enhanced alert granularity with min/max thresholds

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.gitea/workflows/check.yml

@@ -1,9 +0,0 @@
-name: check
-on: [push]
-jobs:
-    check:
-        runs-on: ubuntu-latest
-        steps:
-            # actions/checkout v4.2.2, 2026-02-22
-            - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
-            - run: docker build .

.gitignore

@@ -21,7 +21,7 @@ node_modules/
 *.key
 
 # Go build artifacts
-backend-go/bin/
+backend/bin/
 *.exe
 *.exe~
 *.dll

.prettierignore

@@ -1,7 +1,7 @@
 node_modules/
 frontend/dist/
 frontend/build/
-backend-go/bin/
+backend/bin/
 *.lock
 Prompts/
 .claude/

LICENSE

@@ -2,8 +2,7 @@ MIT License
 
 Copyright (c) 2026 Steven Jannette
 
-Permission is hereby granted, free of charge, to any person obtaining a copy
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal
-of this software and associated documentation files (the "Software"), to deal
 in the Software without restriction, including without limitation the rights
 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 copies of the Software, and to permit persons to whom the Software is

Makefile

@@ -2,7 +2,7 @@
         test-go test-js lint-go lint-js fmt-go fmt-js fmt-check-go fmt-check-js \
         build-go build-js
 
-GODIR    := backend-go
+GODIR    := backend
 JSDIR    := frontend
 PRETTIER := $(JSDIR)/node_modules/.bin/prettier
 

README.md

@@ -28,8 +28,8 @@ make hooks
 cd frontend && npm install && cd ..
 
 # Copy and fill in environment variables
-cp backend-go/.env.example backend-go/.env
+cp backend/.env.example backend/.env
-# edit backend-go/.env with your DATABASE_URL, FIREBASE_PROJECT_ID, ETH_RPC_URL
+# edit backend/.env with your DATABASE_URL, FIREBASE_PROJECT_ID, ETH_RPC_URL
 
