RustProxy/docs/SETTINGS.md

# Listener and response settings

## Administration appearance preferences

**Settings -> Appearance** contains dashboard-only preferences. They are stored per administrator in the existing `admin_preferences` SQLite document and do not create a proxy configuration revision. The preferences are theme (`dark`/`light`), language (`auto` or a language-pack id), global interface scale (70-125%), timestamp format (`24h`/`12h`), chart style (`default`, `soft`, `technical`, `high_contrast`, `neon`, `monochrome`, `warm` or `cool`), button style (`normal` or `compact`), table/log density (`normal`, `compact`, `ultra`), dashboard density (`normal`, `compact`, `ultra`), Overview card order and Overview card visibility. `auto` language follows the browser language when a matching pack exists and otherwise falls back to the configured default pack.

The scale applies to the complete authenticated administration surface, including navigation, workspace content, dialogs, overlays and the draft dock. Text fields, selects, textareas, checkboxes and radios also receive a small proportional control-size adjustment on top of global zoom so field proportions track the selected scale more visibly. Button style is independent: **Normal** keeps the refreshed control sizing and **Compact** restores the smaller source-style sizing, including generated entity actions and tab buttons inside dialogs. Table/log and dashboard density are additional layout controls and do not change the whole-interface scale. The dashboard editor can hide/show and reorder the telemetry cards at the top of Overview; this changes presentation only, not metric collection. The selected time format is shared by logs, backend/runtime diagnostics, audit/session timestamps, certificate views and configuration-history timestamps. Chart presets change colors, surfaces, grid and line presentation only; they do not change sampled data, and the palette selector exposes the main colors for each preset. Each Appearance subsection has its own reset action, and **Reset appearance** restores all documented Appearance defaults without touching unrelated account preferences. A small local cache is retained only to avoid a theme/scale flash before authentication, while the authenticated SQLite preference remains authoritative.

Unfinished Web Server, Vhost, Redirect and Stream editors remain session-only drafts. Their bottom-right dock uses square corners, can collapse to a single title bar, shows the age of each suspended draft and does not persist draft form values to SQLite.

The Settings page includes a local search field that filters category tabs using translated category labels and page content. Filtering never rebuilds settings forms, so unsaved values remain in the DOM. Category navigation remains sticky on desktop and marks categories containing unsaved forms.

Unfinished Web Server, Vhost, Redirect and Stream forms use a session-only draft dock. Closing a dirty editor minimizes its exact browser state to the bottom-right dock so another editor can be opened independently. The dock follows the square-corner panel styling of the dashboard and intentionally avoids rounded/glass presentation. Drafts are intentionally not written to SQLite because form state can contain credentials or other secrets; they are discarded on logout/session reset.

## Certificate API credentials (0.31.9)

Open **Settings → Certificate API** (`/settings?tab=certificate-api`) to manage external certificate automation credentials. The credential list now has **View settings**, **Edit settings**, **Regenerate token** and **Revoke** actions. The preview shows Key ID, non-secret comment, allowed certificate IDs, reload-only/deploy scope and creation/last-use times. Existing bearer token values cannot be viewed: only hashes are stored.

**Edit settings** loads the current credential into a form with fixed Key ID. You may update its comment, list of 1–32 explicit certificate IDs, and **Also allow deploy** permission. **Save settings** changes only this metadata; the current secret stays valid and is never shown or replaced. Legacy `*` certificate grants must be replaced with explicit IDs before saving an edit.

**Regenerate token** requires confirmation. It generates a new random bearer token, preserves the Key ID/comment/permissions/allowed IDs, immediately invalidates the old token and reveals the new token only once. Copy it into the external automation before closing the page. Regeneration updates the token's creation/rotation timestamp and clears last-used metadata. The same existing session + Origin + CSRF checks protect both operations; bearer-only external clients cannot read or change credentials.

The existing **Generate / rotate token** form still creates new Key IDs (and retains its previous ability to rotate a Key ID by supplying it). Use **Edit settings** to modify settings without rotating, and **Regenerate token** to rotate without changing any settings. See [API](API.md) and [access control](API_ACCESS.md).

