# REUSE.md — felhom.eu (hub + website + scripts)

> Before writing new code, check here. Canonical helpers, patterns to copy, traps to avoid.
> Maintenance: update in the SAME commit that adds/changes/deprecates a shared helper.
> Entries cite file + symbol. Line numbers are landmarks only — reconfirm before editing.

## 1. Canonical helpers (MUST reuse — do not reinvent)

### Report ingest & API auth (hub/internal/api/)

| Symbol | File | Short signature | Use for | Gotchas |
|---|---|---|---|---|
| `(*Handler).checkAuthCustomer` | hub/internal/api/handler.go (~L94) | `(r) (customerID string, isGlobal, ok bool)` | Bearer auth for controller-facing endpoints (global key OR per-customer key) | Global key → `("", true, true)`: caller must then trust body `customer_id`. Constant-time compare on global key. |
| `(*Handler).checkAuthHost` | hub/internal/api/handler.go (~L119) | `(r) (hostID, customerID string, isGlobal, ok bool)` | Bearer auth for agent-facing endpoints (global OR per-host key) | Sibling of checkAuthCustomer — do NOT mix the two token namespaces. Global key requires the host row to already exist (see handleHostReport). |
| `(*Handler).handleEvent` + `allowedEventTypes` | hub/internal/api/handler.go (~L1115 / ~L1063) | `POST /api/v1/event` | The ONLY controller→hub structured-event ingest | Unknown `event_type` → 400 (add to the map FIRST). Accepted severities: info/warning/error/critical (critical since v0.31.0); anything else coerces to `"info"` — exact-match lowercase (`"Critical"` coerces). Tests: hub/internal/api/event_test.go. |
| `(*Handler).handleHostReport` | hub/internal/api/handler.go (~L464) | `POST /api/v1/host-report` | Agent heartbeat ingest: denorm + guest upsert | Body cap via LimitReader; per-host key enforces `host_id` match (403 on mismatch); `received_at` is the dead-man's-switch. |
| `(*Handler).handleConfigRetrieve` | hub/internal/api/handler.go (~L1484) | `GET /api/v1/config/{id}`, header `X-Retrieval-Password` | Canonical password-gated retrieval endpoint | Constant-time compare vs `cfg.RetrievalPassword`; 404-before-401 ordering. `handleArtifactManifest` mirrors it EXACTLY — keep them in lockstep. |
| `writeJSON` | hub/internal/api/dr.go (~L25) | `(w, code int, v any)` | JSON responses in api package | Only used in dr.go so far; prefer it over ad-hoc byte-writes for new endpoints. |
| `(*mailRateLimiter).allow` | hub/internal/api/mail.go (~L48) | `(key string) bool` | Per-key token-bucket rate limiting | Refill = perMinute/60 per sec, burst = perMinute; in-memory (lost on restart, accepted). `now` is injectable for tests. |

### Alerting / Resend / dispatcher (hub/internal/notify/, monitor/)

| Symbol | File | Short signature | Use for | Gotchas |
|---|---|---|---|---|
| `(*Dispatcher).ProcessEvent` | hub/internal/notify/dispatcher.go (~L67) | `(customerID, eventType, severity, message, detailsJSON, source)` | THE notification pipeline (operator + customer channels, cooldowns, prefs) | Call in a goroutine (handlers do `go d.ProcessEvent(...)`). No Resend key → silent no-op. `eventType=="test"` bypasses prefs/cooldown. |
| `severityNotifies` | hub/internal/notify/dispatcher.go (~L56) | `(severity string) bool` | Deciding whether a severity emails | warning/error/critical notify; info intentionally doesn't; anything else is logged as unrecognized (v0.24.0 fix — do not regress). |
| `FormatOperatorEmail` / `FormatCustomerEmail` | hub/internal/notify/templates.go (~L24 / ~L118) | `(...) (subject, body)` | Operator (English) / customer (Hungarian) email bodies | Customer messages come from the `customerMessages` map — add the Hungarian text when adding an event type. Budapest TZ via package `init()`. |
| `monitor.EventNotifyFunc` | hub/internal/monitor/staleness.go (~L14) | `func(customerID, eventType, severity, message, detailsJSON, source)` | Decoupling checkers from notify; wired to `dispatcher.ProcessEvent` in main | May be nil — always nil-check before calling (all checkers do). |
| `(*Store).LogNotification` | hub/internal/store/store.go (~L433) | `(customerID, eventType, severity, message, status, errorMsg, channel)` | Audit trail of every send attempt (sent/failed, per channel) | Log BOTH success and failure (dispatcher does). |