 # Run checks (requires golangci-lint)
 make check
@@ -38,7 +38,7 @@ make check
 make run
 
 # Start the poller (separate terminal)
-cd backend-go && go run ./cmd/poller
+cd backend && go run ./cmd/poller
 
 # Start the frontend dev server (separate terminal)
 cd frontend && npm run dev
@@ -63,7 +63,7 @@ frontend:
 
 ```
 koin_ping_0.2.0/
-├── backend-go/                # Go monorepo root
+├── backend/                # Go monorepo root
 │   ├── cmd/api/               # HTTP REST API server
 │   ├── cmd/poller/            # Blockchain polling daemon
 │   └── internal/

REPO_POLICIES.md

@@ -1,188 +0,0 @@
----
-title: Repository Policies
-last_modified: 2026-02-22
----
-
-This document covers repository structure, tooling, and workflow standards. Code
-style conventions are in separate documents:
-
-- [Code Styleguide](https://git.eeqj.de/sneak/prompts/raw/branch/main/prompts/CODE_STYLEGUIDE.md)
-  (general, bash, Docker)
-- [Go](https://git.eeqj.de/sneak/prompts/raw/branch/main/prompts/CODE_STYLEGUIDE_GO.md)
-- [JavaScript](https://git.eeqj.de/sneak/prompts/raw/branch/main/prompts/CODE_STYLEGUIDE_JS.md)
-- [Python](https://git.eeqj.de/sneak/prompts/raw/branch/main/prompts/CODE_STYLEGUIDE_PYTHON.md)
-- [Go HTTP Server Conventions](https://git.eeqj.de/sneak/prompts/raw/branch/main/prompts/GO_HTTP_SERVER_CONVENTIONS.md)
-
----
-
-- Cross-project documentation (such as this file) must include
-  `last_modified: YYYY-MM-DD` in the YAML front matter so it can be kept in sync
-  with the authoritative source as policies evolve.
-
-- **ALL external references must be pinned by cryptographic hash.** This
-  includes Docker base images, Go modules, npm packages, GitHub Actions, and
-  anything else fetched from a remote source. Version tags (`@v4`, `@latest`,
-  `:3.21`, etc.) are server-mutable and therefore remote code execution
-  vulnerabilities. The ONLY acceptable way to reference an external dependency
-  is by its content hash (Docker `@sha256:...`, Go module hash in `go.sum`, npm
-  integrity hash in lockfile, GitHub Actions `@<commit-sha>`). No exceptions.
-  This also means never `curl | bash` to install tools like pyenv, nvm, rustup,
-  etc. Instead, download a specific release archive from GitHub, verify its hash
-  (hardcoded in the Dockerfile or script), and only then install. Unverified
-  install scripts are arbitrary remote code execution. This is the single most
-  important rule in this document. Double-check every external reference in
-  every file before committing. There are zero exceptions to this rule.
-
-- Every repo with software must have a root `Makefile` with these targets:
-  `make test`, `make lint`, `make fmt` (writes), `make fmt-check` (read-only),
-  `make check` (prereqs: `test`, `lint`, `fmt-check`), `make docker`, and
-  `make hooks` (installs pre-commit hook). A model Makefile is at
-  `https://git.eeqj.de/sneak/prompts/raw/branch/main/Makefile`.
-
-- Always use Makefile targets (`make fmt`, `make test`, `make lint`, etc.)
-  instead of invoking the underlying tools directly. The Makefile is the single
-  source of truth for how these operations are run.
-
-- The Makefile is authoritative documentation for how the repo is used. Beyond
-  the required targets above, it should have targets for every common operation:
-  running a local development server (`make run`, `make dev`), re-initializing
-  or migrating the database (`make db-reset`, `make migrate`), building
-  artifacts (`make build`), generating code, seeding data, or anything else a
-  developer would do regularly. If someone checks out the repo and types
-  `make<tab>`, they should see every meaningful operation available. A new
-  contributor should be able to understand the entire development workflow by
-  reading the Makefile.
-
-- Every repo should have a `Dockerfile`. All Dockerfiles must run `make check`
-  as a build step so the build fails if the branch is not green. For non-server
-  repos, the Dockerfile should bring up a development environment and run
-  `make check`. For server repos, `make check` should run as an early build
-  stage before the final image is assembled.
-
-- Every repo should have a Gitea Actions workflow (`.gitea/workflows/`) that
-  runs `docker build .` on push. Since the Dockerfile already runs `make check`,
-  a successful build implies all checks pass.
-
-- Use platform-standard formatters: `black` for Python, `prettier` for
-  JS/CSS/Markdown/HTML, `go fmt` for Go. Always use default configuration with
-  two exceptions: four-space indents (except Go), and `proseWrap: always` for
-  Markdown (hard-wrap at 80 columns). Documentation and writing repos (Markdown,
-  HTML, CSS) should also have `.prettierrc` and `.prettierignore`.
-
-- Pre-commit hook: `make check` if local testing is possible, otherwise
-  `make lint && make fmt-check`. The Makefile should provide a `make hooks`
-  target to install the pre-commit hook.
-
-- All repos with software must have tests that run via the platform-standard
-  test framework (`go test`, `pytest`, `jest`/`vitest`, etc.). If no meaningful
-  tests exist yet, add the most minimal test possible — e.g. importing the
-  module under test to verify it compiles/parses. There is no excuse for
-  `make test` to be a no-op.
-
-- `make test` must complete in under 20 seconds. Add a 30-second timeout in the
-  Makefile.
-
-- Docker builds must complete in under 5 minutes.
-
-- `make check` must not modify any files in the repo. Tests may use temporary
-  directories.
-
-- `main` must always pass `make check`, no exceptions.
-
-- Never commit secrets. `.env` files, credentials, API keys, and private keys
-  must be in `.gitignore`. No exceptions.
-
-- `.gitignore` should be comprehensive from the start: OS files (`.DS_Store`),
-  editor files (`.swp`, `*~`), language build artifacts, and `node_modules/`.
-  Fetch the standard `.gitignore` from
-  `https://git.eeqj.de/sneak/prompts/raw/branch/main/.gitignore` when setting up
-  a new repo.
-
-- Never use `git add -A` or `git add .`. Always stage files explicitly by name.
-
-- Never force-push to `main`.
-
-- Make all changes on a feature branch. You can do whatever you want on a
-  feature branch.
-
-- `.golangci.yml` is standardized and must _NEVER_ be modified by an agent, only
-  manually by the user. Fetch from
-  `https://git.eeqj.de/sneak/prompts/raw/branch/main/.golangci.yml`.
-
-- When pinning images or packages by hash, add a comment above the reference
-  with the version and date (YYYY-MM-DD).
-
-- Use `yarn`, not `npm`.
-
-- Write all dates as YYYY-MM-DD (ISO 8601).
-
-- Simple projects should be configured with environment variables.
-
-- Dockerized web services listen on port 8080 by default, overridable with
-  `PORT`.
-
-- `README.md` is the primary documentation. Required sections:
-    - **Description**: First line must include the project name, purpose,
-      category (web server, SPA, CLI tool, etc.), license, and author. Example:
-      "µPaaS is an MIT-licensed Go web application by @sneak that receives
-      git-frontend webhooks and deploys applications via Docker in realtime."
-    - **Getting Started**: Copy-pasteable install/usage code block.
-    - **Rationale**: Why does this exist?
-    - **Design**: How is the program structured?
-    - **TODO**: Update meticulously, even between commits. When planning, put
-      the todo list in the README so a new agent can pick up where the last one
-      left off.
-    - **License**: MIT, GPL, or WTFPL. Ask the user for new projects. Include a
-      `LICENSE` file in the repo root and a License section in the README.
-    - **Author**: [@sneak](https://sneak.berlin).
-
-- First commit of a new repo should contain only `README.md`.
-
-- Go module root: `sneak.berlin/go/<name>`. Always run `go mod tidy` before
-  committing.
-
-- Use SemVer.
-
-- Database migrations live in `internal/db/migrations/` and must be embedded in
-  the binary.
-    - `000_migration.sql` — contains ONLY the creation of the migrations
-      tracking table itself. Nothing else.
-    - `001_schema.sql` — the full application schema.
-    - **Pre-1.0.0:** never add additional migration files (002, 003, etc.).
-      There is no installed base to migrate. Edit `001_schema.sql` directly.
-    - **Post-1.0.0:** add new numbered migration files for each schema change.
-      Never edit existing migrations after release.
-
-- All repos should have an `.editorconfig` enforcing the project's indentation
-  settings.
-
-- Avoid putting files in the repo root unless necessary. Root should contain
-  only project-level config files (`README.md`, `Makefile`, `Dockerfile`,
-  `LICENSE`, `.gitignore`, `.editorconfig`, `REPO_POLICIES.md`, and
-  language-specific config). Everything else goes in a subdirectory. Canonical
-  subdirectory names:
-    - `bin/` — executable scripts and tools
-    - `cmd/` — Go command entrypoints
-    - `configs/` — configuration templates and examples
-    - `deploy/` — deployment manifests (k8s, compose, terraform)
-    - `docs/` — documentation and markdown (README.md stays in root)
-    - `internal/` — Go internal packages
-    - `internal/db/migrations/` — database migrations
-    - `pkg/` — Go library packages
-    - `share/` — systemd units, data files
-    - `static/` — static assets (images, fonts, etc.)
-    - `web/` — web frontend source
-
-- When setting up a new repo, files from the `prompts` repo may be used as
-  templates. Fetch them from
-  `https://git.eeqj.de/sneak/prompts/raw/branch/main/<path>`.
-
-- New repos must contain at minimum:
-    - `README.md`, `.git`, `.gitignore`, `.editorconfig`
-    - `LICENSE`, `REPO_POLICIES.md` (copy from the `prompts` repo)
-    - `Makefile`
-    - `Dockerfile`, `.dockerignore`
-    - `.gitea/workflows/check.yml`
-    - Go: `go.mod`, `go.sum`, `.golangci.yml`
-    - JS: `package.json`, `yarn.lock`, `.prettierrc`, `.prettierignore`
-    - Python: `pyproject.toml`

backend-go/.env.example

@@ -1,20 +0,0 @@
-# Server
-PORT=3001
-API_BASE_PATH=/v1
-NODE_ENV=development
-
-# Database
-DATABASE_URL=postgresql://user:password@localhost:5432/koin_ping
-
-# Ethereum JSON-RPC
-ETH_RPC_URL=https://mainnet.infura.io/v3/YOUR-PROJECT-ID
-
-# Polling interval (ms, minimum 1000)
-POLL_INTERVAL_MS=60000
-
-# Firebase
-FIREBASE_PROJECT_ID=koin-ping
-
-# Email notifications (Resend — https://resend.com)
-# RESEND_API_KEY=re_xxxxxxxxxxxx
-# EMAIL_FROM=Koin Ping <alerts@yourdomain.com>

backend-go/internal/notifications/notifier.go

@@ -1,16 +0,0 @@
-package notifications
-
-import "context"
-
-// AlertMetadata holds context about the alert being sent.
-type AlertMetadata struct {
-	TxHash       string
-	AddressLabel string
-	AlertType    string
-	Address      string
-}
-
-// Notifier is the interface implemented by all notification channels.
-type Notifier interface {
-	Send(ctx context.Context, message string, meta AlertMetadata) error
-}

backend/README.md

@@ -2,16 +2,16 @@ Start DB:
 
 brew services start postgresql@15
 
-From the backend-go directory, you have a few options:
+From the backend directory, you have a few options:
 
 Option 1: Single command (both API + poller)
-cd /Users/kjannette/workspace/koin_ping_0.2.0/backend-gomake dev-all
+cd /Users/kjannette/workspace/koin_ping_0.2.0/backendmake dev-all
 
 Option 2: Two separate terminals
 Terminal 1 (API server):
-cd /Users/kjannette/workspace/koin_ping_0.2.0/backend-go go run ./cmd/api
+cd /Users/kjannette/workspace/koin_ping_0.2.0/backend go run ./cmd/api
 Terminal 2 (Poller):
-cd /Users/kjannette/workspace/koin_ping_0.2.0/backend-go go run ./cmd/poller
+cd /Users/kjannette/workspace/koin_ping_0.2.0/backend go run ./cmd/poller
 
 make run — Builds and runs the API server.
 make dev — Runs the API server with auto-reload via air (falls back to go run if air isn't installed).

backend/cmd/api/main.go

@@ -8,13 +8,13 @@ import (
 	"time"
 
 	"github.com/joho/godotenv"
-	"github.com/kjannette/koin-ping/backend-go/internal/config"
+	"github.com/kjannette/koin-ping/backend/internal/config"
-	"github.com/kjannette/koin-ping/backend-go/internal/database"
+	"github.com/kjannette/koin-ping/backend/internal/database"
-	"github.com/kjannette/koin-ping/backend-go/internal/firebase"
+	"github.com/kjannette/koin-ping/backend/internal/firebase"
-	"github.com/kjannette/koin-ping/backend-go/internal/handlers"
+	"github.com/kjannette/koin-ping/backend/internal/handlers"
-	"github.com/kjannette/koin-ping/backend-go/internal/middleware"
+	"github.com/kjannette/koin-ping/backend/internal/middleware"
-	"github.com/kjannette/koin-ping/backend-go/internal/models"
+	"github.com/kjannette/koin-ping/backend/internal/models"