## Refresh preferences (0.31.0)

**Settings -> Appearance -> Data refresh** saves an additional `refresh` object in the existing `admin_preferences` document for the signed-in account. It does not modify proxy configuration or create any migration. Older documents, including partially populated `refresh` objects, use defaults. Browser and server enforce exact allowed values:

| Preference | Default | Allowed seconds |
|---|---:|---|
| `refresh.live_enabled` | `true` | `true`, `false` |
| `refresh.overview_seconds` | 2 | 1, 2, 5, 10 |
| `refresh.traffic_seconds` | 5 | 0, 3, 5, 10, 30 |
| `refresh.cache_seconds` | 5 | 0, 3, 5, 10, 30 |
| `refresh.system_info_seconds` | 60 | 0, 15, 30, 60, 300 |

`live_enabled=false` disables automatic SSE **and all polling**, including system information. `0` disables only that source's automatic polling. Overview and System information have **Refresh now** buttons; Traffic and Cache retain their own buttons, filters, charts and pagination. The per-view Auto checkboxes for Traffic/Cache/Transform and the Docker live switch remain independent opt-outs, and none changes another administrator's preferences. **Reset section** restores refresh defaults without changing theme or unrelated preferences.

The main `/api/events?interval=N` connection (allowlisted 1/2/5/10, default 2 seconds) carries compact live status plus the existing bounded log snapshot. The server checks the session on every event and retains its heartbeat, viewer cap and normal disconnect cleanup. On an SSE error the browser polls `/api/status?view=live` and `/api/logs` until snapshots resume, not concurrently during healthy streaming. The old full `/api/status` response is kept for API clients and initial diagnostics. The separate authenticated `/api/system-info` reuses cached diagnostics and ACME metadata, never runs diagnostic subprocesses per request, and is fetched automatically only for Overview or the relevant Settings pages. A hidden browser tab pauses the channel and all automatic polling; returning revalidates its session before normal operation. All interval changes take effect immediately, without reloading or changing any server-global cadence.

## System information (0.30.1)

**Settings -> System information** (`/settings?tab=system-info`) is a read-only view of the authenticated `/api/system-info` endpoint (and the initial, backwards-compatible full `/api/status` response). It reports the OS name/kernel on Linux when available, executable architecture, logical CPU count, CPU and RAM telemetry, host/process uptime, RustProxy version, process RSS, thread and file-descriptor counts, and the existing statistics source and data/database locations. Values not supported by the host/platform display as unavailable, never as zero.

ACME diagnostics formerly shown in About and under Administration are now on this tab: mode/state, certificate environment path, and the active Python/pip/Certbot versions. Versions are probed by the ACME runtime setup with bounded subprocess output/timeouts and published from stored runtime status. They are not queried at every page refresh or status API request. Failed/unavailable probes leave the version empty. No new persistent settings or permissions are introduced.

## Rules and headers (0.31.7)

**Settings -> Rules & headers** (`/settings?tab=policies`) now groups the existing **Global User-Agent blocklist**, **Global custom headers** and **Client response** forms as persistent sub-tabs, following the Cache settings layout. There is no migration: each form continues to update its previous configuration section. **Settings -> Security** retains administrative hostname, Origin, session and password policies.

**Vhosts -> Security -> Traffic policy** also supports optional `rate_limit.user_agent_limits` in each vhost, for example:

```json
{
  "rate_limit": {
    "enabled": true, "requests": 120, "window_seconds": 60, "burst": 30,
    "user_agent_limits": [
      {"pattern": "*scanner*", "requests": 10, "window_seconds": 60, "burst": 0},
      {"pattern": "BadBot", "requests": 2, "window_seconds": 60, "burst": 0}
    ]
  }
}
```

The first case-insensitive match wins. A plain pattern searches for a substring and `*` matches any sequence. A matching User-Agent uses its **own bucket for the vhost, rule and client IP** and overrides that request's standard/country throttle; nonmatching requests continue using existing rate rules. Rules also work with `enabled=false` for the base limiter. The User-Agent header is untrusted, so avoid treating these limits as authentication or identity enforcement.

The **Revision history** detail shows only changed leaf fields, scrolling locally when there are many. **Full JSON comparison** is directly below Restore in the action group and opens a separate standard dialog. ACL profile *Attached to* details are collapsed by default. Listener HTTP/2 and HTTP/3 controls have additional spacing.