### App-mail passthrough (hub/internal/mailrelay/)

| Symbol | File | Short signature | Use for | Gotchas |
|---|---|---|---|---|
| `mailrelay.Sender` / `(*ResendSMTP).Send` | hub/internal/mailrelay/relay.go (~L24 / ~L50) | `Send(ctx, raw []byte, mailFrom, rcptTo) error` | Raw-MIME passthrough to Resend SMTP | Deliberately separate from notify's HTTP path — parse-then-API drops inline CID images (spike-proven). Do NOT "unify" them. Delivery verdict lands at DATA-close. |
| `mailrelay.FromDomain` | hub/internal/mailrelay/relay.go (~L130) | `(raw []byte) (string, error)` | From-HEADER domain extraction for allowlisting | Header domain, not envelope — Resend checks the header. |

### Web auth / session / CSRF (hub/internal/web/)

| Symbol | File | Short signature | Use for | Gotchas |
|---|---|---|---|---|
| `(*Server).RequireAuth` | hub/internal/web/server.go (~L359) | `(next http.Handler) http.Handler` | Session-cookie OR Basic-auth gate for all web routes | Empty passwordHash disables auth entirely (dev mode). Browsers → /login redirect; JSON-ish requests → 401. |
| `(*Server).validateCSRF` | hub/internal/web/server.go (~L446) | `(r) bool` | CSRF check — enforced centrally in `web.ServeHTTP` for every non-GET | No session cookie → returns true (Basic-auth path is exempt). New POST routes get CSRF for free; forms MUST embed `csrfField`. |
| `(*Server).csrfField` | hub/internal/web/server.go (~L483) | `(r) template.HTML` | Hidden `_csrf` input for HTML forms | Pass into template data on every form-rendering handler. |
| `(*Server).CleanupSessions` | hub/internal/web/server.go (~L110) | `(ctx)` — goroutine | Expired-session sweeper | Started once from main; 15-min tick. |

### Status tokens & template funcmap (hub/internal/web/)

| Symbol | File | Short signature | Use for | Gotchas |
|---|---|---|---|---|
| funcMap in `web.New` | hub/internal/web/server.go (~L67) | `template.FuncMap{...}` | ALL template helpers (`timeAgo`, `statusColor`, `json`, `hubVersion`…) | Add new template funcs HERE, nowhere else. Tested by hub/internal/web/funcmap_test.go + render_test.go. |
| `timeAgo` | hub/internal/web/server.go (~L603) | `(t time.Time) string` | Human-relative timestamps in UI | — |
| `statusColor` | hub/internal/web/server.go (~L630) | `(status string) string` | Status → design-system-v2 token (nominal/warn/crit/neutral) | Class SUFFIX only, never inline color (D4). Exception-color principle: healthy = blue/neutral. |
| `(*Server).hostStatus` + `hostStatusClass`/`hostStatusLabel` | hub/internal/web/hosts.go (~L16/34/48) | `(lastReport *time.Time) string` | Host liveness badge | Uses the SAME threshold as HostStalenessChecker (down = 2× stale) — never invent a second definition. |
| `parseSQLiteTime` | hub/internal/store/store.go (~L1160) | `(s string) time.Time` | Parsing ANY timestamp read from SQLite | modernc/sqlite returns multiple formats; raw `time.Parse` will intermittently zero out. Always use this. |
| `compareVersions` | hub/internal/web/server.go (~L571) | `(a, b string) int` | X.Y.Z comparisons in web (floor checks, update-available) | Returns 0 on parse error — unparseable compares as "equal" (see §3). |