-	"github.com/kjannette/koin-ping/backend-go/internal/services"
+	"github.com/kjannette/koin-ping/backend/internal/services"
 )
 
 const (
@@ -62,6 +62,7 @@ func main() {
 	emailDigestHandler := handlers.NewEmailDigestHandler(emailDigestSvc, notifConfigModel)
 	statusHandler := handlers.NewStatusHandler(checkpointModel)
 	stripeHandler := handlers.NewStripeHandler(userModel, cfg)
+	accountHandler := handlers.NewAccountHandler(userModel, cfg)
 
 	authenticate := middleware.Authenticate(userModel)
 	requireSub := middleware.RequireSubscription(userModel)
@@ -88,6 +89,12 @@ func main() {
 		authenticate(http.HandlerFunc(stripeHandler.GetSubscriptionStatus)))
 	mux.Handle("POST "+b+"/stripe/verify-checkout",
 		authenticate(http.HandlerFunc(stripeHandler.VerifyCheckoutSession)))
+	mux.Handle("POST "+b+"/stripe/create-portal-session",
+		authenticate(http.HandlerFunc(stripeHandler.CreatePortalSession)))
+
+	// Account route (auth required, NO subscription required)
+	mux.Handle("GET "+b+"/user/account",
+		authenticate(http.HandlerFunc(accountHandler.GetAccount)))
 
 	// Authenticated + subscribed routes — addresses
 	mux.Handle("POST "+b+"/addresses",

backend/cmd/poller/main.go

@@ -12,11 +12,11 @@ import (
 	"time"
 
 	"github.com/joho/godotenv"
-	"github.com/kjannette/koin-ping/backend-go/internal/config"
+	"github.com/kjannette/koin-ping/backend/internal/config"
-	"github.com/kjannette/koin-ping/backend-go/internal/database"
+	"github.com/kjannette/koin-ping/backend/internal/database"
-	"github.com/kjannette/koin-ping/backend-go/internal/models"
+	"github.com/kjannette/koin-ping/backend/internal/models"
-	"github.com/kjannette/koin-ping/backend-go/internal/protocols/ethereum"
+	"github.com/kjannette/koin-ping/backend/internal/protocols/ethereum"
-	"github.com/kjannette/koin-ping/backend-go/internal/services"
+	"github.com/kjannette/koin-ping/backend/internal/services"
 )
 
 const (
@@ -138,6 +138,8 @@ func runCycle(
 		return
 	}
 
+	evaluator.WaitForNotifications()
+
 	duration := time.Since(startTime)
 	log.Printf("[%s] Cycle complete: %d observations, %d alerts fired in %s",
 		time.Now().UTC().Format(time.RFC3339),

backend/go.mod

@@ -1,4 +1,4 @@
-module github.com/kjannette/koin-ping/backend-go
+module github.com/kjannette/koin-ping/backend
 
 go 1.25.0
 

backend/infra/migrations/008_add_min_max_to_alert_rules.sql

@@ -0,0 +1,6 @@
+ALTER TABLE alert_rules ADD COLUMN minimum DECIMAL(20, 6);
+ALTER TABLE alert_rules ADD COLUMN maximum DECIMAL(20, 6);
+
+ALTER TABLE alert_rules ADD CONSTRAINT non_negative_minimum CHECK (minimum IS NULL OR minimum >= 0);
+ALTER TABLE alert_rules ADD CONSTRAINT non_negative_maximum CHECK (maximum IS NULL OR maximum >= 0);
+ALTER TABLE alert_rules ADD CONSTRAINT min_lte_max CHECK (minimum IS NULL OR maximum IS NULL OR minimum <= maximum);

backend/infra/schema.sql

@@ -35,6 +35,8 @@ CREATE TABLE alert_rules (
   address_id INTEGER NOT NULL REFERENCES addresses(id) ON DELETE CASCADE,
   type VARCHAR(50) NOT NULL,           -- 'incoming_tx', 'outgoing_tx', 'large_transfer', 'balance_below'
   threshold DECIMAL(20, 6),            -- ETH amount threshold (nullable for tx types that don't need it)
+  minimum DECIMAL(20, 6),              -- Optional min amount filter for incoming/outgoing alerts
+  maximum DECIMAL(20, 6),              -- Optional max amount filter for incoming/outgoing alerts
   enabled BOOLEAN DEFAULT TRUE,
   created_at TIMESTAMP DEFAULT NOW(),
 
@@ -44,7 +46,11 @@ CREATE TABLE alert_rules (
 
   CONSTRAINT positive_threshold CHECK (
     threshold IS NULL OR threshold > 0
-  )
+  ),
+
+  CONSTRAINT non_negative_minimum CHECK (minimum IS NULL OR minimum >= 0),
+  CONSTRAINT non_negative_maximum CHECK (maximum IS NULL OR maximum >= 0),
+  CONSTRAINT min_lte_max CHECK (minimum IS NULL OR maximum IS NULL OR minimum <= maximum)
 );
 
 

backend/internal/domain/types.go

@@ -47,7 +47,7 @@ var ThresholdRequiredTypes = []AlertType{ //nolint:gochecknoglobals
 	AlertBalanceBelow,
 }
 
-// IsValidAlertType returns true if the given string matches a known AlertType.
+// returns true if the given string matches a known AlertType.
 func IsValidAlertType(t string) bool {
 	for _, v := range ValidAlertTypes {
 		if string(v) == t {
@@ -58,7 +58,6 @@ func IsValidAlertType(t string) bool {
 	return false
 }
 
-// IsThresholdRequired returns true if the given AlertType requires a threshold.
 func IsThresholdRequired(t AlertType) bool {
 	for _, v := range ThresholdRequiredTypes {
 		if v == t {
@@ -74,6 +73,8 @@ type AlertRule struct {
 	AddressID int       `json:"address_id"` //nolint:tagliatelle
 	Type      AlertType `json:"type"`
 	Threshold *float64  `json:"threshold"`
+	Minimum   *float64  `json:"minimum"`
+	Maximum   *float64  `json:"maximum"`
 	Enabled   bool      `json:"enabled"`
 	CreatedAt time.Time `json:"created_at"` //nolint:tagliatelle
 }
@@ -93,7 +94,6 @@ type AddressCheckpoint struct {
 	LastCheckedAt    time.Time `json:"last_checked_at"`    //nolint:tagliatelle
 }
 
-// CheckpointDetail combines checkpoint and address info for reporting.
 type CheckpointDetail struct {
 	AddressID        int       `json:"address_id"`         //nolint:tagliatelle
 	Address          string    `json:"address"`
@@ -102,7 +102,7 @@ type CheckpointDetail struct {
 	LastCheckedAt    time.Time `json:"last_checked_at"`    //nolint:tagliatelle
 }
 
-// NotificationConfig holds a user's notification preferences.
+//  holds a user's notification preferences.
 type NotificationConfig struct {
 	UserID              string     `json:"user_id"`              //nolint:tagliatelle
 	DiscordWebhookURL   *string    `json:"discord_webhook_url"`  //nolint:tagliatelle
@@ -131,14 +131,12 @@ type NormalizedTx struct {
 	TokenValue    *string `json:"token_value,omitempty"`    //nolint:tagliatelle
 }
 
-// IsTokenTransfer returns true if this transaction represents an ERC-20 token transfer.
 func (tx NormalizedTx) IsTokenTransfer() bool {
 	return tx.TokenContract != nil
 }
 
 type Direction string
 
-// String implements fmt.Stringer.
 func (d Direction) String() string { return string(d) }
 
 const (

backend/internal/handlers/account.go

@@ -0,0 +1,66 @@
+package handlers
+
+import (
+	"log"
+	"net/http"
+	"time"
+
+	"github.com/kjannette/koin-ping/backend/internal/config"
+	"github.com/kjannette/koin-ping/backend/internal/middleware"
+	"github.com/kjannette/koin-ping/backend/internal/models"
+)
+
+type AccountHandler struct {
+	users *models.UserModel
+	cfg   *config.Config
+}
+
+func NewAccountHandler(users *models.UserModel, cfg *config.Config) *AccountHandler {
+	return &AccountHandler{users: users, cfg: cfg}
+}
+
+type accountResponse struct {
+	UserID             string  `json:"user_id"`
+	Email              string  `json:"email"`
+	UserName           string  `json:"user_name"`
+	SubscriptionStatus string  `json:"subscription_status"`
+	SubscriptionPlan   string  `json:"subscription_plan"`
+	MemberSince        *string `json:"member_since,omitempty"`
+	NextBillingDate    *string `json:"next_billing_date,omitempty"`
+	CancelAtPeriodEnd  bool    `json:"cancel_at_period_end"`
+	PeriodEndDate      *string `json:"period_end_date,omitempty"`
+}
+
+func (h *AccountHandler) GetAccount(w http.ResponseWriter, r *http.Request) {
+	userID := middleware.GetUserID(r.Context())
+	email := middleware.GetUserEmail(r.Context())
+
+	user, err := h.users.GetByID(r.Context(), userID)
+	if err != nil || user == nil {
+		log.Printf("Account: failed to get user %s: %v", userID, err)
+		writeError(w, http.StatusInternalServerError, "INTERNAL_ERROR", "Failed to load user")
+		return
+	}
+
+	resp := accountResponse{
+		UserID:             user.ID,
+		Email:              email,
+		UserName:           email,
+		SubscriptionStatus: user.SubscriptionStatus,
+		SubscriptionPlan:   "monthly/$1.99",
+	}
+
+	if user.SubscriptionCreatedAt != nil {
+		t := user.SubscriptionCreatedAt.Format(time.DateOnly)
+		resp.MemberSince = &t
+	}
+
+	// MOCKED: NextBillingDate, CancelAtPeriodEnd, PeriodEndDate.
+	// TODO: stripe-go v82 removed Subscription.CurrentPeriodEnd / CancelAtPeriodEnd.
+	// Research SubscriptionItem.CurrentPeriodEnd or use Stripe REST API directly.
+	resp.NextBillingDate = nil
+	resp.CancelAtPeriodEnd = false
+	resp.PeriodEndDate = nil
+
+	writeJSON(w, http.StatusOK, resp)
+}

backend/internal/handlers/address.go

@@ -8,9 +8,9 @@ import (
 	"regexp"
 	"strings"
 
-	"github.com/kjannette/koin-ping/backend-go/internal/domain"
+	"github.com/kjannette/koin-ping/backend/internal/domain"
-	"github.com/kjannette/koin-ping/backend-go/internal/middleware"
+	"github.com/kjannette/koin-ping/backend/internal/middleware"
-	"github.com/kjannette/koin-ping/backend-go/internal/models"
+	"github.com/kjannette/koin-ping/backend/internal/models"
 )
 
 var ethAddressRe = regexp.MustCompile(`^0x[a-fA-F0-9]{40}$`)

backend/internal/handlers/alert_event.go

@@ -5,9 +5,9 @@ import (
 	"net/http"
 	"strconv"
 
-	"github.com/kjannette/koin-ping/backend-go/internal/domain"
+	"github.com/kjannette/koin-ping/backend/internal/domain"
-	"github.com/kjannette/koin-ping/backend-go/internal/middleware"
+	"github.com/kjannette/koin-ping/backend/internal/middleware"
-	"github.com/kjannette/koin-ping/backend-go/internal/models"
+	"github.com/kjannette/koin-ping/backend/internal/models"
 )
 
 // AlertEventHandler handles HTTP requests for alert event history.

backend/internal/handlers/alert_rule.go

@@ -9,9 +9,9 @@ import (
 	"strconv"
 	"strings"
 
-	"github.com/kjannette/koin-ping/backend-go/internal/domain"
+	"github.com/kjannette/koin-ping/backend/internal/domain"
-	"github.com/kjannette/koin-ping/backend-go/internal/middleware"
+	"github.com/kjannette/koin-ping/backend/internal/middleware"
-	"github.com/kjannette/koin-ping/backend-go/internal/models"
+	"github.com/kjannette/koin-ping/backend/internal/models"
 )
 
 var errThresholdFormat = errors.New("unsupported threshold format")
@@ -37,6 +37,8 @@ func (h *AlertRuleHandler) Create(w http.ResponseWriter, r *http.Request) {
 	var body struct {
 		Type      string          `json:"type"`
 		Threshold json.RawMessage `json:"threshold"`
+		Minimum   json.RawMessage `json:"minimum"`
+		Maximum   json.RawMessage `json:"maximum"`
 	}
 	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
 		log.Printf("Failed to decode alert request body: %v", err)
@@ -53,6 +55,40 @@ func (h *AlertRuleHandler) Create(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	minimum, err := parseThreshold(body.Minimum)
+	if err != nil {
+		log.Printf("Failed to parse minimum: %v", err)
+		writeError(w, http.StatusBadRequest, "VALIDATION_ERROR", "minimum must be a valid number")
+
+		return
+	}
+
+	maximum, err := parseThreshold(body.Maximum)
+	if err != nil {
+		log.Printf("Failed to parse maximum: %v", err)
+		writeError(w, http.StatusBadRequest, "VALIDATION_ERROR", "maximum must be a valid number")
+
+		return
+	}
+
+	if minimum != nil && *minimum < 0 {
+		writeError(w, http.StatusBadRequest, "VALIDATION_ERROR", "minimum must be non-negative")
+
+		return
+	}
+
+	if maximum != nil && *maximum < 0 {
+		writeError(w, http.StatusBadRequest, "VALIDATION_ERROR", "maximum must be non-negative")
+
+		return
+	}
+
+	if minimum != nil && maximum != nil && *minimum > *maximum {
+		writeError(w, http.StatusBadRequest, "VALIDATION_ERROR", "minimum must not exceed maximum")
+
+		return
+	}
+
 	log.Printf("User %s creating alert: type=%s, addressID=%d", userID, body.Type, addressID)
 
 	if body.Type == "" {
@@ -96,7 +132,7 @@ func (h *AlertRuleHandler) Create(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	newAlert, err := h.alertRules.Create(r.Context(), addressID, alertType, threshold)
+	newAlert, err := h.alertRules.Create(r.Context(), addressID, alertType, threshold, minimum, maximum)
 	if err != nil {
 		log.Printf("Error creating alert rule: %v", err)
 		writeError(w, http.StatusInternalServerError, "INTERNAL_ERROR", "Failed to create alert rule")
@@ -182,7 +218,7 @@ func (h *AlertRuleHandler) ListByAddress(w http.ResponseWriter, r *http.Request)
 	writeJSON(w, http.StatusOK, alerts)
 }
 
-// UpdateStatus handles PATCH requests to enable or disable an alert rule.
+// UpdateStatus handles PATCH requests to enable/disable an alert rule and/or update min/max thresholds.
 func (h *AlertRuleHandler) UpdateStatus(w http.ResponseWriter, r *http.Request) {
 	userID := middleware.GetUserID(r.Context())
 	alertID, ok := parseIntParam(r.PathValue("alertId"))
@@ -194,6 +230,9 @@ func (h *AlertRuleHandler) UpdateStatus(w http.ResponseWriter, r *http.Request)
 
 	var body struct {
 		Enabled        *bool           `json:"enabled"`