## Configuration and update semantics

GET `/api/config` returns a revisioned envelope. PUT the entire document with
`expected_revision`. Defaults apply when fields are omitted. Unknown fields are
rejected; failed validation/persistence leaves the old snapshot active. Existing
backend/route/TLS/ACL data must be retained when changing settings. The panel does
this and preserves dirty settings forms across status/language refreshes.

```json
{
  "listeners": {
    "endpoints": [
      {"id":"http", "name":"HTTP", "scope":"public", "enabled":true,
       "binding":{"address":"0.0.0.0:80", "tls":false, "http2":false, "http3":null}},
      {"id":"https", "name":"HTTPS", "scope":"public", "enabled":true,
       "binding":{"address":"0.0.0.0:443", "tls":true, "http2":true,
                  "http2_settings":{"idle_timeout_seconds":300, "max_connection_lifetime_seconds":0, "drain_timeout_seconds":10}}}
    ]
  },
  "server_header": {"mode":"custom", "value":"RustProxy"},
  "compression": {"gzip":true, "br":true, "zstd":true, "deflate":false, "min_bytes":1024},
  "headers": {
    "request": [{"op":"set", "name":"x-proxy-name", "value":"RustProxy"}],
    "response": [
      {"op":"remove", "name":"x-powered-by"},
      {"op":"set", "name":"x-served-by", "value":"RustProxy"}
    ]
  }
}
```

This is a settings fragment, not a replacement for the existing routing/vhost document.
A complete opt-in example is in `examples/cache-dashboard.json`.

The dashboard exposes the complete raw JSON editor under **Settings -> Manual config**.
The same card exposes **Revision history**, which reads the newest 512 retained configuration revisions from the configuration-history table introduced in SQLite schema 8 (current database schema 9) and groups them by month/day. Selecting a revision shows timestamp, actor and only the changed fields against the previous retained revision; the separate Full JSON comparison dialog contains complete JSON documents. An older retained revision can be restored from the same dialog; RustProxy validates it through the normal configuration update path and saves it as a new revision, preserving the prior history.
The historical `/configuration` browser route is retained only as a compatibility alias and
opens that Settings block; it is no longer a primary-navigation item. Prefer the structured
section editors for routine changes so unrelated sections are not republished.

## GeoIP updates

**Settings -> GeoIP updates** controls the background country-database refresh and is enabled by default. The worker starts only after all server sockets have bound successfully, attempts the first refresh immediately, and then refreshes every 24 hours by default. Sources are direct HTTPS file URLs rather than coupled release/checksum base URLs. Publisher SHA-256 verification is optional per file; every downloaded payload is still size-bounded, streamed to a private staging file and parsed as the selected database format before publication.

Two formats are supported. **CSV ranges** uses separate IPv4 and IPv6 files and defaults to the direct `sapics/ip-location-db` `user-country-ipv4.csv` and `user-country-ipv6.csv` assets. **MaxMind DB (MMDB)** uses one `country.mmdb` file for both address families and defaults to the combined sapics `user-country.mmdb` asset. Standard MaxMind country databases are read from `country.iso_code`, then `registered_country.iso_code`; custom country MMDBs may expose top-level `country_code` or a root two-letter country string. To manage a private MMDB outside the updater, place it at `<data-dir>/geoip/country.mmdb`, select MMDB, disable automatic updates and leave the MMDB source URL empty; **Download now** then validates/reloads the local file instead of fetching it.

When a checksum URL is empty, RustProxy deliberately skips publisher-checksum comparison. It still computes a local SHA-256 for the validated download and compares it with the installed file, so unchanged content is not republished or hot-reloaded. This avoids coupling a moving `latest` data URL to a separately moving checksum release. If a checksum URL is supplied, a mismatch rejects the staged file. The configured maximum is 1 MiB..256 MiB and the interval is 60 seconds..31 days. Failures are warnings only; proxy traffic continues and the worker retries. Manual UI refresh, the background worker and managed upgrades share `.geoip-update.lock`. After publication the `ArcSwap` database is replaced atomically: requests already holding a snapshot may finish on it, while subsequent country ACL/rate-limit/logging lookups and status/metrics reads use the new database without a restart.

```json
{
  "geoip_updates": {
    "enabled": true,
    "format": "csv_pair",
    "ipv4_url": "https://github.com/sapics/ip-location-db/releases/download/latest/user-country-ipv4.csv",
    "ipv6_url": "https://github.com/sapics/ip-location-db/releases/download/latest/user-country-ipv6.csv",
    "mmdb_url": "https://github.com/sapics/ip-location-db/releases/download/latest/user-country.mmdb",
    "ipv4_checksum_url": null,
    "ipv6_checksum_url": null,
    "mmdb_checksum_url": null,
    "max_bytes": 268435456,
    "interval_seconds": 86400
  }
}
```