### Artifact manifest / Day-0 trust root

| Symbol | File | Short signature | Use for | Gotchas |
|---|---|---|---|---|
| `(*Store).GetArtifactManifest` / `SetArtifactManifest` | hub/internal/store/store.go (~L933 / ~L944) | `() ArtifactManifest` / `(m) error` | The DB-backed (hub_settings) Day-0 artifact record | This is the checksum TRUST ROOT the host-bootstrap verifies against — distinct from Gitea, which only stores bytes. |
| `(*Server).handleSetArtifacts` + `resolveArtifactSHA` | hub/internal/web/configs.go (~L644 / ~L680) | `POST /configuration/artifacts` | Operator UI to vouch artifact versions | With a Gitea client the sha is fetched AUTHORITATIVELY (submitted sha ignored); fetch failure refuses the save. Manual sha only in the no-creds fallback. |
| `(*gitea.Client).ListVersions` / `FileSHA256` | hub/internal/gitea/gitea.go (~L47 / ~L72) | `(ctx, pkg) ([]string, error)` / `(ctx, pkg, ver, file)` | Read-only Gitea generic-package metadata | sha comes from package metadata — artifact bytes are never downloaded. Newest-semver-first sort. |
| `(*Server).artifactChoices` | hub/internal/web/server.go (~L155) | `(ctx, pkg, file) []artifactChoice` | Version+sha dropdown data | nil Gitea client / unreachable → nil → UI degrades to manual entry. One bad version drops itself, not the list. |
| `(*Handler).handleArtifactManifest` | hub/internal/api/handler.go (~L1550) | `GET /api/v1/artifacts/{id}` | Serving the vouched set to the bootstrap script | Auth mirrors handleConfigRetrieve exactly. Unset manifest = empty fields, not an error. |
| `normalizeFloorInput` / `normalizeSHA256` | hub/internal/web/configs.go (~L27 / ~L627) | `(raw string) (string, bool)` | Validating operator-typed versions / shas | Empty string is VALID (means "clear"). Reuse for any new version/sha form field. |

### Config generation & secrets hygiene (hub/internal/configgen/)

| Symbol | File | Short signature | Use for | Gotchas |
|---|---|---|---|---|
| `configgen.Generate` | hub/internal/configgen/configgen.go (~L16) | `(templateYAML, cfg) (string, error)` | Producing a customer controller.yaml | Programmatic overrides (customer id/hub url/api_key) ALWAYS win over config_json; fresh session secret per generation. |
| `configgen.RandomHex` | hub/internal/configgen/configgen.go (~L110) | `(n int) (string, error)` | crypto/rand hex tokens (API keys, session secrets) | — |
| `configgen.RandomPassphrase` | hub/internal/configgen/passphrase.go (~L35) | `(wordCount int) (string, error)` | Human-dictatable Hungarian passphrases (retrieval passwords) | ~29K-word embedded list; 5 words ≈ 74 bits. |
| `(*Store).EffectiveMinControllerVersion` | hub/internal/store/store.go (~L960) | `(customerID) string` | Resolving the floor that actually applies (per-customer → global) | "" = no floor (Phase 2 inert). |

### Assets, store misc, scheduling

| Symbol | File | Short signature | Use for | Gotchas |
|---|---|---|---|---|
| `assets.Manager` (`New`, `ServeFile`, `ReSeed`) | hub/internal/assets/assets.go (~L44/190/122) | seed-dir → PVC sync + manifest | Serving app logos/screenshots to controllers | `ServeFile` sanitizes to `filepath.Base` (no traversal). `isAssetFile` enforces the naming convention. |
| `copyFile` | hub/internal/assets/assets.go (~L259) | `(src, dst) error` | THE atomic file write (tmp + rename) in the hub | Copy this shape for any new on-disk write. |
| `fileSHA256` | hub/internal/assets/assets.go (~L244) | `(path) (string, error)` | Streaming sha256 of a file | — |
| `(*Store).SaveEvent` | hub/internal/store/store.go (~L1003) | `(...) (int64, error)` | Persisting ANY event (controller or hub source) | Pair with dispatcher/`onEvent` — saving alone never notifies. |
| `store.GuestID` | hub/internal/store/store.go (~L1268) | `(hostID string, vmid int) string` | Canonical guest primary key | Never hand-concatenate host+vmid. |
| `scheduleDaily` | hub/cmd/hub/main.go (~L449) | `(ctx, name, "HH:MM", fn, logger)` | Daily jobs in Europe/Budapest (prune etc.) | Blocking — run as goroutine. `parseHM` returns 0,0 (midnight) on bad input. |