+		Minimum        json.RawMessage `json:"minimum"`
+		Maximum        json.RawMessage `json:"maximum"`
+		UpdateMinMax   bool            `json:"update_min_max"`   //nolint:tagliatelle
 	}
 	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
 		log.Printf("Failed to decode update request body: %v", err)
@@ -204,8 +243,8 @@ func (h *AlertRuleHandler) UpdateStatus(w http.ResponseWriter, r *http.Request)
 
 	log.Printf("User %s updating alert ID: %d", userID, alertID)
 
-	if body.Enabled == nil {
+	if body.Enabled == nil && !body.UpdateMinMax {
-		writeError(w, http.StatusBadRequest, "VALIDATION_ERROR", "enabled must be a boolean value")
+		writeError(w, http.StatusBadRequest, "VALIDATION_ERROR", "must provide enabled (boolean) or update_min_max with minimum/maximum values")
 
 		return
 	}
@@ -224,7 +263,54 @@ func (h *AlertRuleHandler) UpdateStatus(w http.ResponseWriter, r *http.Request)
 		return
 	}
 
-	updated, err := h.alertRules.UpdateEnabled(r.Context(), alertID, *body.Enabled)
+	var updated *domain.AlertRule
+
+	if body.UpdateMinMax {
+		minimum, parseErr := parseThreshold(body.Minimum)
+		if parseErr != nil {
+			writeError(w, http.StatusBadRequest, "VALIDATION_ERROR", "minimum must be a valid number")
+
+			return
+		}
+
+		maximum, parseErr := parseThreshold(body.Maximum)
+		if parseErr != nil {
+			writeError(w, http.StatusBadRequest, "VALIDATION_ERROR", "maximum must be a valid number")
+
+			return
+		}
+
+		if minimum != nil && *minimum < 0 {
+			writeError(w, http.StatusBadRequest, "VALIDATION_ERROR", "minimum must be non-negative")
+
+			return
+		}
+
+		if maximum != nil && *maximum < 0 {
+			writeError(w, http.StatusBadRequest, "VALIDATION_ERROR", "maximum must be non-negative")
+
+			return
+		}
+
+		if minimum != nil && maximum != nil && *minimum > *maximum {
+			writeError(w, http.StatusBadRequest, "VALIDATION_ERROR", "minimum must not exceed maximum")
+
+			return
+		}
+
+		updated, err = h.alertRules.UpdateThresholds(r.Context(), alertID, minimum, maximum)
+		if err != nil {
+			log.Printf("Error updating alert thresholds: %v", err)
+			writeError(w, http.StatusInternalServerError, "INTERNAL_ERROR", "Failed to update alert")
+
+			return
+		}
+
+		log.Printf("Alert %d thresholds updated: min=%v, max=%v", alertID, minimum, maximum)
+	}
+
+	if body.Enabled != nil {
+		updated, err = h.alertRules.UpdateEnabled(r.Context(), alertID, *body.Enabled)
 		if err != nil {
 			log.Printf("Error updating alert: %v", err)
 			writeError(w, http.StatusInternalServerError, "INTERNAL_ERROR", "Failed to update alert")
@@ -233,6 +319,8 @@ func (h *AlertRuleHandler) UpdateStatus(w http.ResponseWriter, r *http.Request)
 		}
 
 		log.Printf("Alert %d updated: enabled=%v", alertID, *body.Enabled)
+	}
+
 	writeJSON(w, http.StatusOK, updated)
 }
 

backend/internal/handlers/email_digest.go

@@ -4,9 +4,9 @@ import (
 	"log"
 	"net/http"
 
-	"github.com/kjannette/koin-ping/backend-go/internal/middleware"
+	"github.com/kjannette/koin-ping/backend/internal/middleware"
-	"github.com/kjannette/koin-ping/backend-go/internal/models"
+	"github.com/kjannette/koin-ping/backend/internal/models"
-	"github.com/kjannette/koin-ping/backend-go/internal/services"
+	"github.com/kjannette/koin-ping/backend/internal/services"
 )
 
 type EmailDigestHandler struct {

backend/internal/handlers/notification_config.go

@@ -7,11 +7,11 @@ import (
 	"regexp"
 	"strings"
 
-	"github.com/kjannette/koin-ping/backend-go/internal/config"
+	"github.com/kjannette/koin-ping/backend/internal/config"
-	"github.com/kjannette/koin-ping/backend-go/internal/domain"
+	"github.com/kjannette/koin-ping/backend/internal/domain"
-	"github.com/kjannette/koin-ping/backend-go/internal/middleware"
+	"github.com/kjannette/koin-ping/backend/internal/middleware"
-	"github.com/kjannette/koin-ping/backend-go/internal/models"
+	"github.com/kjannette/koin-ping/backend/internal/models"
-	"github.com/kjannette/koin-ping/backend-go/internal/notifications"
+	"github.com/kjannette/koin-ping/backend/internal/notifications"
 )
 
 var emailRe = regexp.MustCompile(`^[^\s@]+@[^\s@]+\.[^\s@]+$`)

backend/internal/handlers/status.go

@@ -5,7 +5,7 @@ import (
 	"net/http"
 	"time"
 
-	"github.com/kjannette/koin-ping/backend-go/internal/models"
+	"github.com/kjannette/koin-ping/backend/internal/models"
 )
 
 // StatusHandler handles the system status endpoint.

backend/internal/handlers/stripe.go

@@ -7,12 +7,13 @@ import (
 	"net/http"
 
 	"github.com/stripe/stripe-go/v82"
+	portalsession "github.com/stripe/stripe-go/v82/billingportal/session"
 	checkoutsession "github.com/stripe/stripe-go/v82/checkout/session"
 	"github.com/stripe/stripe-go/v82/webhook"
 
-	"github.com/kjannette/koin-ping/backend-go/internal/config"
+	"github.com/kjannette/koin-ping/backend/internal/config"
-	"github.com/kjannette/koin-ping/backend-go/internal/middleware"
+	"github.com/kjannette/koin-ping/backend/internal/middleware"
-	"github.com/kjannette/koin-ping/backend-go/internal/models"
+	"github.com/kjannette/koin-ping/backend/internal/models"
 )
 
 const webhookMaxBodyBytes = 65536
@@ -139,6 +140,38 @@ func (h *StripeHandler) VerifyCheckoutSession(w http.ResponseWriter, r *http.Req
 	writeJSON(w, http.StatusOK, map[string]string{"subscription_status": "active"})
 }
 
+// CreatePortalSession creates a Stripe Billing Portal session so the user can
+// manage their subscription (cancel, update payment method, view invoices).
+func (h *StripeHandler) CreatePortalSession(w http.ResponseWriter, r *http.Request) {
+	userID := middleware.GetUserID(r.Context())
+
+	user, err := h.users.GetByID(r.Context(), userID)
+	if err != nil || user == nil {
+		log.Printf("Portal: failed to get user %s: %v", userID, err)
+		writeError(w, http.StatusInternalServerError, "INTERNAL_ERROR", "Failed to load user")
+		return
+	}
+
+	if user.StripeCustomerID == nil || *user.StripeCustomerID == "" {
+		writeError(w, http.StatusBadRequest, "NO_CUSTOMER", "No Stripe customer on file")
+		return
+	}
+
+	params := &stripe.BillingPortalSessionParams{
+		Customer:  user.StripeCustomerID,
+		ReturnURL: stripe.String(h.cfg.FrontendURL + "/account"),
+	}
+
+	s, err := portalsession.New(params)
+	if err != nil {
+		log.Printf("Portal: failed to create portal session: %v", err)
+		writeError(w, http.StatusInternalServerError, "STRIPE_ERROR", "Failed to create portal session")
+		return
+	}
+
+	writeJSON(w, http.StatusOK, map[string]string{"url": s.URL})
+}
+
 // HandleWebhook processes incoming Stripe webhook events.
 // This endpoint must NOT require authentication (Stripe calls it directly).
 func (h *StripeHandler) HandleWebhook(w http.ResponseWriter, r *http.Request) {

backend/internal/middleware/auth.go

@@ -8,8 +8,8 @@ import (
 	"net/http"
 	"strings"
 
-	fbauth "github.com/kjannette/koin-ping/backend-go/internal/firebase"
+	fbauth "github.com/kjannette/koin-ping/backend/internal/firebase"
-	"github.com/kjannette/koin-ping/backend-go/internal/models"
+	"github.com/kjannette/koin-ping/backend/internal/models"
 )
 
 type contextKey string

backend/internal/models/address.go

@@ -6,7 +6,7 @@ import (
 
 	"github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgxpool"
-	"github.com/kjannette/koin-ping/backend-go/internal/domain"
+	"github.com/kjannette/koin-ping/backend/internal/domain"
 )
 
 type AddressModel struct {

backend/internal/models/alert_event.go

@@ -6,7 +6,7 @@ import (
 
 	"github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgxpool"
-	"github.com/kjannette/koin-ping/backend-go/internal/domain"
+	"github.com/kjannette/koin-ping/backend/internal/domain"
 )
 
 type AlertEventModel struct {

backend/internal/models/alert_rule.go

@@ -6,7 +6,7 @@ import (
 
 	"github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgxpool"
-	"github.com/kjannette/koin-ping/backend-go/internal/domain"
+	"github.com/kjannette/koin-ping/backend/internal/domain"
 )
 
 type AlertRuleModel struct {
@@ -17,14 +17,14 @@ func NewAlertRuleModel(pool *pgxpool.Pool) *AlertRuleModel {
 	return &AlertRuleModel{pool: pool}
 }
 
-func (m *AlertRuleModel) Create(ctx context.Context, addressID int, alertType domain.AlertType, threshold *float64) (*domain.AlertRule, error) {
+func (m *AlertRuleModel) Create(ctx context.Context, addressID int, alertType domain.AlertType, threshold, minimum, maximum *float64) (*domain.AlertRule, error) {
 	var r domain.AlertRule
 	err := m.pool.QueryRow(ctx,
-		`INSERT INTO alert_rules (address_id, type, threshold, enabled)
+		`INSERT INTO alert_rules (address_id, type, threshold, minimum, maximum, enabled)
-		 VALUES ($1, $2, $3, TRUE)
+		 VALUES ($1, $2, $3, $4, $5, TRUE)
-		 RETURNING id, address_id, type, threshold, enabled, created_at`,
+		 RETURNING id, address_id, type, threshold, minimum, maximum, enabled, created_at`,
-		addressID, alertType.String(), threshold,
+		addressID, alertType.String(), threshold, minimum, maximum,
-	).Scan(&r.ID, &r.AddressID, &r.Type, &r.Threshold, &r.Enabled, &r.CreatedAt)
+	).Scan(&r.ID, &r.AddressID, &r.Type, &r.Threshold, &r.Minimum, &r.Maximum, &r.Enabled, &r.CreatedAt)
 	if err != nil {
 		return nil, err
 	}
@@ -33,7 +33,7 @@ func (m *AlertRuleModel) Create(ctx context.Context, addressID int, alertType do
 
 func (m *AlertRuleModel) ListByAddress(ctx context.Context, addressID int) ([]domain.AlertRule, error) {
 	rows, err := m.pool.Query(ctx,
-		`SELECT id, address_id, type, threshold, enabled, created_at
+		`SELECT id, address_id, type, threshold, minimum, maximum, enabled, created_at
 		 FROM alert_rules
 		 WHERE address_id = $1
 		 ORDER BY created_at DESC`,
@@ -47,7 +47,7 @@ func (m *AlertRuleModel) ListByAddress(ctx context.Context, addressID int) ([]do
 	var rules []domain.AlertRule
 	for rows.Next() {
 		var r domain.AlertRule
-		if err := rows.Scan(&r.ID, &r.AddressID, &r.Type, &r.Threshold, &r.Enabled, &r.CreatedAt); err != nil {
+		if err := rows.Scan(&r.ID, &r.AddressID, &r.Type, &r.Threshold, &r.Minimum, &r.Maximum, &r.Enabled, &r.CreatedAt); err != nil {
 			return nil, err
 		}
 		rules = append(rules, r)
@@ -61,19 +61,19 @@ func (m *AlertRuleModel) FindByID(ctx context.Context, id int, userID *string) (
 
 	if userID != nil {
 		err = m.pool.QueryRow(ctx,
-			`SELECT ar.id, ar.address_id, ar.type, ar.threshold, ar.enabled, ar.created_at
+			`SELECT ar.id, ar.address_id, ar.type, ar.threshold, ar.minimum, ar.maximum, ar.enabled, ar.created_at
 			 FROM alert_rules ar
 			 JOIN addresses a ON a.id = ar.address_id
 			 WHERE ar.id = $1 AND a.user_id = $2`,
 			id, *userID,
-		).Scan(&r.ID, &r.AddressID, &r.Type, &r.Threshold, &r.Enabled, &r.CreatedAt)
+		).Scan(&r.ID, &r.AddressID, &r.Type, &r.Threshold, &r.Minimum, &r.Maximum, &r.Enabled, &r.CreatedAt)
 	} else {
 		err = m.pool.QueryRow(ctx,
-			`SELECT id, address_id, type, threshold, enabled, created_at
+			`SELECT id, address_id, type, threshold, minimum, maximum, enabled, created_at
 			 FROM alert_rules
 			 WHERE id = $1`,
 			id,
-		).Scan(&r.ID, &r.AddressID, &r.Type, &r.Threshold, &r.Enabled, &r.CreatedAt)
+		).Scan(&r.ID, &r.AddressID, &r.Type, &r.Threshold, &r.Minimum, &r.Maximum, &r.Enabled, &r.CreatedAt)
 	}
 
 	if err != nil {
@@ -91,9 +91,27 @@ func (m *AlertRuleModel) UpdateEnabled(ctx context.Context, id int, enabled bool
 		`UPDATE alert_rules
 		 SET enabled = $2
 		 WHERE id = $1
-		 RETURNING id, address_id, type, threshold, enabled, created_at`,
+		 RETURNING id, address_id, type, threshold, minimum, maximum, enabled, created_at`,
 		id, enabled,
-	).Scan(&r.ID, &r.AddressID, &r.Type, &r.Threshold, &r.Enabled, &r.CreatedAt)
+	).Scan(&r.ID, &r.AddressID, &r.Type, &r.Threshold, &r.Minimum, &r.Maximum, &r.Enabled, &r.CreatedAt)
+	if err != nil {
+		if errors.Is(err, pgx.ErrNoRows) {
+			return nil, nil
+		}
+		return nil, err
+	}
+	return &r, nil
+}
+
+func (m *AlertRuleModel) UpdateThresholds(ctx context.Context, id int, minimum, maximum *float64) (*domain.AlertRule, error) {
+	var r domain.AlertRule
+	err := m.pool.QueryRow(ctx,
+		`UPDATE alert_rules
+		 SET minimum = $2, maximum = $3
+		 WHERE id = $1
+		 RETURNING id, address_id, type, threshold, minimum, maximum, enabled, created_at`,
+		id, minimum, maximum,
+	).Scan(&r.ID, &r.AddressID, &r.Type, &r.Threshold, &r.Minimum, &r.Maximum, &r.Enabled, &r.CreatedAt)
 	if err != nil {
 		if errors.Is(err, pgx.ErrNoRows) {
 			return nil, nil

backend/internal/models/checkpoint.go

@@ -7,7 +7,7 @@ import (
 
 	"github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgxpool"
-	"github.com/kjannette/koin-ping/backend-go/internal/domain"
+	"github.com/kjannette/koin-ping/backend/internal/domain"
 )
 
 type CheckpointModel struct {

backend/internal/models/notification_config.go