## Administration HTTPS

`administration` is separate from public proxy listeners. It defaults to the startup
loopback address and plain HTTP. Persisted address/certificate changes are validated
immediately but take effect after process restart. A non-loopback persisted bind is
accepted only when `administration.tls` is true. Plain remote HTTP remains available only when process startup explicitly allows it with
`--allow-remote-admin`.

```json
{
  "administration": {
    "listen": "0.0.0.0:9090",
    "tls": true,
    "certificate_id": "admin-example",
    "allowed_hosts": ["admin.example.com"],
    "public_origin": null,
    "session_days": 30,
    "panel_compression": {"zstd": true, "br": true, "gzip": true}
  }
}
```

### Fixed public origin for a reverse-proxied panel (0.31.4)

For a **panel** reached through a trusted reverse proxy, set the optional
`administration.public_origin` in **Settings → Administration** to the exact
browser-facing HTTPS origin (for example `https://panel.example.test`).
**Do not duplicate that hostname in `administration.allowed_hosts`.** Its DNS
hostname is implicitly included in the runtime panel Host allowlist. **Restart
RustProxy**; this is a restart-bound access-control setting. Omit it (`null`) for
direct administration or when forwarded headers are canonical. This setting
is not a wildcard, does not accept HTTP or a URL path, and requires a DNS
hostname rather than an IP address. SQLite schema 9 remains unchanged.

The advanced **Additional allowed DNS hostnames** field controls independent,
extra hostnames only. Older configurations containing both values are
accepted; on editing/saving the redundant duplicate is omitted from the
persisted list. If `public_origin` changes or is cleared, its old hostname is
no longer implicitly allowed (unless explicitly retained as an additional host).

Example for the default **private loopback** administration listener behind an
HTTPS-terminating proxy:

```json
{
  "administration": {
    "allowed_hosts": [],
    "public_origin": "https://panel.example.test"
  }
}
```

The last hop must connect from loopback or an existing explicitly trusted proxy
CIDR. If it is not loopback, configure **only the actual proxy peer CIDR** under
Forwarding → Trusted proxies; be aware the general trusted-proxy setting also
applies to public traffic and must never include untrusted clients. The
administration listener should not be reachable directly from external clients.
Do **not** grant trust to public networks to work around Origin failures.

The pinned URL, not an element of `X-Forwarded-Proto`, defines the panel
scheme/authority. A trusted, bounded proxy chain `https, http` (HTTPS on the
browser side, HTTP on an internal hop) is permitted in this explicit mode.
An `http` first hop, malformed/too-long protocol chain, duplicate/conflicting
`X-Forwarded-Host`, different `Origin`, `Sec-Fetch-Site: cross-site`, and missing
CSRF protection for state-changing requests still result in HTTP 403. The
public proxy/vhost data plane is **not changed**, except that an already opted-in
self-admin vhost can recognize the pinned hostname for its reserved panel session
cookie; other upstreams continue to strip it. Credential-bearing certificate
automation retains its original TLS/forwarding checks.

Prefer fixing the proxy's forwarding headers rather than configuring the pin
when practical. For a TLS-only public entry, the closest trusted hop should
**replace**, not append, forwarded headers using known values, for example:

```nginx
proxy_set_header Host panel.example.test;
proxy_set_header X-Forwarded-Host panel.example.test;
proxy_set_header X-Forwarded-Proto https;
```

Only use that `https` setting on an entry that actually verifies external TLS;
never trust an arbitrary inbound `X-Forwarded-Proto`. If multiple intermediate
proxy hops must append protocol values, the pinned mode provides an explicit
server-side comparison target without accepting a client-supplied origin as
authoritative. Confirm deployment using a real mobile browser and the safe
`administration origin rejected` logs before production rollout.

**Administration → Panel content compression** (next to the admin listener/TLS settings)
controls Zstd, Brotli and gzip for the authenticated HTML document, JavaScript,
CSS and language bundles. Each browser request is negotiated using
`Accept-Encoding` quality values: the highest positive `q` wins, and ties
prefer **Zstd → Brotli → gzip**. Codecs can be enabled independently; the
identity representation is returned when none is acceptable or all are off.
The source is encoded only once per embedded asset and shared across visitors.
Settings persist in the existing revisioned administration document, without
additional CLI flags or a separate environment/config variable, and take effect
without restart. Each compressed response includes `Content-Encoding`,
`Vary: Accept-Encoding` and the representation-specific `Content-Length`.
The response compression of proxied websites remains independent; API responses,
SSE and WebSocket streams are not affected.

**Reverse proxy:** an upstream may remove or replace `Accept-Encoding`. RustProxy
negotiates from the header it actually receives, not the original browser request.
A reverse proxy normally passes through already encoded responses instead of
recompressing them; if the reverse should exclusively manage encoding, configure
it to strip `Accept-Encoding` on requests upstream, or turn the panel codecs off.
This provides compatible HTTP negotiation but does not guarantee identical
compression with every reverse proxy configuration.