## 2. Canonical patterns (copy structure from THE named file)

| Pattern | Canonical file | Key traits |
|---|---|---|
| Monitor checker | hub/internal/monitor/staleness.go | Seed state on construction WITHOUT emitting events; in-memory `states` map under mutex; periodic `Check()`; `emitTransition` = SaveEvent then nil-checked `onEvent`; cleanup of vanished IDs. HostStaleness/HostDisk/HostLeaf/HostCapability/StorageFill all follow it. |
| API endpoint | hub/internal/api/handler.go `ServeHTTP` (~L139) + any handler | Path switch in ServeHTTP; first line of every handler = checkAuth{Customer,Host}; `io.LimitReader` body cap; typed anonymous payload struct; explicit 4xx strings. |
| Web POST action | hub/internal/web/configs.go `handleSetGlobalFloor` (~L602) | CSRF enforced centrally in web ServeHTTP; validate via `normalize*` helper; POST-redirect-GET with `?flash=` token; log INFO on success. |
| Optional dependency injection | hub/internal/web/server.go `Set*` setters (~L131–148) / api handler `SetDispatcher` etc. | Constructor takes hard deps; optional subsystems wired via `SetX` after construction; nil = graceful degradation (never panic). |
| Seam-injected sender for tests | hub/internal/notify/dispatcher.go `sendEmailFn` (~L33) | Function-field defaulting to the real impl in the constructor; tests overwrite it. Same idea: `mailRateLimiter.now`, `mailrelay.Sender` fake. |
| Website page | website/index.html | UTF-8 **with BOM**; shared `<nav>`/`<footer>` byte-identical across pages (only `class="active"` differs); two-tone H1 = `<h1>…<span>accent</span></h1>`; all styling in website/assets/site.css tokens (`:root`) — zero embedded `<style>`; `?v=N` cache-bust on site.css/icons.svg; umami snippet; no CDN fonts; no emoji (sprite icons.svg instead). |
| Gate script | scripts/site_gates.py | Byte-level mechanical gates (BOM, emoji codepoint ranges, nav/footer diff, analytics, banned tokens, cache-bust); run `python scripts/site_gates.py` after ANY website change; non-zero exit on failure. |
| Fetch-validate-install (shell) | scripts/felhom-host-install.sh `step_agent_install` (~L1108) | `fetch_raw` to mktemp → syntax-check (`bash -n`) → `install -m0755 -o root -g root` → only then activate; guarded-mkfs wrapper installed BEFORE the sudoers that references it (ordering is the safety property). All mutations through `run()` (dry-run aware). |
| Website deploy (manifest) | manifests/webpage.yaml | git-sync sidecar (sparse-checkout `/website/` + `/scripts/`, `--link=current`) + init container waits for first sync; nginx serves `current/website`; push to main = deployed, no image build. |
| Secret handling (manifest) | manifests/hub.yaml (env, ~L142) | Secrets via `secretKeyRef` to OUT-OF-BAND secrets created per documentation/runbooks/secrets.md — never inline stringData (see §3). ERRATA (2026-07-03): only `resend-api` is truly out-of-band today; `gitea-creds` is COMMITTED in manifests/felhom.secret.yaml AND live-consumed by hub.yaml — rotation + de-git is a pending operator task (spike SPIKE-a1 appendix). |
| Hub deploy (GitOps) | manifests/hub.yaml `image:` (~L129) | Pinned explicit tag, bumped in git, deliberate ArgoCD sync (auto-sync OFF). Code push alone deploys nothing. |

