Changelog

All notable changes to Tink are documented here.

The format follows Keep a Changelog. Tink uses Semantic Versioning.

[Unreleased]

[0.1.1] - 2026-03-11

Three days of fixes, refactoring, cache integration, static analysis cleanup, and project scaffolding on top of the empty 0.1.0 skeleton.

March 9 — Initial SDK Implementation

All 35 source files written from scratch, implementing the full Tink API surface.

Core infrastructure

• Tink.Application — OTP application, Finch pool supervision, Cachex child spec
• Tink.Client — HTTP client struct, token attachment, cacheable-pattern detection
• Tink.Config — runtime config reader with typed accessors
• Tink.Auth / Tink.AuthToken — OAuth 2.0 client credentials and authorization code flows
• Tink.Error — unified error struct (status, code, message, request_id)
• Tink.HTTPBehaviour — behaviour contract for HTTP adapters
• Tink.HTTPAdapter — Finch-backed implementation with request/response encoding
• Tink.Retry — exponential backoff with jitter for 429 / 503 / network errors
• Tink.RateLimiter — per-key rate limiting via Hammer
• Tink.Cache — Cachex wrapper with TTL helpers and user-scoped invalidation
• Tink.Helpers — shared URL building and query encoding utilities
• Tink.Connector — provider connection utilities
• Tink.WebhookHandler — event dispatch and handler registration
• Tink.WebhookVerifier — HMAC signature verification

Domain modules

• Tink.Accounts, Tink.Users, Tink.Categories, Tink.Statistics
• Tink.Transactions, Tink.TransactionsOneTimeAccess, Tink.TransactionsContinuousAccess
• Tink.AccountCheck, Tink.BalanceCheck, Tink.BusinessAccountCheck
• Tink.IncomeCheck, Tink.ExpenseCheck
• Tink.RiskInsights, Tink.RiskCategorisation
• Tink.Investments, Tink.Loans
• Tink.Budgets, Tink.CashFlow, Tink.FinancialCalendar
• Tink.Providers, Tink.Connectivity, Tink.Link

March 10 — Bug Fixes, Security, and Structural Refactoring

Fixed — Critical Bugs

• link.ex — add_test_params/2: params variable was unbound, causing a compile error
• statistics.ex — Duplicate defmodule Tink.Statistics block (lines 367–end) caused a compile conflict; removed
• balance_check.ex — build_consent_update_link/2: URL was missing the https:// scheme, producing a malformed link
• connector.ex — String interpolation bug: literal "demo-scenario_str" was never interpolated; corrected to "demo-#{scenario_str}"
• client.ex — do_delete/3 had two contradictory success match clauses; unified to consistently return {:ok, body} or {:ok, %{}}, matching all other HTTP verb helpers

• users.ex — delete_credential/2 @spec declared return type as :ok; corrected to {:ok, map()} | {:error, Error.t()}

Fixed — Security

• webhook_verifier.ex — Replaced non-constant-time secure_compare/2 with :crypto.hash_equals/2 to eliminate a timing side-channel vulnerability in webhook signature verification

Fixed — Correctness

• config.ex — Rate limit config key mismatch: code read from nested :rate_limit but docs specified flat :enable_rate_limiting; aligned to flat key throughout
• webhook_handler.ex — validate_payload/1 was defined but never called; added to the with pipeline so invalid payloads are rejected before dispatch
• webhook_handler.ex — Test webhooks from the Tink console were being dispatched as :unknown events; added check_not_test_webhook/1 guard to intercept and acknowledge them without dispatch
• cache.ex — Dead pattern variable in invalidate_user/1; prefix was bare user_id which could match unintended keys — corrected to "#{user_id}:" to scope invalidation precisely

Changed — Design

• webhook_handler.ex + application.ex — Replaced Application.put_env handler registry with an ETS :bag table (:tink_webhook_handlers) created at application start; concurrent-safe, survives config reloads, supports multiple handlers per event type

