> ## Documentation Index > Fetch the complete documentation index at: https://docs.closient.com/llms.txt > Use this file to discover all available pages before exploring further. # Which Application Identifiers belong on the pack, per scan context > Anything that must produce a decision without a network connection goes on the pack. Everything else is a pointer. Each row classifies one AI for one scan context (consumer scan, retail POS, supply chain AIDC) as `on_pack_required`, `on_pack_recommended` or `server_side_eligible`, with a rationale. Supply chain AIDC is its own context because a receiving dock running a recall check on a pallet with no signal needs the lot on the pack, where a consumer scan does not. Placement is advisory: the URI grammar decides where an AI sits and which qualifiers are mandatory, and following a recommendation never yields a non-conformant URI. AIs the standard forbids in a Digital Link are omitted. **Keyless** — no API key, no signup. IP-throttled at 300 requests/minute and cached at the edge for 24h, so repeat calls for the same input do not reach origin. Over-rate callers get a `429` with a `Retry-After` header and a `retry_after` field — it never silently degrades or returns a wrong answer under load. ## OpenAPI ````yaml /openapi/openapi-resolver.json get /resolver/api/v1/public/gs1/placement openapi: 3.1.0 info: title: Resolver API version: 1.0.0 description: > GS1 Digital Link resolution with content negotiation and linkset support. ## Authentication All endpoints require an API key passed via the `X-API-Key` HTTP header, unless otherwise noted. ``` X-API-Key: csb__ ``` Generate API keys in **Settings > API Keys** in your dashboard, or via the Account API. Session-based (cookie) authentication is also accepted for browser-based access. ## Rate Limits | Tier | Requests / minute | Requests / day | |-------------|-------------------|----------------| | Default | 300 | 10,000 | | Custom | Contact us | Contact us | Rate-limit headers are included on every response so callers can self-throttle without hitting our 429s ("informed governor"): - `RateLimit-Policy` — every active window, e.g. `300;w=60, 10000;w=86400` - `RateLimit-Limit` — quota for the **most-restrictive** currently-active window - `RateLimit-Remaining` — requests left in that window - `RateLimit-Reset` — seconds until that window resets (relative; clock-skew safe) Legacy `X-RateLimit-*` aliases are also emitted for back-compat. `X-RateLimit-Reset` keeps the absolute Unix-timestamp shape to avoid breaking existing consumers. When rate-limited, you receive `429 Too Many Requests` with a `retry_after_seconds` field in the error envelope and a `Retry-After` header. ## Pagination List endpoints return paginated results in this envelope: ```json { "data": [...], "pagination": { "page": 1, "page_size": 25, "total_count": 342, "total_pages": 14, "has_next": true, "has_previous": false } } ``` Use `?page=2&page_size=50` query parameters. Maximum page size is 100. ## Error Responses All errors conform to [RFC 9457 Problem Details](https://www.rfc-editor.org/rfc/rfc9457) with `Content-Type: application/problem+json`: ```json { "type": "https://closient.com/docs/errors/not_found", "title": "Not Found", "status": 404, "detail": "The requested resource was not found.", "error_code": "not_found", "retryable": false, "timestamp": "2026-03-31T12:00:00+00:00" } ``` Common error codes: `unauthorized` (401), `forbidden` (403), `not_found` (404), `validation_error` (422), `rate_limited` (429), `internal_error` (500). termsOfService: https://www.closient.com/terms/ servers: - url: https://www.closient.com security: [] tags: - name: Resolver description: GS1 Digital Link resolution with content negotiation and linkset support. - name: Custom URLs description: >- Reusable custom-URL catalog (C-3339) — create, list, edit, and delete the custom redirect destinations that resolution rules point at. - name: Verification description: >- Serial verification (`gs1:verificationService`) — tiered, rate-limited responses for serialized GTIN scans. Experimental v1; see the verification-service guide. - name: GS1 Primitives (Public) description: >- Keyless GS1 Digital Link primitives (C-4295) — parse, validate, build, decompress, and check-digit analysis. **No API key, no signup.** Pure functions over strings: no database, no network, no catalog data. IP-throttled and edge-cached so repeat calls cost nothing. This is the reference implementation the resolver itself runs on. - name: Resolver Custom Hostnames description: >- BYO domain (C-4058) — register a customer-owned hostname, publish the CNAME records, verify ownership, and serve an org's Digital Link QRs from its own DNS. externalDocs: description: Closient Documentation url: https://docs.closient.com paths: /resolver/api/v1/public/gs1/placement: get: tags: - GS1 Primitives (Public) summary: Which Application Identifiers belong on the pack, per scan context description: >- Anything that must produce a decision without a network connection goes on the pack. Everything else is a pointer. Each row classifies one AI for one scan context (consumer scan, retail POS, supply chain AIDC) as `on_pack_required`, `on_pack_recommended` or `server_side_eligible`, with a rationale. Supply chain AIDC is its own context because a receiving dock running a recall check on a pallet with no signal needs the lot on the pack, where a consumer scan does not. Placement is advisory: the URI grammar decides where an AI sits and which qualifiers are mandatory, and following a recommendation never yields a non-conformant URI. AIs the standard forbids in a Digital Link are omitted. **Keyless** — no API key, no signup. IP-throttled at 300 requests/minute and cached at the edge for 24h, so repeat calls for the same input do not reach origin. Over-rate callers get a `429` with a `Retry-After` header and a `retry_after` field — it never silently degrades or