@@ -6,7 +6,7 @@ import (
 
 	"github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgxpool"
-	"github.com/kjannette/koin-ping/backend-go/internal/domain"
+	"github.com/kjannette/koin-ping/backend/internal/domain"
 )
 
 type NotificationConfigModel struct {

backend/internal/models/user.go

@@ -6,7 +6,7 @@ import (
 
 	"github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgxpool"
-	"github.com/kjannette/koin-ping/backend-go/internal/domain"
+	"github.com/kjannette/koin-ping/backend/internal/domain"
 )
 
 type UserModel struct {

backend/internal/notifications/discord.go

@@ -21,17 +21,14 @@ const (
 	colorBlue   = 0x0099ff
 )
 
-// discordHTTPClient is a shared HTTP client with a timeout for Discord requests.
 var discordHTTPClient = &http.Client{ //nolint:gochecknoglobals
 	Timeout: discordHTTPTimeoutSeconds * time.Second,
 }
 
-// DiscordNotifier sends alert notifications via a Discord webhook.
+//  sends alert notifications via a Discord webhook.
 type DiscordNotifier struct {
 	WebhookURL string
 }
-
-// Send implements Notifier for Discord.
 func (d *DiscordNotifier) Send(_ context.Context, message string, meta AlertMetadata) error {
 	_, err := SendDiscordNotification(d.WebhookURL, message, meta)
 	return err
@@ -104,8 +101,12 @@ func SendDiscordNotification(webhookURL, message string, meta AlertMetadata) (bo
 	defer resp.Body.Close()
 
 	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		err := fmt.Errorf("discord webhook failed: HTTP %d", resp.StatusCode)
 		log.Printf("Discord webhook failed: HTTP %d", resp.StatusCode)
-		return false, fmt.Errorf("discord webhook failed: HTTP %d", resp.StatusCode)
+		if isPermanentStatusCode(resp.StatusCode) {
+			return false, &PermanentError{Err: err}
+		}
+		return false, err
 	}
 
 	return true, nil

backend/internal/notifications/email.go

@@ -10,14 +10,12 @@ import (
 	"time"
 )
 
-// EmailNotifier sends alert notifications via email (Resend).
 type EmailNotifier struct {
 	APIKey string
 	From   string
 	To     string
 }
 
-// Send implements Notifier for email.
 func (e *EmailNotifier) Send(_ context.Context, message string, meta AlertMetadata) error {
 	_, err := SendEmailNotification(e.APIKey, e.From, e.To, message, meta)
 	return err
@@ -99,8 +97,12 @@ func SendEmailNotification(apiKey, fromAddress, toAddress, message string, meta
 	defer resp.Body.Close()
 
 	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		err := fmt.Errorf("resend API failed: HTTP %d", resp.StatusCode)
 		log.Printf("Resend API failed: HTTP %d", resp.StatusCode)
-		return false, fmt.Errorf("resend API failed: HTTP %d", resp.StatusCode)
+		if isPermanentStatusCode(resp.StatusCode) {
+			return false, &PermanentError{Err: err}
+		}
+		return false, err
 	}
 
 	return true, nil

backend/internal/notifications/notifier.go

@@ -0,0 +1,38 @@
+package notifications
+
+import (
+	"context"
+	"errors"
+	"net/http"
+)
+
+// AlertMetadata holds context about the alert being sent.
+type AlertMetadata struct {
+	TxHash       string
+	AddressLabel string
+	AlertType    string
+	Address      string
+}
+
+type Notifier interface {
+	Send(ctx context.Context, message string, meta AlertMetadata) error
+}
+
+// PermanentError wraps errors that should not be retried (e.g. 401, 403, 404).
+type PermanentError struct{ Err error }
+
+func (e *PermanentError) Error() string { return e.Err.Error() }
+func (e *PermanentError) Unwrap() error { return e.Err }
+
+func IsPermanent(err error) bool {
+	var p *PermanentError
+	return errors.As(err, &p)
+}
+
+func isPermanentStatusCode(code int) bool {
+	return code == http.StatusUnauthorized ||
+		code == http.StatusForbidden ||
+		code == http.StatusNotFound ||
+		code == http.StatusMethodNotAllowed ||
+		code == http.StatusGone
+}

backend/internal/notifications/slack.go

@@ -87,8 +87,12 @@ func SendSlackNotification(webhookURL, message string, meta AlertMetadata) (bool
 	defer resp.Body.Close()
 
 	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		err := fmt.Errorf("slack webhook failed: HTTP %d", resp.StatusCode)
 		log.Printf("Slack webhook failed: HTTP %d", resp.StatusCode)
-		return false, fmt.Errorf("slack webhook failed: HTTP %d", resp.StatusCode)
+		if isPermanentStatusCode(resp.StatusCode) {
+			return false, &PermanentError{Err: err}
+		}
+		return false, err
 	}
 
 	return true, nil

backend/internal/notifications/telegram.go

@@ -63,8 +63,12 @@ func SendTelegramNotification(botToken, chatID, message string, meta AlertMetada
 	defer resp.Body.Close()
 
 	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		err := fmt.Errorf("telegram API failed: HTTP %d", resp.StatusCode)
 		log.Printf("Telegram API failed: HTTP %d", resp.StatusCode)
-		return false, fmt.Errorf("telegram API failed: HTTP %d", resp.StatusCode)
+		if isPermanentStatusCode(resp.StatusCode) {
+			return false, &PermanentError{Err: err}
+		}
+		return false, err
 	}
 
 	return true, nil

backend/internal/protocols/ethereum/jsonrpc.go

@@ -12,18 +12,20 @@ import (
 	"strings"
 	"time"
 
-	"github.com/kjannette/koin-ping/backend-go/internal/domain"
+	"github.com/kjannette/koin-ping/backend/internal/domain"
 )
 
 const (
 	rpcTimeoutMS      = 30000
 	rpcMaxRetries     = 3
-	rpcRetryBaseMS  = 1000
+	rpcRetryBaseMS    = 2000
+	rpcMinIntervalMS  = 1000
 )
 
 type JsonRpcEthereum struct {
 	rpcURL     string
 	client     *http.Client
+	lastCallAt time.Time
 }
 
 func NewJsonRpcEthereum(rpcURL string) (*JsonRpcEthereum, error) {
@@ -58,6 +60,8 @@ type rpcError struct {
 }
 
 func (j *JsonRpcEthereum) callRPC(ctx context.Context, method string, params ...interface{}) (json.RawMessage, error) {
+	j.throttle(ctx)
+
 	if params == nil {
 		params = []interface{}{}
 	}
@@ -72,7 +76,25 @@ func (j *JsonRpcEthereum) callRPC(ctx context.Context, method string, params ...
 		return nil, fmt.Errorf("marshal RPC request: %w", err)
 	}
 
-	return j.callWithRetry(ctx, method, body)
+	result, callErr := j.callWithRetry(ctx, method, body)
+	j.lastCallAt = time.Now()
+
+	return result, callErr
+}
+
+func (j *JsonRpcEthereum) throttle(ctx context.Context) {
+	if j.lastCallAt.IsZero() {
+		return
+	}
+	minInterval := time.Duration(rpcMinIntervalMS) * time.Millisecond
+	elapsed := time.Since(j.lastCallAt)
+	if elapsed >= minInterval {
+		return
+	}
+	select {
+	case <-ctx.Done():
+	case <-time.After(minInterval - elapsed):
+	}
 }
 
 // callWithRetry executes a JSON-RPC POST with exponential backoff on transient errors.

backend/internal/protocols/ethereum/observer.go

@@ -3,7 +3,7 @@ package ethereum
 import (
 	"context"
 
-	"github.com/kjannette/koin-ping/backend-go/internal/domain"
+	"github.com/kjannette/koin-ping/backend/internal/domain"
 )
 
 // EthereumObserver defines the interface for blockchain interaction.

backend/internal/services/email_digest.go

@@ -9,7 +9,7 @@ import (
 	"net/http"
 	"time"
 
-	"github.com/kjannette/koin-ping/backend-go/internal/models"
+	"github.com/kjannette/koin-ping/backend/internal/models"
 )
 
 const (
@@ -20,7 +20,7 @@ const (
 
 var digestHTTPClient = &http.Client{Timeout: emailHTTPTimeout} //nolint:gochecknoglobals
 
-// EmailDigestService handles email setup and digest sending via Resend.
+// handles email setup and digest sending via Resend.
 type EmailDigestService struct {
 	apiKey      string
 	fromAddress string
@@ -66,7 +66,6 @@ func (s *EmailDigestService) SetupEmail(toAddress string) error {
 	return s.send(toAddress, "Koin Ping — Email Alerts Configured", html)
 }
 
-// SendDigest compiles recent alert events for a user and sends a digest email.
 func (s *EmailDigestService) SendDigest(ctx context.Context, userID, toAddress string) error {
 	if !s.Configured() {
 		return fmt.Errorf("email service not configured: RESEND_API_KEY not set") //nolint:err113
@@ -131,8 +130,6 @@ func (s *EmailDigestService) SendDigest(ctx context.Context, userID, toAddress s
 	return s.send(toAddress, subject, html)
 }
 
-// SendDigestsForAllUsers sends a digest email to every user that has
-// notifications enabled and an email configured.
 func (s *EmailDigestService) SendDigestsForAllUsers(ctx context.Context) (int, error) {
 	if !s.Configured() {
 		return 0, nil

backend/internal/services/evaluator.go

@@ -4,19 +4,23 @@ import (
 	"context"
 	"fmt"
 	"log"
+	"sync"
 	"time"
 
-	"github.com/kjannette/koin-ping/backend-go/internal/domain"
+	"golang.org/x/sync/semaphore"
-	"github.com/kjannette/koin-ping/backend-go/internal/models"
+
-	"github.com/kjannette/koin-ping/backend-go/internal/notifications"
+	"github.com/kjannette/koin-ping/backend/internal/domain"
-	"github.com/kjannette/koin-ping/backend-go/internal/protocols/ethereum"
+	"github.com/kjannette/koin-ping/backend/internal/models"
-	"github.com/kjannette/koin-ping/backend-go/internal/wei"
+	"github.com/kjannette/koin-ping/backend/internal/notifications"
+	"github.com/kjannette/koin-ping/backend/internal/protocols/ethereum"
+	"github.com/kjannette/koin-ping/backend/internal/wei"
 )
 
 const (
 	notificationTimeout    = 30 * time.Second
 	notificationMaxRetries = 3
 	notificationRetryBase  = time.Second
+	maxConcurrentNotifications = 5
 )
 
 type EvaluatorService struct {
@@ -27,6 +31,8 @@ type EvaluatorService struct {
 	notifConfigs *models.NotificationConfigModel
 	resendAPIKey string
 	emailFrom    string
+	notifSem     *semaphore.Weighted
+	notifWg      sync.WaitGroup
 }
 
 func NewEvaluatorService(
@@ -46,6 +52,7 @@ func NewEvaluatorService(
 		notifConfigs: notifConfigs,
 		resendAPIKey: resendAPIKey,
 		emailFrom:    emailFrom,
+		notifSem:     semaphore.NewWeighted(maxConcurrentNotifications),
 	}
 }
 
@@ -97,9 +104,9 @@ func (s *EvaluatorService) evaluateObservation(ctx context.Context, obs domain.O
 func (s *EvaluatorService) ruleMatches(ctx context.Context, rule domain.AlertRule, obs domain.ObservedTx) (bool, error) {
 	switch rule.Type {
 	case domain.AlertIncomingTx:
-		return obs.Direction == domain.DirectionIncoming, nil
+		return s.matchesDirectionalTx(rule, obs, domain.DirectionIncoming)
 	case domain.AlertOutgoingTx:
-		return obs.Direction == domain.DirectionOutgoing, nil
+		return s.matchesDirectionalTx(rule, obs, domain.DirectionOutgoing)
 	case domain.AlertLargeTransfer:
 		return s.matchesLargeTransfer(rule, obs)
 	case domain.AlertBalanceBelow:
@@ -110,6 +117,42 @@ func (s *EvaluatorService) ruleMatches(ctx context.Context, rule domain.AlertRul
 	}
 }
 
+func (s *EvaluatorService) matchesDirectionalTx(rule domain.AlertRule, obs domain.ObservedTx, expected domain.Direction) (bool, error) {
+	if obs.Direction != expected {
+		return false, nil
+	}
+
+	if rule.Minimum != nil {
+		minWei, err := wei.FromEth(*rule.Minimum)
+		if err != nil {
+			return false, err
+		}
+		aboveMin, err := wei.GreaterThanOrEqual(obs.Value, minWei)
+		if err != nil {
+			return false, err
+		}
+		if !aboveMin {
+			return false, nil
+		}
+	}
+
+	if rule.Maximum != nil {
+		maxWei, err := wei.FromEth(*rule.Maximum)
+		if err != nil {
+			return false, err
+		}
+		belowMax, err := wei.LessThanOrEqual(obs.Value, maxWei)
+		if err != nil {
+			return false, err
+		}
+		if !belowMax {
+			return false, nil
+		}
+	}
+
+	return true, nil
+}
+
 func (s *EvaluatorService) matchesLargeTransfer(rule domain.AlertRule, obs domain.ObservedTx) (bool, error) {
 	if rule.Threshold == nil {
 		return false, nil
@@ -189,7 +232,14 @@ func (s *EvaluatorService) fireAlert(ctx context.Context, rule domain.AlertRule,
 	if addr != nil {
 		userID := addr.UserID
 		address := addr.Address
+		if err := s.notifSem.Acquire(ctx, 1); err != nil {
+			log.Printf("Failed to acquire notification semaphore for rule %d: %v", rule.ID, err)
+			return nil
+		}
+		s.notifWg.Add(1)
 		go func() {
+			defer s.notifSem.Release(1)
+			defer s.notifWg.Done()
 			notifCtx, cancel := context.WithTimeout(context.Background(), notificationTimeout)
 			defer cancel()
 			s.sendNotification(notifCtx, userID, message, obs, addressLabel, rule, address)
@@ -199,6 +249,11 @@ func (s *EvaluatorService) fireAlert(ctx context.Context, rule domain.AlertRule,
 	return nil
 }
 
+// WaitForNotifications blocks until all in-flight notification goroutines finish.
+func (s *EvaluatorService) WaitForNotifications() {
+	s.notifWg.Wait()
+}
+
 func (s *EvaluatorService) buildNotifiers(cfg *domain.NotificationConfig) []notifications.Notifier {
 	var notifiers []notifications.Notifier
 
@@ -242,8 +297,14 @@ func sendWithRetry(ctx context.Context, n notifications.Notifier, message string
 		}
 
 		if err := n.Send(ctx, message, meta); err != nil {
-			log.Printf("Notification attempt %d/%d failed: %v", attempt+1, notificationMaxRetries, err)
 			lastErr = err
+
+			if notifications.IsPermanent(err) {
