TimeBack Platform Content Alpha Architecture

render

Return the exact blank thing a student can use without exposing answers, attempts, or QTI internals.

discover

Find and compare reusable Content through governed fields, relationships, and catalog sidecars without inference.

interoperate

Import, export, reference, and reconcile Content without a parallel store or translation-only business rules.

Content asset identity

Content is one row per asset. A Content row references other Content rows through content_ref/content_reference rows and never nests another Content row or stores collection membership.

• one video row
• one transcript media_asset row
• content_reference relationship_kind=transcript_for
• course/unit/playlist membership lives in Curriculum

Alpha read resources

SQL views over the approved qti.* and platform.* base tables. Rename, cut, and restrict add no storage.

• alpha.content_item_view
• alpha.content_version_view
• alpha.media_asset_view
• alpha.answer_slot_view
• alpha.assessment_component_view
• alpha.scoring_plan_view

Alpha extension storage

Tables that contain only new Alpha columns plus foreign keys to base rows. No extension table may copy a 1EdTech-sourced field.

• alpha.content_item_extension.expected_xp
• alpha.assessment_test_extension
• alpha.media_asset_extension
• alpha.content_reference
• alpha.content_kc_tag
• alpha.content_curriculum_link (frozen archive)
• alpha.content_catalog_facet
• alpha.content_catalog_facet_assignment
• alpha.content_trust_evidence
• alpha.content_test_serve_grant
• alpha.content_test_serve_authorization

Results-owned read dependencies

Content may read Results-owned public views, but Content never creates, migrates, writes, or backfills those objects.

• alpha.content_effectiveness public Results view with tenant_id, object_id, and data JSONB

Core writes

Writes that create or change QTI-backed core objects are write-through commands to the QTI 1EdTech base surface. Alpha does not own a parallel writable content catalog.

• QTI package import
• QTI artifact/version authoring save
• manifest-resource/webcontent creation

Forbidden downstream output

Any CREATE TABLE alpha.content_item, alpha.content_version, alpha.answer_slot, alpha.answer_key, alpha.assessment_component, alpha.scoring_plan, alpha.video, alpha.audio, alpha.image, or alpha.media_asset that stores qti.* columns is a rollback failure.

• Duplicated title/language/latest_version_id
• Copied delivery_json/authoring_json
• Copied correct_response/processing_rule

Tag registry vs. real column

Number: 1

ContentObligation: Content uses weighted content_kc_tag relationship rows for registry-KC alignment and typed content_reference rows for content-to-content relationships; content_curriculum_link remains a frozen archive. Typed view/extension columns hold content_kind, expected_xp, subject_id, target_grade_id, media_type, test_type, is_mastery_gate, test_family_id, usage_scope, source_system, and source_record_id. Catalog discovery dimensions live in named governed sidecars and promote to real columns only when they become join, constraint, or computed inputs.

Point-in-time default

Number: 2

ContentObligation: Content is not roster membership. Authoring and TimeBack ingest use immutable base QTI rows or extension rows keyed to exact versions, and list reads preserve version identity. Content must not expose a 'current only' shortcut that hides which version a student saw; changed source bytes append, and historical hash replay never rolls the served pointer backward.

Typed field, never parsed

Number: 3

ContentObligation: Content kind, expected_xp, curated expected_xp_band assignments, subject, grade band, modality, language, test type, mastery gate, usage scope, media kind, media type, source family, source record id, and source activity ref are set on base write-through, source ingest, extension write, or catalog curation and never inferred from titles, URLs, package paths, MIME type, or display text at read time. The documented expected_xp_band= convenience filter is a runtime-owned numeric projection over expected_xp, not evidence of a stored facet assignment.

Policy config

Number: 4

ContentObligation: Content thresholds and policy lists, including effectiveness freshness, display cutoffs, catalog facet value sets, speed-running calibration rules, and expected_xp banding, live under alpha.policy.* and are not duplicated in apps.

Event/result/gradebook separation

Number: 5

ContentObligation: Content holds blank instruments and media. Events holds interactions. Results holds answers, scores, mastery, and gradebook rollups.

Two graphs, two homes

Number: 6

ContentObligation: Content links to Curriculum's shared graph. It never stores the student's knowledge graph or mastery state.

NWEA account boundary

Number: 7

ContentObligation: Content does not carry brand/modality/NWEA account grouping. MAP-related content can carry subject/test family, while district account grouping remains People & Orgs/Results.

Secrets are not fields/tags

Number: 8

ContentObligation: Content metadata, media records, and tags cannot contain student app credentials, raw tokens, or secret values.

XP ledger separation

Number: 9

ContentObligation: expected_xp is student-independent Content configuration. Speed-running is the accepted calibration policy, but current publication/import paths do not require proof of a speed-run and may persist policy-derived or default values. Awarded XP, repeat-attempt discounts, effort signals, negative XP, and reward triggers live in the Results XP ledger and Policy, never in Content.

Content effectiveness rollup

Number: 10

ContentObligation: Results owns alpha.content_effectiveness as the derived rollup over settled result evidence. Content exposes a read endpoint that queries the Results-owned public view and safely returns insufficient_data when no Results evidence exists; apps never maintain counters.

Named ingest adapters

Number: 11

ContentObligation: Content owns the TimeBack production content ingest adapter for source-shaped content/activity-reference rows and stores nullable blank test_family_id. Current import does not populate/resolve that family id, Results has no Content family foreign key, and the importer neither appends frozen curriculum-link rows nor mints content_kc_tag rows without an authorized registry resolution workflow. Implemented import failures return HTTP 400 or 422 Problems, never HTTP 200 Problems.

