle is structurally isomorphic to forward-only failure handling"},{"node":"notification-delivery-is-bounded","truth_value":"IN","reason":"SL justification valid","antecedents":["notification-defensive-double-rate-check","retry-escalates-to-permanent-failure"],"label":"complementary boundedness — rate checks bound throughput, retry escalation bounds duration"},{"node":"notification-defensive-double-rate-check","truth_value":"IN","reason":"SL justification valid","antecedents":["notif-two-phase-rate-limit","notif-rate-limit-on-success-only"],"label":"Queue delay between the two check points means neither alone is sufficient; failed retries not consuming budget prevents limit exhaustion from transient failures"},{"node":"notif-two-phase-rate-limit","truth_value":"IN","reason":"premise"},{"node":"notif-rate-limit-on-success-only","truth_value":"IN","reason":"premise"},{"node":"retry-escalates-to-permanent-failure","truth_value":"IN","reason":"SL justification valid","antecedents":["notif-exponential-backoff-with-jitter","retry-converts-timeout-to-failure"],"label":"Backoff prevents cascading load; finite retry count ensures eventual resolution (success or permanent failure) rather than indefinite limbo"},{"node":"notif-exponential-backoff-with-jitter","truth_value":"IN","reason":"premise"},{"node":"retry-converts-timeout-to-failure","truth_value":"IN","reason":"premise"},{"node":"forward-only-extends-to-failure-handling","truth_value":"IN","reason":"SL justification valid","antecedents":["forward-only-design-prevents-regression-and-maximizes-progress","retry-escalates-to-permanent-failure"],"label":"The d3 forward-only node covers normal state progression; the d1 retry node covers failure progression — the emergent property is that both follow the same no-rollback principle"}]}}