+				log.Printf("Permanent notification failure, skipping retries: %v", err)
+				return err
+			}
+
+			log.Printf("Notification attempt %d/%d failed: %v", attempt+1, notificationMaxRetries, err)
 			continue
 		}
 

backend/internal/services/observer.go

@@ -5,9 +5,9 @@ import (
 	"log"
 	"strings"
 
-	"github.com/kjannette/koin-ping/backend-go/internal/domain"
+	"github.com/kjannette/koin-ping/backend/internal/domain"
-	"github.com/kjannette/koin-ping/backend-go/internal/models"
+	"github.com/kjannette/koin-ping/backend/internal/models"
-	"github.com/kjannette/koin-ping/backend-go/internal/protocols/ethereum"
+	"github.com/kjannette/koin-ping/backend/internal/protocols/ethereum"
 )
 
 const maxBlocksPerRun = 100

backend/internal/wei/converter.go

@@ -90,6 +90,14 @@ func LessThan(weiA, weiB string) (bool, error) {
 	return cmp < 0, nil
 }
 
+func LessThanOrEqual(weiA, weiB string) (bool, error) {
+	cmp, err := Compare(weiA, weiB)
+	if err != nil {
+		return false, err
+	}
+	return cmp <= 0, nil
+}
+
 // FormatAsEth formats a Wei string as "X.XXXX ETH".
 func FormatAsEth(weiString string, decimals int) (string, error) {
 	eth, err := ToEth(weiString)

frontend/src/App.jsx

@@ -3,10 +3,11 @@ import { useAuth } from "./contexts/AuthContext";
 import Navbar from "./components/Navbar";
 import Login from "./pages/login/Login";
 import Signup from "./pages/Signup";
-import Subscribe from "./pages/subscribe/subscribe";
+import Subscribe from "./pages/subscribe/Subscribe";
 import Addresses from "./pages/addresses/Addresses";
 import Alerts from "./pages/alerts/Alerts";
 import AlertHistory from "./pages/alertHistory/AlertHistory";
+import Account from "./pages/user_account/Account";
 
 export default function App() {
   const { currentUser } = useAuth();
@@ -30,6 +31,7 @@ export default function App() {
         <Route path="/addresses" element={<Addresses />} />
         <Route path="/alerts" element={<Alerts />} />
         <Route path="/alertevents" element={<AlertHistory />} />
+        <Route path="/account" element={<Account />} />
         <Route path="/subscribe" element={<Subscribe />} />
         <Route path="*" element={<Navigate to="/addresses" />} />
       </Routes>

frontend/src/api/account.js

@@ -0,0 +1,25 @@
+import { getAuthHeaders } from "./authHeaders";
+import { API_BASE } from "./config";
+
+export async function getAccount() {
+    const headers = await getAuthHeaders();
+    const res = await fetch(`${API_BASE}/user/account`, { headers });
+    if (!res.ok) {
+        const data = await res.json();
+        throw new Error(data.message || "Failed to load account");
+    }
+    return res.json();
+}
+
+export async function createPortalSession() {
+    const headers = await getAuthHeaders();
+    const res = await fetch(`${API_BASE}/stripe/create-portal-session`, {
+        method: "POST",
+        headers,
+    });
+    if (!res.ok) {
+        const data = await res.json();
+        throw new Error(data.message || "Failed to create portal session");
+    }
+    return res.json();
+}

frontend/src/api/alerts.jsx

@@ -129,6 +129,48 @@ export async function updateAlertStatus(alertId, enabled) {
     }
 }
 
+/**
+ * Update the min/max thresholds on an alert rule
+ * @param {number} alertId - Alert rule ID
+ * @param {number|null} minimum - Minimum amount (null to clear)
+ * @param {number|null} maximum - Maximum amount (null to clear)
+ * @returns {Promise<Object>} Updated alert rule
+ */
+export async function updateAlertThresholds(alertId, minimum, maximum) {
+    try {
+        const headers = await getAuthHeaders();
+        const response = await fetch(`${API_BASE}/alerts/${alertId}`, {
+            method: "PATCH",
+            headers: headers,
+            body: JSON.stringify({
+                update_min_max: true,
+                minimum: minimum ?? null,
+                maximum: maximum ?? null,
+            }),
+        });
+
+        if (!response.ok) {
+            let errorMessage = "Failed to update alert thresholds";
+            try {
+                const error = await response.json();
+                errorMessage = error.message || errorMessage;
+            } catch {
+                errorMessage = `Server error: ${response.status} ${response.statusText}`;
+            }
+            throw new Error(errorMessage);
+        }
+
+        return response.json();
+    } catch (error) {
+        if (error.message.includes("fetch")) {
+            throw new Error(
+                "Cannot connect to server. Is the backend running?",
+            );
+        }
+        throw error;
+    }
+}
+
 /**
  * Delete an alert rule
  * @param {number} alertId - Alert rule ID

frontend/src/components/Navbar.css

@@ -8,6 +8,19 @@
   border-bottom: 1px solid var(--color-border-light);
 }
 
+/* ── Left Group: Brand + Links ───────────────────────────── */
+
+.navbar__left {
+  display: flex;
+  align-items: center;
+  gap: 0.5rem;
+}
+
+.navbar__brand-group {
+  display: flex;
+  align-items: center;
+}
+
 .navbar__brand {
   font-weight: 700;
   font-size: 1.4rem;
@@ -38,11 +51,33 @@
   background-color: var(--color-bg-card);
 }
 
+/* ── Right Group: Email + Logout + Hamburger ─────────────── */
+
+.navbar__right {
+  display: flex;
+  align-items: center;
+  gap: 1rem;
+}
+
 .navbar__user {
   font-size: 1.275rem;
   color: #777;
 }
 
+.navbar__user-link {
+  color: var(--color-primary);
+  text-decoration: none;
+  transition: color 0.15s ease;
+}
+
+.navbar__user-link:hover {
+  color: var(--color-primary-hover);
+}
+
+.navbar__user-link--mobile {
+  display: none;
+}
+
 .navbar__logout {
   padding: 0.4rem 1rem;
   font-size: 1.275rem;
@@ -54,3 +89,79 @@
   cursor: pointer;
   transition: all 0.15s ease;
 }
+
+/* ── Hamburger Icon (hidden on desktop) ──────────────────── */
+
+.navbar__hamburger {
+  display: none;
+  flex-direction: column;
+  justify-content: center;
+  gap: 5px;
+  background: none;
+  border: none;
+  cursor: pointer;
+  padding: 4px;
+}
+
+.navbar__hamburger-bar {
+  display: block;
+  width: 28px;
+  height: 3px;
+  background-color: var(--color-brand);
+  border-radius: 2px;
+}
+
+/* ── Responsive: Tablet & below (≤ 768px) ────────────────── */
+
+@media (max-width: 768px) {
+  .navbar {
+    padding: 0.75rem 1rem;
+  }
+
+  .navbar__brand-group {
+    flex-direction: column;
+    align-items: flex-start;
+  }
+
+  .navbar__brand {
+    margin-right: 0;
+    font-size: 1.25rem;
+  }
+
+  .navbar__links {
+    display: none;
+  }
+
+  .navbar__user-link--mobile {
+    display: block;
+    font-size: 0.95rem;
+  }
+
+  .navbar__user-link--desktop {
+    display: none;
+  }
+
+  .navbar__logout {
+    display: none;
+  }
+
+  .navbar__hamburger {
+    display: flex;
+  }
+}
+
+/* ── Responsive: Mobile (≤ 480px) ────────────────────────── */
+
+@media (max-width: 480px) {
+  .navbar {
+    padding: 0.75rem;
+  }
+
+  .navbar__brand {
+    font-size: 1.15rem;
+  }
+
+  .navbar__user-link--mobile {
+    font-size: 0.85rem;
+  }
+}

frontend/src/components/Navbar.jsx

@@ -1,5 +1,7 @@
+import { useState } from "react";
 import { Link, useLocation } from "react-router-dom";
 import { useAuth } from "../contexts/AuthContext";
+import NavPanel from "./navPanel/NavPanel";
 import "./Navbar.css";
 
 const navLinks = [
@@ -11,13 +13,20 @@ const navLinks = [
 export default function Navbar() {
   const { currentUser, logout } = useAuth();
   const location = useLocation();
+  const [isNavPanelOpen, setIsNavPanelOpen] = useState(false);
 
   if (!currentUser) return null;
 
   return (
+    <>
       <nav className="navbar">
-      <div className="flex flex--center gap-sm">
+        <div className="navbar__left">
+          <div className="navbar__brand-group">
             <span className="navbar__brand">Koin Ping</span>
+            <Link to="/account" className="navbar__user-link navbar__user-link--mobile">
+              {currentUser.email}
+            </Link>
+          </div>
           <div className="navbar__links">
             {navLinks.map(({ to, label }) => {
               const isActive = location.pathname === to;
@@ -34,12 +43,29 @@ export default function Navbar() {
           </div>
         </div>
 
-      <div className="flex flex--center gap-lg">
+        <div className="navbar__right">
-        <span className="navbar__user">{currentUser.email}</span>
+          <Link to="/account" className="navbar__user navbar__user-link navbar__user-link--desktop">
+            {currentUser.email}
+          </Link>
           <button onClick={logout} className="navbar__logout">
             Logout
           </button>
+          <button
+            className="navbar__hamburger"
+            onClick={() => setIsNavPanelOpen(true)}
+            aria-label="Open navigation menu"
+          >
+            <span className="navbar__hamburger-bar" />
+            <span className="navbar__hamburger-bar" />
+            <span className="navbar__hamburger-bar" />
+          </button>
         </div>
       </nav>
+
+      <NavPanel
+        isOpen={isNavPanelOpen}
+        onClose={() => setIsNavPanelOpen(false)}
+      />
+    </>
   );
 }

frontend/src/components/navPanel/NavPanel.css

@@ -0,0 +1,78 @@
+/* ── Overlay Backdrop ─────────────────────────────────────── */
+
+.nav-panel__overlay {
+  position: fixed;
+  inset: 0;
+  background-color: rgba(0, 0, 0, 0.45);
+  opacity: 0;
+  pointer-events: none;
+  transition: opacity 0.3s ease;
+  z-index: 900;
+}
+
+.nav-panel__overlay--visible {
+  opacity: 1;
+  pointer-events: auto;
+}
+
+/* ── Slide-out Panel ─────────────────────────────────────── */
+
+.nav-panel {
+  position: fixed;
+  top: 0;
+  left: 0;
+  width: 260px;
+  height: 100%;
+  background-color: var(--color-bg-elevated);
+  border-right: 1px solid var(--color-border);
+  transform: translateX(-100%);
+  transition: transform 0.3s ease;
+  z-index: 950;
+  display: flex;
+  flex-direction: column;
+  padding: 1.5rem 0;
+}
+
+.nav-panel--open {
+  transform: translateX(0);
+}
+
+/* ── Nav Links ───────────────────────────────────────────── */
+
+.nav-panel__nav {
+  display: flex;
+  flex-direction: column;
+  flex: 1;
+}
+
+.nav-panel__link {
+  padding: 0.9rem 1.5rem;
+  text-decoration: none;
+  font-size: 1.3rem;
+  font-weight: 200;
+  color: var(--color-text-subtle);
+  border-left: 3px solid transparent;
+  transition: background-color 0.15s ease, color 0.15s ease;
+}
+
+.nav-panel__link--active {
+  font-weight: 600;
+  color: var(--color-text);
+  background-color: var(--color-bg-card);
+  border-left-color: var(--color-brand);
+}
+
+/* ── Logout Button ───────────────────────────────────────── */
+
+.nav-panel__logout {
+  margin: 1rem 1.5rem;
+  padding: 0.5rem 1rem;
+  font-size: 1.15rem;
+  font-weight: 400;
+  background-color: transparent;
+  color: var(--color-text-subtle);
+  border: 1px solid var(--color-border);
+  border-radius: var(--radius-lg);
+  cursor: pointer;
+  transition: all 0.15s ease;
+}

frontend/src/components/navPanel/NavPanel.jsx

@@ -0,0 +1,52 @@
+import { Link, useLocation } from "react-router-dom";
+import { useAuth } from "../../contexts/AuthContext";
+import "./NavPanel.css";
+
+const navLinks = [
+  { to: "/addresses", label: "Addresses" },
+  { to: "/alerts", label: "Configure Alerts" },
+  { to: "/alertevents", label: "Alert Event History" },
+];
+
+export default function NavPanel({ isOpen, onClose }) {
+  const { logout } = useAuth();
+  const location = useLocation();
+
+  const handleNavClick = () => {
+    onClose();
+  };
+
+  const handleLogout = () => {
+    onClose();
+    logout();
+  };
+
+  return (
+    <>
+      <div
+        className={`nav-panel__overlay${isOpen ? " nav-panel__overlay--visible" : ""}`}
+        onClick={onClose}
+      />
+      <aside className={`nav-panel${isOpen ? " nav-panel--open" : ""}`}>
+        <nav className="nav-panel__nav">
+          {navLinks.map(({ to, label }) => {
+            const isActive = location.pathname === to;
+            return (
+              <Link
+                key={to}
+                to={to}
+                className={`nav-panel__link${isActive ? " nav-panel__link--active" : ""}`}
+                onClick={handleNavClick}
+              >
+                {label}
+              </Link>
+            );
+          })}
+        </nav>
+        <button onClick={handleLogout} className="nav-panel__logout">
+          Logout
+        </button>
+      </aside>
+    </>
+  );
+}

frontend/src/index.css

@@ -356,3 +356,73 @@ button {
   color: white;
   font-size: 0.85rem;
 }
+
+/* ── Responsive Breakpoints ──────────────────────────────── */
