{"data":{"@kind":"endpoint_example","endpoint_id":"universal-card","path":"/api/v1/universal/card/[sku]","method":"GET","auth":"public","title":"One card — math-mirror representation","description":"Returns a card in language-free encoding with cryptographic content_hash, ratios, ISO+epoch timestamps, typed graph edges.","curl":"curl https://cambridgetcg.com/api/v1/universal/card/op-op01-001-ja","sample_response":"{\n  \"@self_hash\": \"sha256:...\",\n  \"@encoding\": \"cambridge-tcg/universal/v1\",\n  \"@kind\": \"card\",\n  \"@content_hash\": \"sha256:abc123...\",\n  \"@retrieved_at\": { \"iso8601\": \"2026-05-14T12:00:00Z\", \"unix_epoch_seconds\": 1747224000 },\n  \"@sources\": [\"storefront-rds.card_price_history\"],\n  \"@source_license\": [\"CC0-1.0\"],\n  \"_note_opaque\": [\"name\", \"art_description\", \"rarity.natural_label\", \"variant.natural_label\"],\n  \"_links\": { \"self\": \"...\", \"parent\": \"...\", \"siblings\": \"...\", \"federation\": \"...\" },\n  \"rarity\": { \"natural_label\": \"leader\", \"ratio_in_pulls\": \"1/64\", \"decimal_probability\": 0.015625, ... },\n  \"price\": {\n    \"magnitude\": 5.40,\n    \"currency_token\": \"GBP\",\n    \"ratio_to_platform_median_card_price\": 0.95,\n    \"ratio_to_minimum_currency_unit\": 540,\n    \"magnitude_freshness\": { \"iso8601\": \"2026-05-14T03:14:22Z\", \"decimal_age_seconds\": 31538, ... }\n  },\n  \"in_set\": { \"edge_kind\": \"member_of_set\", \"target_natural_token\": \"OP01\", \"target_hash\": \"sha256:...\" },\n  \"of_game\": { \"edge_kind\": \"in_game\", \"target_natural_token\": \"op\", \"target_hash\": \"sha256:...\" },\n  \"name\": { \"natural_token\": \"Monkey D. Luffy\", \"resolved_lang\": \"en\", \"resolved_from\": \"name_en\", ... },\n  \"image_url\": \"https://...\"\n}","annotated_fields":[{"path":"@content_hash","meaning":"Stable identity across retrievals when card facts are unchanged. Compare to detect changes."},{"path":"@self_hash","meaning":"Hash of this particular rendering. Differs by density param even when content_hash matches."},{"path":"@sources","meaning":"Where the data came from. Parallel to @source_license."},{"path":"@source_license","meaning":"Per-source redistribution tier. CC0-1.0 / internal-only / partner-redistributable / proprietary."},{"path":"price.magnitude_freshness.decimal_age_seconds","meaning":"Seconds since the price was last known to be true."},{"path":"_note_opaque","meaning":"Natural-language fields the decoder cannot ground from structure."},{"path":"_links.federation","meaning":"URL to resolve this card's content_hash on another federated platform."}],"when_to_use":"Every per-card lookup. The workhorse endpoint.","gotchas":["Use ?density=sparse for low-bandwidth (drops _note_opaque + most edges).","Use ?density=saturated for one-hop neighbour resolution.","The content_hash includes captured_on — daily price updates produce daily hash changes even when nothing else moved.","Set Accept-Language header for non-English name resolution."],"see_also":[{"label":"Universal representation spec","href":"/methodology/universal-representation"},{"label":"Guide: track-one-card","href":"/api/v1/guides/track-one-card"},{"label":"Federation resolution","href":"/api/v1/examples/federation-identify"}]},"_meta":{"spec_version":"1","endpoint":"/api/v1/examples/[endpoint_id]","retrieved_at":"2026-05-13T18:56:04.907Z","as_of":"2026-05-13T18:56:04.907Z","sources":["ctcg-derived"],"freshness_seconds":86400,"license":"CC0-1.0","request_id":"req_b345dce1-f9f","deprecation":null,"next_link":null,"self_reference":{"this_endpoint":"/api/v1/examples/[endpoint_id]","contains_self":true},"source_license":["CC0-1.0"]}}