Universal gate failure protocol

Number: 12

ContentObligation: Content owns the blank spec/bank/forms as the entity home (#72, content-itd-020): a mastery_gate gating member target_ref points at a Content test_bank (curriculum/alpha caitd-013), and 'equivalent form' resolves to the lowest-index unseen bank member whose content_reference.usage_scope and referenced content_item.usage_scope are both practice_eligible; held_out_canary and secure_form remain readable but excluded from routine retries/practice. Gate fields, passing_criteria, on_fail, retake cooldown, and the mastery-cutoff number stay on Curriculum course_component_member and alpha.policy; the spec's passing_rule is referenced, never restated as a number. A grade gate's bank must hold at least the spec's min_forms equivalent forms. Content tests remain reusable blank instruments that may be gated differently in different members.

Rewards and motivation are Policy

Number: 13

ContentObligation: 100for100 payouts, league promotions, streak bonuses, penalties, and reward amounts never live on Content rows or catalog facets.

Goal-to-effort conversion

Number: 14

ContentObligation: GOALS reads expected_xp through Content/Curriculum and Results/Policy. Content does not predict hours, calendar dates, RIT targets, or course progress.

LOR clone storage

Number: 15

ContentObligation: Merlot, OER Commons, Khan Academy library, IXL skill plans, question banks, playlists, and libraries add no clone-specific Content storage; they are recipes over one-row-per-asset Content, content_ref/content_reference rows, Curriculum, catalog facets, and Common Cartridge transport.

Locked vocabulary

Number: 16

ContentObligation: Content items are views or configuration. expected_xp is config. content_effectiveness is a Results-owned derived read. Awarded XP is a Results ledger entry. Course progress is a measure outside Content. Future GOALS output is a prediction outside Content.

Receipt-backed exact-version release eligibility

Number: 17

ContentObligation: Content computes release_eligible exactly equal to serveable from the owning item lifecycle, item revocation state, and the server-owned QC receipt for the requested immutable version: status=published, retired_at=null, item trust trusted/degraded, and the matching version receipt trusted/degraded. A later version cannot inherit an older receipt. Setting item trust_status=failed is the immediate all-version revocation lever. No producer release evidence, required quality-bar tuple, owner allowlist, or second attestation participates. Curriculum stores only its exact Content reference and asks Content at authoring and launch; consumers never copy or recompute serveable or release_eligible.

Bounded test-bank graph writes

Number: 18

ContentObligation: Every active test-bank graph writer budgets its complete post-write result inside the owning transaction under the tenant graph fence: public and repository/direct active embeds and bank_member writes, KC-tag upsert/revival, QTI package import, and TimeBack materialization. A cardinality-neutral active repository/materializer replay still executes this budget; a completed API idempotency replay returns its prior result without executing a graph writer. One write may affect at most 1,024 banks, and every affected bank may have at most 1,024 active bank-member facts and 4,096 joined form/question/active-KC facts. All three ceilings are inclusive. The 1,025th affected bank or active member and the 4,097th joined fact return HTTP 409 content.invalid_test_bank_member_contract; member overflow identifies fieldErrors.name=bank_members, while affected-bank and joined-fact overflow identify fieldErrors.name=form_graph. The rejected transaction leaves no lasting graph, parent timestamp/ETag, or fresh idempotency-ledger effect. Retirement remains available as remediation: retire active member/embed/KC-tag facts or split shared forms/questions/banks to reduce fanout, then retry.

Content owns the stored HTML body vocabulary; Curriculum selects renderer_ref per member; QTI owns XML/scoring; Events/Results own durable learner progress. The renderer and host must not create a private progress store.

Name: tb_markup_renderer_progress_seam

Owner: Content dictionary with Curriculum renderer_ref and Events/Results progress seams

Tokens: tb-instructional-content; tb-article-container; tb-segment; tb-interaction; tb-qti-assessment-item; tb-applet; tb-catalog; tb-qti-config; tb-applet-config; data-catalog-idref; practice-step; example-practice-container; headers-row; header; step-row; step; example-step; answer-box; tb-glossary-term; tb-glossary-definition; tb-narration; tb-narration-audio

Renderer: {"renderer_ref":"renderer:interactive-lesson","iframe_url":"https://platform3-andymontgomery-9773s-projects.vercel.app/player","playground_url":"https://platform3-andymontgomery-9773s-projects.vercel.app/player?demo=1","implementation_ref":"platform3:first-party-reference-player:/site/player","versioned_iframe_url":"https://platform3-andymontgomery-9773s-projects.vercel.app/player/versions/2026-08-05.issue-2501-article-html/","player_version":"2026-08-05.issue-2501-article-html","capability_matrix_url":"https://platform3-andymontgomery-9773s-projects.vercel.app/player/renderer-capabilities.json","registered_for_routing":true,"verified_rendering":true,"rendering_state":"verified_partial","content_load_fields":["html","qtiXml","testForm","title","contentId","contentRef","gateComponentId","studentId","interactiveComposition","contentState","config"],"host_messages":["CONTENT_LOAD","TTS_GENERATE_RESPONSE"],"renderer_messages":["CONTENT_READY","CONTENT_STATE_CHANGE","CONTENT_RESIZE","CONTENT_ERROR","TTS_GENERATE_REQUEST"],"preview_affordances":["ad_hoc_html","ad_hoc_qti_xml_a1_text_structural","exact_test_form_fixture"]}