+/* Mobile:  <= 480px                                          */
+/* Tablet:  481px – 768px                                     */
+/* Laptop:  769px – 1024px                                    */
+/* Desktop: >= 1025px (default styles above)                  */
+
+/* Laptop & below */
+@media (max-width: 1024px) {
+  .page--wide {
+    max-width: 100%;
+  }
+}
+
+/* Tablet & below */
+@media (max-width: 768px) {
+  html {
+    font-size: 13px;
+  }
+
+  .page {
+    padding: 1.25rem;
+  }
+
+  .btn--lg {
+    padding: 0.6rem 1.2rem;
+  }
+
+  h1 {
+    font-size: 1.75rem;
+  }
+
+  h2 {
+    font-size: 1.4rem;
+  }
+
+  h3 {
+    font-size: 1.15rem;
+  }
+}
+
+/* Mobile */
+@media (max-width: 480px) {
+  html {
+    font-size: 12px;
+  }
+
+  .page {
+    padding: 1rem 0.75rem;
+  }
+
+  .form-control,
+  .form-select {
+    font-size: 0.95rem;
+  }
+
+  .btn {
+    padding: 0.45rem 0.85rem;
+    font-size: 0.95rem;
+  }
+
+  .btn--lg {
+    padding: 0.55rem 1rem;
+    font-size: 1rem;
+  }
+
+  .section {
+    padding: 0.75rem;
+  }
+}

frontend/src/pages/addresses/Addresses.css

@@ -28,3 +28,13 @@
   margin-left: 1rem;
   flex-shrink: 0;
 }
+
+/* ── Addresses Responsive ────────────────────────────────── */
+
+@media (max-width: 480px) {
+  .address__remove {
+    margin-left: 0.5rem;
+    padding: 0.25rem 0.5rem;
+    font-size: 0.8rem;
+  }
+}

frontend/src/pages/alerts/Alerts.css

@@ -51,6 +51,69 @@
   opacity: 0.6;
 }
 
+.alerts__accordion-toggle {
+  display: flex;
+  align-items: center;
+  gap: 0.5rem;
+  margin-top: 0.75rem;
+  padding: 0.5rem 0 0;
+  border-top: 1px solid var(--color-border);
+  cursor: pointer;
+  font-size: 0.85rem;
+  color: var(--color-text-muted);
+  background: none;
+  border-left: none;
+  border-right: none;
+  border-bottom: none;
+  width: 100%;
+  text-align: left;
+}
+
+.alerts__accordion-toggle:hover {
+  color: var(--color-text);
+}
+
+.alerts__accordion-chevron {
+  display: inline-block;
+  transition: transform 0.2s ease;
+  font-size: 0.7rem;
+}
+
+.alerts__accordion-chevron--open {
+  transform: rotate(90deg);
+}
+
+.alerts__accordion-panel {
+  overflow: hidden;
+  max-height: 0;
+  opacity: 0;
+  transition: max-height 0.25s ease, opacity 0.2s ease, padding 0.25s ease;
+  padding: 0 0.25rem;
+}
+
+.alerts__accordion-panel--open {
+  max-height: 200px;
+  opacity: 1;
+  padding: 0.75rem 0.25rem 0.25rem;
+}
+
+.alerts__threshold-inputs {
+  display: flex;
+  gap: 1rem;
+  align-items: flex-end;
+}
+
+.alerts__threshold-inputs .form-field {
+  flex: 1;
+  margin-bottom: 0;
+}
+
+.alerts__threshold-actions {
+  display: flex;
+  gap: 0.5rem;
+  margin-top: 0.5rem;
+}
+
 .alerts__email-buttons {
   display: flex;
   gap: 0.5rem;
@@ -61,3 +124,54 @@
   gap: 0.75rem;
   margin-top: 1rem;
 }
+
+/* ── Alerts Page Responsive ──────────────────────────────── */
+
+/* Laptop: tighten the gap */
+@media (max-width: 1024px) {
+  .alerts-grid {
+    gap: 1.5rem;
+  }
+}
+
+/* Tablet & below: collapse to single column */
+@media (max-width: 768px) {
+  .alerts-grid {
+    grid-template-columns: 1fr;
+    gap: 2.5rem;
+  }
+}
+
+/* Mobile: compact spacing */
+@media (max-width: 480px) {
+  .alerts-grid {
+    gap: 2rem;
+  }
+
+  .alerts__address-info {
+    padding: 0.75rem;
+    margin-bottom: 1.25rem;
+  }
+
+  .alerts__rule {
+    padding: 0.75rem;
+  }
+
+  .alerts__rule .flex--between {
+    flex-direction: column;
+    gap: 0.75rem;
+  }
+
+  .alerts__save-test {
+    flex-direction: column;
+  }
+
+  .alerts__save-test .btn--lg {
+    width: 100%;
+    text-align: center;
+  }
+
+  .alerts__email-buttons {
+    flex-direction: column;
+  }
+}

frontend/src/pages/alerts/Alerts.jsx

@@ -7,6 +7,7 @@ import {
   getAlerts,
   createAlert,
   updateAlertStatus,
+  updateAlertThresholds,
   deleteAlert,
 } from "../../api/alerts";
 import {
@@ -39,6 +40,64 @@ export default function Alerts() {
   const [sendingDigest, setSendingDigest] = useState(false);
   const [hasExistingConfig, setHasExistingConfig] = useState(false);
 
+  const [openAccordions, setOpenAccordions] = useState({});
+  const [thresholdEdits, setThresholdEdits] = useState({});
+
+  function toggleAccordion(alertId) {
+    setOpenAccordions((prev) => ({ ...prev, [alertId]: !prev[alertId] }));
+  }
+
+  function getThresholdEdit(alert) {
+    if (thresholdEdits[alert.id]) return thresholdEdits[alert.id];
+    return {
+      minimum: alert.minimum != null ? String(alert.minimum) : "",
+      maximum: alert.maximum != null ? String(alert.maximum) : "",
+    };
+  }
+
+  function setThresholdEdit(alertId, field, value) {
+    setThresholdEdits((prev) => {
+      const current = prev[alertId] || getThresholdEditForAlert(alertId);
+      return { ...prev, [alertId]: { ...current, [field]: value } };
+    });
+  }
+
+  function getThresholdEditForAlert(alertId) {
+    const alert = alerts.find((a) => a.id === alertId);
+    return {
+      minimum: alert?.minimum != null ? String(alert.minimum) : "",
+      maximum: alert?.maximum != null ? String(alert.maximum) : "",
+    };
+  }
+
+  async function handleSaveThresholds(alertId) {
+    const edit = thresholdEdits[alertId];
+    if (!edit) return;
+
+    const min = edit.minimum.trim() === "" ? null : Number(edit.minimum);
+    const max = edit.maximum.trim() === "" ? null : Number(edit.maximum);
+
+    if (min !== null && isNaN(min)) return;
+    if (max !== null && isNaN(max)) return;
+    if (min !== null && max !== null && min > max) return;
+
+    try {
+      const updated = await updateAlertThresholds(alertId, min, max);
+      setAlerts((prev) =>
+        prev.map((a) => (a.id === alertId ? updated : a)),
+      );
+      setThresholdEdits((prev) => {
+        const next = { ...prev };
+        delete next[alertId];
+        return next;
+      });
+      setError(null);
+    } catch (err) {
+      setError(err.message);
+      console.error("Failed to update thresholds:", err);
+    }
+  }
+
   useEffect(() => {
     async function fetchData() {
       try {
@@ -314,7 +373,14 @@ export default function Alerts() {
                   </p>
                 ) : (
                   <ul className="list-unstyled">
-                    {alerts.map((alert) => (
+                    {alerts.map((alert) => {
+                      const hasAccordion =
+                        alert.type === "incoming_tx" ||
+                        alert.type === "outgoing_tx";
+                      const isOpen = !!openAccordions[alert.id];
+                      const edit = getThresholdEdit(alert);
+
+                      return (
                         <li
                           key={alert.id}
                           className={`alerts__rule ${!alert.enabled ? "alerts__rule--disabled" : ""}`}
@@ -329,27 +395,110 @@ export default function Alerts() {
                                   Threshold: {alert.threshold} ETH
                                 </div>
                               )}
+                              {alert.minimum != null && (
+                                <div className="text-sm text-muted">
+                                  Min: {alert.minimum} ETH
+                                </div>
+                              )}
+                              {alert.maximum != null && (
+                                <div className="text-sm text-muted">
+                                  Max: {alert.maximum} ETH
+                                </div>
+                              )}
                               <div className="text-xs text-dimmed">
-                              Status: {alert.enabled ? "Enabled" : "Disabled"}
+                                Status:{" "}
+                                {alert.enabled ? "Enabled" : "Disabled"}
                               </div>
                             </div>
                             <div className="flex flex--center gap-sm">
                               <Button
                                 onClick={() =>
-                                handleToggleAlert(alert.id, alert.enabled)
+                                  handleToggleAlert(
+                                    alert.id,
+                                    alert.enabled,
+                                  )
                                 }
                               >
                                 {alert.enabled ? "Disable" : "Enable"}
                               </Button>
                               <Button
-                              onClick={() => handleDeleteAlert(alert.id)}
+                                onClick={() =>
+                                  handleDeleteAlert(alert.id)
+                                }
                               >
                                 Delete
                               </Button>
                             </div>
                           </div>
+
+                          {hasAccordion && (
+                            <>
+                              <button
+                                type="button"
+                                className="alerts__accordion-toggle"
+                                onClick={() =>
+                                  toggleAccordion(alert.id)
+                                }
+                              >
+                                <span
+                                  className={`alerts__accordion-chevron ${isOpen ? "alerts__accordion-chevron--open" : ""}`}
+                                >
+                                  &#9654;
+                                </span>
+                                Add optional minimum and maximum
+                                threshold values
+                              </button>
+                              <div
+                                className={`alerts__accordion-panel ${isOpen ? "alerts__accordion-panel--open" : ""}`}
+                              >
+                                <div className="alerts__threshold-inputs">
+                                  <Input
+                                    label="Minimum"
+                                    type="number"
+                                    step="0.000001"
+                                    min="0"
+                                    value={edit.minimum}
+                                    onChange={(v) =>
+                                      setThresholdEdit(
+                                        alert.id,
+                                        "minimum",
+                                        v,
+                                      )
+                                    }
+                                    placeholder="No minimum"
+                                  />
+                                  <Input
+                                    label="Maximum"
+                                    type="number"
+                                    step="0.000001"
+                                    min="0"
+                                    value={edit.maximum}
+                                    onChange={(v) =>
+                                      setThresholdEdit(
+                                        alert.id,
+                                        "maximum",
+                                        v,
+                                      )
+                                    }
+                                    placeholder="No maximum"
+                                  />
+                                </div>
+                                <div className="alerts__threshold-actions">
+                                  <Button
+                                    onClick={() =>
+                                      handleSaveThresholds(alert.id)
+                                    }
+                                    className="btn--sm"
+                                  >
+                                    Save
+                                  </Button>
+                                </div>
+                              </div>
+                            </>
+                          )}
                         </li>
-                    ))}
+                      );
+                    })}
                   </ul>
                 )}
               </div>

frontend/src/pages/login/Login.css

@@ -1,19 +1,38 @@
 .login-page {
-  min-height: 100vh;
+  position: relative;
-  background-image: url(/ping.png);
+  width: 100vw;
-  background-size: 67%;
+  height: 100vh;
-  background-position: center;
+  overflow: hidden;
-  background-repeat: no-repeat;
+  background-color: #000000;
+}
+
+.login-bg-video {
+  position: absolute;
+  top: 50%;
+  left: 50%;