Changed — Structure

• account_check.ex, balance_check.ex — Replaced duplicate auth, user, and credential functions (copied verbatim from Tink.Users / Tink.Accounts) with defdelegate — single source of truth, eliminates maintenance divergence risk
• transactions.ex — Replaced duplicate list_accounts implementation with defdelegate list_accounts(client, opts \\ []), to: Tink.Accounts
• providers.ex — Removed unused Cache alias; replaced private build_url / build_query_params helpers with Helpers.build_url; added explicit Cache.fetch/3 for cacheable reads
• client.ex — Rewrote cacheable?/1 using module-level @cacheable_patterns and @non_cacheable_patterns compile-time constants; fixed detect_resource_type/1 ordering so specific patterns are matched before catch-all ones
• retry.ex — default_retry?/1 now delegates to should_retry?/1 instead of duplicating logic; log_no_retry/2 gated on Config.debug_mode?() to match log_retry/2 symmetrically
• users.ex — Removed redundant Cache.invalidate_user/1 call in refresh_credential/2 — invalidation already handled by the underlying credential update path

March 11 — Cache Integration, Dialyzer, Best Practices, Project Config

Added — Cache Integration

Explicit Cache.fetch/3 added to all cacheable read operations across seven domain modules. Each module owns its own cache keys and TTLs; Client.get automatic caching is retained only as a fallback. All cache calls pass cache: false to Client.get to prevent double-caching. Cache is skipped when client.cache is falsy or Cache.enabled?() returns false.

Cache keys follow the pattern "scope:resource:qualifier" with "list" / "item" disambiguators to prevent key collisions between list and single-item queries.

Fixed — Dialyzer

• account_check.ex:357 — is_binary(binary) guard on a value typed as map() can never succeed; removed the unreachable guard and split the PDF-map and plain-map branches
• application.ex — @transport_opts module attribute cannot store the closure returned by :public_key.pkix_verify_hostname_match_fun/1 (Elixir only escapes static terms); replaced with a compile-time if @env == :prod do … end block emitting two defp transport_opts/0 clauses — eliminates the ArgumentError while retaining compile-time branch selection
• application.ex — case @env do with a compile-time @env caused dead-branch warnings for non-current environments; replaced with @pool_count and @default_pool_size compile-time module attributes to eliminate the branching entirely
• auth.ex:258 — Referenced Tink.health_check/1 which does not exist; replaced with Client.get(client, "/api/v1/user", cache: false)
• balance_check.ex:68 — alias Tink.Helpers was unused; removed
• connectivity.ex:505 — {:error, reason} match clause was unreachable given the success type of the preceding call; removed
• http_adapter.ex:229 — decode_response(%{body: _body}) fallback unreachable because Finch always returns a binary body; removed dead clause
• rate_limiter.ex — Full rewrite: bare Hammer.check_rate/3, inspect_bucket/3, delete_buckets/1 calls (Hammer v5/v6 API that no longer exists in 7.x) replaced with Hammer 7.2 use Hammer, backend: :ets, algorithm: :fix_window named-backend pattern using Backend.hit/3 and Backend.get/2; backend process added to Tink.Application supervision tree

Changed — Best Practices

• client.ex — Removed unused Config and HTTPAdapter aliases
• http_adapter.ex — Added @spec to all 6 @impl true behaviour callbacks

• application.ex — Added @spec start(Application.start_type(), term()) :: {:ok, pid()} | {:error, term()}

• error.ex — Replaced IO.inspect(error) in @moduledoc example with Logger.error/1
• 18 domain modules — Added 52 missing @spec annotations to public helper functions
• categories.ex, accounts.ex — Added "list" / "item" cache key disambiguators to eliminate collision risk between list-query and single-item cache entries

Added — Project Scaffolding

• mix.exs — Corrected app name :tink → :tink; module prefix Tink.* → Tink.* throughout; added :public_key to extra_applications; groups_for_modules updated with all actual module names and a new Webhooks group; extras expanded to cover all guide paths
• .formatter.exs — Set line_length: 120; added defdelegate: 2 to locals_without_parens
• .credo.exs — strict: true; MaxLineLength aligned to 120; per-check rationale comments for all disabled entries; included paths tightened for a single-app library
• .dialyzer_ignore.exs — Documented suppressions for all 5 known benign Dialyzer warnings
• README.md — Hex badge, feature overview, quick-start snippet, full product table, configuration reference
• LICENSE — MIT
• 19 documentation guides across guides/, guides/products/, and guides/advanced/

[0.1.0] - 2025-03-01

Initial release — empty Elixir package published to Hex.pm to reserve the tink package name.