## 3. Dangerous lookalikes — do NOT reuse

| Trap | Why it bites | Use instead |
|---|---|---|
| `(*Handler).handleNotify` + `formatNotificationEmail` + `sendResendEmail` (hub/internal/api/handler.go ~L1289/1624/1589) | Legacy pre-dispatcher notification trio: no cooldowns, no operator channel, no allowedEventTypes gate, duplicate Hungarian formatter. Controller path is FROZEN until slice-10 cutover. | `POST /api/v1/event` → `Dispatcher.ProcessEvent` + `notify.Format*Email` |
| Severity `"critical"` POSTed to a PRE-v0.31.0 hub | Fixed in hub v0.31.0 (`handleEvent` now accepts critical). Older hubs coerce `critical` → `"info"`, which never notifies — silent alert loss. Case-variants (`"Critical"`) still coerce on every version. | Against an old hub send `warning`/`error`; otherwise lowercase `critical` is safe |
| `compareVersions` for anything security-ish (hub/internal/web/server.go ~L571) | Returns 0 (equal) on unparseable input — a garbage version passes a floor check. `gitea.compareSemver` behaves differently (lexical fallback). | Validate input with `normalizeFloorInput` first; then compareVersions is safe |
| Inline `stringData` secrets à la manifests/felhom.secret.yaml | Commits real credentials to git (healthchecks superuser pw, umami APP_SECRET/POSTGRES_PASSWORD, gitea-creds admin password still live there). | Out-of-band `kubectl create secret` + `secretKeyRef` (hub.yaml resend-api pattern; runbook documentation/runbooks/secrets.md) |
| `kubectl apply` / `kubectl set image` on manifests/ | ArgoCD app `felhom` reverts drift on next sync; live state lies about git. | Edit manifest in git → push → ArgoCD sync (CLAUDE.md steps 3–5) |
| `:latest` image tag in manifests | Re-push doesn't change the manifest → no redeploy; Synced/Rollback misreport. | Pinned version tag, bumped per deploy |
| grep/regex hunting emoji in website HTML | Windows grep false-negatives multibyte emoji (proven in D0). | `python scripts/site_gates.py` (codepoint-range check) |
| Adding a website page without touching site_gates.py | `PAGES` list (scripts/site_gates.py ~L22) is explicit — an unlisted page is silently ungated (BOM/nav/emoji drift undetected). | Add the filename to `PAGES` in the same commit |

## 4. Seams & interfaces (testing + cross-repo)

| Interface | Defined in | Implemented by | Fakes/tests at |
|---|---|---|---|
| `mailrelay.Sender` | hub/internal/mailrelay/relay.go (~L24) | `ResendSMTP` (prod) | fake sender in hub/internal/api/mail_test.go; hub/internal/mailrelay/relay_test.go |
| `Dispatcher.sendEmailFn` (func seam) | hub/internal/notify/dispatcher.go (~L33) | `(*Dispatcher).sendEmail` (Resend HTTP) | hub/internal/notify/dispatcher_test.go |
| `monitor.EventNotifyFunc` | hub/internal/monitor/staleness.go (~L14) | closure over `Dispatcher.ProcessEvent` (main.go) | hub/internal/monitor tests (captured-events func) |
| `api.ConfigTemplateProvider` | hub/internal/api/handler.go (~L24) | `web.TemplateFetcher` (Gitea-pulled controller.yaml template) | stub providers in api tests |
| `api.LatestVersionProvider` | hub/internal/api/handler.go (~L31) | `web.VersionChecker` (registry poll) | hub/internal/api/config_version_ack_test.go |
| `mailRateLimiter.now` (func seam) | hub/internal/api/mail.go (~L27) | `time.Now` | hub/internal/api/mail_test.go clock injection |
| Cross-repo: controller → hub | `POST /api/v1/report` (frozen) + `POST /api/v1/event` | felhom-controller repo | new event types MUST enter `allowedEventTypes` (hub/internal/api/handler.go ~L1063) or the controller gets 400 |
| Cross-repo: agent → hub | `POST /api/v1/host-report`, `/host-enroll`, jobs/desired-state/escrow routes (handler.go ~L145–189) | felhom-agent repo | hub/internal/api/host_test.go, desired_test.go, escrow_test.go, dr_test.go |
| Cross-repo: Day-0 bootstrap → hub | `GET /api/v1/config/{id}` + `/artifacts/{id}` (X-Retrieval-Password) | scripts/felhom-host-install.sh (fetches + sha256-verifies against the hub-vouched manifest) | hub/internal/api/artifact_test.go |
| Cross-repo: controller ← hub assets | `GET /api/v1/assets/manifest` + `/assets/file/{name}` | felhom-controller pulls app logos/screenshots | assets manifest sha-based change detection |