+  min-width: 100%;
+  min-height: 100%;
+  width: auto;
+  height: auto;
+  transform: translate(-50%, -50%);
+  object-fit: cover;
+  z-index: 0;
+  filter: grayscale(85%);
+  -webkit-filter: grayscale(85%);
+  opacity: 0.05;
 }
 
 .login-card {
+  position: relative;
+  z-index: 1;
   max-width: 400px;
-  margin: 20px auto;
+  margin: 0 auto;
   padding: 2rem;
   padding-top: 8rem;
   border: 1px solid var(--color-border-light);
   border-radius: var(--radius-xl);
   background-color: rgba(0, 0, 0, 0.75);
+  top: 20px;
 }
 
 .login-heading {
@@ -32,7 +51,6 @@
   padding: 0.75rem;
   font-size: 1.2rem;
   margin-top: 16px;
-  ;
 }
 
 .login-footer {
@@ -55,10 +73,45 @@
   }
 }
 
-.login-form-hidden {
+.login-card-fadein {
   opacity: 0;
+  animation: fadeIn 2s ease-in-out forwards;
+  animation-delay: 3s;
 }
 
-.login-form-visible {
+.login-tagline {
-  animation: fadeIn 2s ease-in-out forwards;
+  position: relative;
+  z-index: 1;
+  max-width: 630px;
+  margin: 5rem auto 0;
+  padding-left: 2rem;
+  font-style: italic;
+  color: #FFFFFF;
+  font-size: 1.5rem;
+  line-height: 1.5;
+  text-align: center;
+}
+
+.login-interactive-fadein {
+  opacity: 0;
+  animation: fadeIn 2s ease-in-out forwards;
+  animation-delay: 6s;
+}
+
+/* ── Login Responsive ────────────────────────────────────── */
+
+@media (max-width: 480px) {
+  .login-card {
+    max-width: 100%;
+    margin: 0 0.75rem;
+    padding: 1.5rem;
+    padding-top: 6rem;
+  }
+
+  .login-tagline {
+    margin-top: 3rem;
+    padding-left: 1rem;
+    padding-right: 1rem;
+    font-size: 1.25rem;
+  }
 }

frontend/src/pages/login/Login.jsx

@@ -5,7 +5,6 @@ import Input from "../../components/Input";
 import "./Login.css";
 
 export default function Login() {
-  const [isVisible, setIsVisible] = useState(false);
   const [email, setEmail] = useState("");
   const [password, setPassword] = useState("");
   const [error, setError] = useState("");
@@ -36,12 +35,22 @@ export default function Login() {
 
   return (
     <div className="login-page">
-      <div className="login-card" onMouseEnter={() => setIsVisible(true)}>
+      <video
+        autoPlay
+        loop
+        muted
+        playsInline
+        className="login-bg-video"
+      >
+        <source src="/koin_exp_2.mp4" type="video/mp4" />
+      </video>
+
+      <div className="login-card login-card-fadein">
         <h1 className="login-heading">
           <span className="login-brand">Koin Ping</span> - Login
         </h1>
 
-        <div className={isVisible ? "login-form-visible" : "login-form-hidden"}>
+        <div className="login-interactive-fadein">
           {error && <div className="alert alert--error">{error}</div>}
 
           <form onSubmit={handleSubmit}>
@@ -78,6 +87,11 @@ export default function Login() {
           </div>
         </div>
       </div>
+
+      <p className="login-tagline login-card-fadein">
+        A lightweight, on-chain monitoring system giving users real-time
+        situational awareness over blockchain addresses.
+      </p>
     </div>
   );
 }

frontend/src/pages/subscribe/Subscribe.css

@@ -236,3 +236,25 @@
   margin: 0;
   font-style: italic;
 }
+
+/* ── Subscribe Responsive ────────────────────────────────── */
+
+@media (max-width: 480px) {
+  .subscribe {
+    padding-top: 1.5rem;
+  }
+
+  .subscribe__card {
+    padding: 1.25rem;
+  }
+
+  .progress-bar__connector {
+    width: 24px;
+  }
+
+  .progress-bar__dot {
+    width: 26px;
+    height: 26px;
+    font-size: 0.75rem;
+  }
+}

frontend/src/pages/subscribe/Subscribe.jsx

@@ -1,11 +1,3 @@
-/**
- * Subscribe / Subscribe Wizard
- *
- * 5-step guided flow: Create Account -> Add Wallet -> Alert Rules -> Notifications -> Done
- * After account creation, user is redirected to Stripe Checkout for payment.
- * On successful payment, they return here at step 2 (Add Wallet).
- */
-
 import { useState, useEffect } from "react";
 import { useNavigate, useSearchParams } from "react-router-dom";
 import { useAuth } from "../../contexts/AuthContext";

frontend/src/pages/user_account/Account.css

@@ -0,0 +1,77 @@
+.account-page h1 {
+  font-size: 2rem;
+  font-weight: 200;
+}
+
+.account__section-title {
+  font-size: 1.4rem;
+  font-weight: 400;
+  margin-bottom: 1.25rem;
+  color: var(--color-text);
+  border-bottom: 1px solid var(--color-border-light);
+  padding-bottom: 0.5rem;
+}
+
+.account__row {
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+  padding: 0.6rem 0;
+  border-bottom: 1px solid var(--color-border-light);
+}
+
+.account__row--last {
+  border-bottom: none;
+}
+
+.account__label {
+  color: var(--color-text-muted);
+  font-size: 1.1rem;
+}
+
+.account__value {
+  color: var(--color-text);
+  font-size: 1.1rem;
+  text-align: right;
+}
+
+.account__uuid {
+  font-size: 0.85rem;
+  color: var(--color-text-dimmed);
+  word-break: break-all;
+  max-width: 60%;
+}
+
+.account__status {
+  font-weight: 600;
+}
+
+.account__status--active {
+  color: var(--color-success-text);
+}
+
+.account__status--canceled {
+  color: var(--color-danger);
+}
+
+.account__status--canceling {
+  color: var(--color-warning);
+}
+
+.account__status--past_due {
+  color: var(--color-error);
+}
+
+.account__portal-section {
+  margin-top: 1.25rem;
+  padding-top: 1rem;
+  border-top: 1px solid var(--color-border-light);
+}
+
+.account__portal-hint {
+  margin-top: 0.5rem;
+}
+
+.account__password-form {
+  max-width: 400px;
+}

frontend/src/pages/user_account/Account.jsx

@@ -0,0 +1,202 @@
+import { useState, useEffect } from "react";
+import { updatePassword } from "firebase/auth";
+import { auth } from "../../firebase/config";
+import { getAccount, createPortalSession } from "../../api/account";
+import "./Account.css";
+
+export default function Account() {
+  const [account, setAccount] = useState(null);
+  const [loading, setLoading] = useState(true);
+  const [error, setError] = useState(null);
+
+  const [newPassword, setNewPassword] = useState("");
+  const [confirmPassword, setConfirmPassword] = useState("");
+  const [passwordMsg, setPasswordMsg] = useState(null);
+  const [passwordErr, setPasswordErr] = useState(null);
+  const [changingPassword, setChangingPassword] = useState(false);
+
+  const [portalLoading, setPortalLoading] = useState(false);
+
+  useEffect(() => {
+    async function fetchAccount() {
+      try {
+        const data = await getAccount();
+        setAccount(data);
+      } catch (err) {
+        setError(err.message);
+      } finally {
+        setLoading(false);
+      }
+    }
+    fetchAccount();
+  }, []);
+
+  async function handlePasswordChange(e) {
+    e.preventDefault();
+    setPasswordMsg(null);
+    setPasswordErr(null);
+
+    if (newPassword.length < 6) {
+      setPasswordErr("Password must be at least 6 characters");
+      return;
+    }
+    if (newPassword !== confirmPassword) {
+      setPasswordErr("Passwords do not match");
+      return;
+    }
+
+    try {
+      setChangingPassword(true);
+      await updatePassword(auth.currentUser, newPassword);
+      setPasswordMsg("Password updated successfully");
+      setNewPassword("");
+      setConfirmPassword("");
+    } catch (err) {
+      setPasswordErr(err.message);
+    } finally {
+      setChangingPassword(false);
+    }
+  }
+
+  async function handleManageSubscription() {
+    try {
+      setPortalLoading(true);
+      const { url } = await createPortalSession();
+      window.location.href = url;
+    } catch (err) {
+      setError(err.message);
+    } finally {
+      setPortalLoading(false);
+    }
+  }
+
+  if (loading) {
+    return <div className="page">Loading...</div>;
+  }
+
+  if (error && !account) {
+    return <div className="page text-error">Error: {error}</div>;
+  }
+
+  const isCanceling = account.cancel_at_period_end;
+  const statusLabel = isCanceling
+    ? "Canceling"
+    : account.subscription_status === "active"
+      ? "Active"
+      : account.subscription_status.charAt(0).toUpperCase() +
+        account.subscription_status.slice(1);
+
+  return (
+    <div className="page account-page">
+      <h1 className="mb-lg">Account</h1>
+
+      {error && <div className="alert alert--error mb-lg">{error}</div>}
+
+      {/* ── Profile Section ──────────────────────── */}
+      <div className="section mb-lg">
+        <h2 className="account__section-title">Profile</h2>
+        <div className="account__row">
+          <span className="account__label">Email</span>
+          <span className="account__value">{account.email}</span>
+        </div>
+        <div className="account__row">
+          <span className="account__label">User Name</span>
+          <span className="account__value">{account.user_name}</span>
+        </div>
+        <div className="account__row account__row--last">
+          <span className="account__label">User ID</span>
+          <span className="account__value text-mono account__uuid">{account.user_id}</span>
+        </div>
+      </div>
+
+      {/* ── Subscription Section ─────────────────── */}
+      <div className="section mb-lg">
+        <h2 className="account__section-title">Subscription</h2>
+        <div className="account__row">
+          <span className="account__label">Plan</span>
+          <span className="account__value">{account.subscription_plan}</span>
+        </div>
+        <div className="account__row">
+          <span className="account__label">Status</span>
+          <span className={`account__value account__status account__status--${isCanceling ? "canceling" : account.subscription_status}`}>
+            {statusLabel}
+          </span>
+        </div>
+        {account.member_since && (
+          <div className="account__row">
+            <span className="account__label">Member Since</span>
+            <span className="account__value">{account.member_since}</span>
+          </div>
+        )}
+        {account.next_billing_date && !isCanceling && (
+          <div className="account__row">
+            <span className="account__label">Next Billing Date</span>
+            <span className="account__value">{account.next_billing_date}</span>
+          </div>
+        )}
+        {isCanceling && account.period_end_date && (
+          <div className="account__row">
+            <span className="account__label">Access Until</span>
+            <span className="account__value">{account.period_end_date}</span>
+          </div>
+        )}
+
+        {isCanceling && (
+          <div className="alert alert--warning mt-md">
+            Your subscription has been canceled and will not renew.
+            You have full access until {account.period_end_date}.
+          </div>
+        )}
+
+        <div className="account__portal-section">
+          <button
+            onClick={handleManageSubscription}
+            disabled={portalLoading}
+            className="btn btn--ghost"
+          >
+            {portalLoading ? "Redirecting..." : "Manage Subscription"}
+          </button>
+          <p className="text-dimmed text-sm account__portal-hint">
+            Cancel subscription, update payment method, or view invoices via Stripe.
+          </p>
+        </div>
+      </div>
+
+      {/* ── Change Password Section ──────────────── */}
+      <div className="section">
+        <h2 className="account__section-title">Change Password</h2>
+
+        {passwordMsg && <div className="alert alert--success mb-md">{passwordMsg}</div>}
+        {passwordErr && <div className="alert alert--error mb-md">{passwordErr}</div>}
+
+        <form onSubmit={handlePasswordChange} className="account__password-form">
+          <div className="form-field">
+            <label className="form-label">New Password</label>
+            <input
+              type="password"
+              className="form-control"
+              value={newPassword}
+              onChange={(e) => setNewPassword(e.target.value)}
+              disabled={changingPassword}
+              required
+            />
+          </div>
+          <div className="form-field form-field--last">
+            <label className="form-label">Confirm Password</label>
+            <input
+              type="password"
+              className="form-control"
+              value={confirmPassword}
+              onChange={(e) => setConfirmPassword(e.target.value)}
+              disabled={changingPassword}
+              required
+            />
+          </div>
+          <button type="submit" disabled={changingPassword} className="btn btn--primary">
+            {changingPassword ? "Updating..." : "Update Password"}
+          </button>
+        </form>
+      </div>
+    </div>
+  );
+}