returns a wrong answer under load. operationId: apps_resolver_api_public_gs1_ai_placement_public parameters: - in: query name: ai schema: description: Only this Application Identifier, e.g. `10`. title: Ai maxLength: 8 type: string pattern: ^[^\x00]{0,8}$ required: false description: Only this Application Identifier, e.g. `10`. - in: query name: context schema: description: Only this scan context. allOf: - $ref: '#/components/schemas/AIScanContextEnum' required: false description: Only this scan context. responses: '200': description: OK content: application/json: schema: $ref: '#/components/schemas/AIPlacementOut' '400': description: Bad Request content: application/problem+json: schema: $ref: '#/components/schemas/ErrorOut' '404': description: Not Found content: application/problem+json: schema: $ref: '#/components/schemas/ErrorOut' '405': description: Method Not Allowed content: application/problem+json: schema: $ref: '#/components/schemas/ErrorOut' '422': description: Unprocessable Content content: application/problem+json: schema: $ref: '#/components/schemas/ErrorOut' '429': description: Too Many Requests content: application/problem+json: schema: $ref: '#/components/schemas/ErrorOut' components: schemas: AIScanContextEnum: description: Who is scanning, and so what they can rely on being online. enum: - consumer_scan - retail_pos - supply_chain_aidc title: AIScanContextEnum type: string AIPlacementOut: examples: - principle: >- Anything that must produce a decision without a network connection goes on the pack. Everything else is a pointer. rows: - ai: '01' context: retail_pos grammar_forced: true grammar_position: path_key placement: on_pack_required rationale: >- The GTIN is the primary key of the Digital Link; the grammar requires it. properties: principle: description: The rule every row derives from. title: Principle type: string rows: description: >- One row per AI per scan context, after the `ai` and `context` filters. items: $ref: '#/components/schemas/AIPlacementRowOut' title: Rows type: array required: - principle - rows title: AIPlacementOut type: object ErrorOut: description: |- RFC 9457 Problem Details response. All API errors are returned in this format with Content-Type: application/problem+json. examples: - detail: The requested resource was not found. error_code: not_found retryable: false status: 404 timestamp: '2026-03-31T12:00:00+00:00' title: Not Found type: https://closient.com/docs/errors/not_found - detail: Validation error. details: - loc: - body - name msg: Field required type: missing error_code: validation_error retryable: false status: 422 timestamp: '2026-03-31T12:00:00+00:00' title: Validation Error type: https://closient.com/docs/errors/validation_error - detail: Rate limit exceeded. Please try again later. error_code: rate_limited retry_after: 31 retryable: true status: 429 timestamp: '2026-03-31T12:00:00+00:00' title: Rate Limited type: https://closient.com/docs/errors/rate_limited properties: type: description: URI reference identifying the error type. title: Type type: string title: description: Short human-readable summary of the error. title: Title type: string status: description: HTTP status code. title: Status type: integer detail: description: Human-readable explanation of this specific occurrence. title: Detail type: string error_code: description: Machine-readable error code (e.g. not_found, unauthorized). title: Error Code type: string retryable: default: false description: Whether retrying the same request can succeed. title: Retryable type: boolean timestamp: description: ISO 8601 timestamp of when the error occurred. title: Timestamp type: string retry_after: anyOf: - type: integer - type: 'null' description: Seconds to wait before retrying (when applicable). title: Retry After owner_action_required: anyOf: - type: boolean - type: 'null' description: Whether the error requires account owner intervention. title: Owner Action Required details: description: Additional context (validation errors, etc.). title: Details required: - type - title - status - detail - error_code - timestamp title: ErrorOut type: object AIPlacementRowOut: description: One AI's placement recommendation in one scan context. examples: - ai: '17' context: consumer_scan grammar_forced: false grammar_position: query_attribute placement: server_side_eligible rationale: >- Expiry can be looked up when the scanner is online; a consumer scan has a network. properties: ai: description: The Application Identifier, e.g. `17`. title: Ai type: string context: $ref: '#/components/schemas/AIScanContextEnum' description: The scan context this row applies to. placement: $ref: '#/components/schemas/AIPlacementEnum' description: Where to put this AI for this context. rationale: description: Why. Every row carries one; none is an unexplained opinion. title: Rationale type: string grammar_position: $ref: '#/components/schemas/AIGrammarPositionEnum' description: >- Where the URI grammar places the AI if it is encoded. Fixed by the standard, not by placement: data attributes are only ever in the query string (URI Syntax 1.7.0 section 4.10). grammar_forced: description: >- True when the grammar makes this AI mandatory, so it is on-pack whatever else applies. title: Grammar Forced type: boolean required: - ai - context - placement - rationale - grammar_position - grammar_forced title: AIPlacementRowOut type: object AIPlacementEnum: description: |- Where an Application Identifier belongs for a scan context (C-4782). Advisory only: the URI grammar decides where an AI sits and which are mandatory, and a recommendation never produces a non-conformant URI. enum: - on_pack_required - on_pack_recommended - server_side_eligible title: AIPlacementEnum type: string AIGrammarPositionEnum: description: Where the URI grammar puts the AI, whatever its placement. enum: - path_key - path_qualifier - query_attribute title: AIGrammarPositionEnum type: string ````