## 5. Extension points (where new features plug in)

- **New event type**: add to `allowedEventTypes` (hub/internal/api/handler.go ~L1063) **and** `customerMessages` (hub/internal/notify/templates.go) **and** the customer-prefs default list if customer-notifiable. Missing the first = controller POST 400s (the known gotcha).
- **New monitor checker**: copy hub/internal/monitor/staleness.go (§2 pattern); wire in hub/cmd/hub/main.go with an `EventNotifyFunc`; severity must be warning/error/critical to notify.
- **New API route**: switch in `api.ServeHTTP` (handler.go ~L139); auth helper first line.
- **New web page/action**: switch in `web.ServeHTTP` (server.go ~L182) — non-GET gets CSRF automatically; template into hub/internal/web/templates/ (embedded FS, parsed in `web.New`); new helpers into the funcMap (server.go ~L67).
- **New template func**: funcMap in web.New only; add a case to hub/internal/web/funcmap_test.go.
- **New daily job**: `scheduleDaily` in hub/cmd/hub/main.go + add pruning to `pruneAll` if data grows.
- **New site gate**: append to scripts/site_gates.py; new website pages go into its `PAGES` list.
- **New artifact kind (Day-0)**: consts `pkg*`/`file*` (hub/internal/web/server.go ~L27), `ArtifactManifest` fields + settings keys (hub/internal/store/store.go ~L905), `handleSetArtifacts`, `artifactManifestResponse` (handler.go), and the install script's verify step.
- **New host-install step**: `step_*` function in scripts/felhom-host-install.sh using `run()`/`fetch_raw`/`die` helpers; keep dry-run coverage.

## 6. Known duplication (observed — NOT fixed)

- Resend HTTP sender ×2: `(*Handler).sendResendEmail` (hub/internal/api/handler.go ~L1589) ≈ `(*Dispatcher).sendEmail` (hub/internal/notify/dispatcher.go ~L185) — byte-near-identical POST to api.resend.com. Kept because the handler copy serves the frozen legacy /notify path.
- Hungarian customer-email formatter ×2: `formatNotificationEmail` (hub/internal/api/handler.go ~L1624) vs `notify.FormatCustomerEmail` (hub/internal/notify/templates.go ~L118). Legacy vs dispatcher; the legacy one lacks the per-event-type message map.
- Semver compare ×2 with DIFFERENT fallback semantics: `web.compareVersions` (hub/internal/web/server.go ~L571, parse error → 0) vs `gitea.compareSemver` (hub/internal/gitea/gitea.go ~L115, parse error → lexical). Documented as deliberate (import-cycle avoidance) in gitea.go, but the behavior drift is not.
- Checker-family structural repetition: staleness.go vs host_staleness.go, and host_disk.go vs storage_fill.go (band/bandRank/bandLabel vs bandForPercent) — same skeleton re-implemented per domain; treated as the accepted §2 pattern rather than a defect.
- Duration formatting ×2: `monitor.formatDuration` (hub/internal/monitor/staleness.go ~L187) vs `web.timeAgo` (hub/internal/web/server.go ~L603) — different audiences (email vs UI) but overlapping logic.