`certificate_id: null` uses `data/certs/default.pem` and `default.key`, generated by
the application. A selected inventory certificate is loaded from the same private
certificate directory. `session_days` controls the absolute browser-session lifetime
and must be 7..30 (default 30). It applies without restart; changing listener/TLS/certificate
settings still requires restart. Session cookies are HttpOnly/SameSite=Strict and receive
the `Secure` attribute on HTTPS. When HTTPS is enabled, accidental plain HTTP received on the same administration
port receives a permanent redirect to the same authority/path over `https://`; the
plaintext path contains no administration handlers. An empty `allowed_hosts` accepts
valid DNS Host values on the configured HTTPS port as well as valid numeric destination
addresses. Once `allowed_hosts` contains entries it becomes a strict DNS allowlist for
browser-facing DNS authorities. An explicitly listed hostname may arrive from a trusted
reverse proxy on an external port such as 443 even when the private admin socket is 9090.
Direct IP/`localhost` access is still accepted only on the actual configured admin port.
For HTTPS termination in front of a plain local admin socket, the trusted proxy must pass
its external Host and scheme; `X-Forwarded-Host` is accepted only from loopback/configured
trusted proxy peers and `X-Forwarded-Proto` additionally follows the forwarded-proto trust
policy. Origin/CSRF comparison and the session cookie Secure flag use that external origin.
Use a firewall and normal network policy even with HTTPS.

## Structured access logging

The **Settings -> Logging** page is split into **Outputs**, **JSON format** and **Error log** subsections, using the same in-card sub-tab layout and keyboard interaction as Cache. Outputs controls optional external access-log sinks while the existing bounded live ring remains available to the panel. Sink I/O is performed by a bounded background queue; request processing only performs a non-blocking enqueue. Supported destinations:

- JSONL file append, either one combined file such as `/var/log/rustproxy/access.jsonl` or
  one file per resolved vhost under a configurable directory (default `/var/log/rustproxy/vhosts`).
  Unmatched traffic uses `_unmatched.jsonl`. The managed systemd service provisions
  `/var/log/rustproxy` for the service account and keeps that directory writable under
  `ProtectSystem=strict`. Other custom paths still need matching service permissions.
- Logstash TCP using `host:port` (IP or DNS). Each event is one JSON line.
- Loki HTTP(S) push. Optional bearer credentials are read from an environment variable
  named by `bearer_token_env`; the secret itself is not stored in configuration.

`logging.format.fields` maps output field names to standard event fields; an empty map
emits the complete standard event. The panel provides Standard, Nginx-style, ECS-style
and Minimal presets plus a visual field selector/renamer with JSON preview. Advanced raw
mapping remains available for aliases not representable by the simple builder. Supported mapped sources include `vhost`, `route`, `cache_effective_enabled`, `transform_effective_enabled`, `backend`, request/response metadata and cache outcome fields. `static_fields` adds constant string fields. For low-level `protocol_error` events, RustProxy always preserves the required diagnostic envelope (`event`, error kind/detail, time, client/local/TLS/protocol fields, status and outcome) even with a custom mapping, so malformed-traffic records remain searchable in the built-in Logs explorer. Loki labels are separately configurable.
`/api/status.logging.sinks` reports queue capacity, dropped events, successfully delivered
events and sink errors.

## Hot and cold cache tiers

`cache.max_bytes` and `cache.max_entries` bound the HOT RAM tier. `max_bytes` is charged from retained body backing allocation plus entry metadata rather than only payload length. `cache.transient_max_bytes` separately bounds in-progress fills and full bodies moving between HOT and COLD; `cache.cold_queue_max_bytes` additionally caps queued demotions in bytes, and `cache.hot_eviction_max_objects` bounds one LRU admission attempt. The source defaults are 256 MiB HOT, 16 MiB maximum object, 64 MiB transient and 32 MiB COLD queue. The Settings panel calculates conservative/recommended/performance presets from the lower of host RAM and a finite cgroup memory limit without changing the COLD disk budget. It also warns when HOT + transient is a large fraction of effective RAM, when the additional configured cache budget is large compared with current host/cgroup headroom, when the COLD queue exceeds transient RAM, or when the object ceiling cannot fit in transient RAM. Automatic presets are disabled below 256 MiB effective RAM. On a 2 GiB effective-memory VM the recommended profile selects approximately 400 MiB HOT, 96 MiB transient, 16 MiB maximum object, 48 MiB COLD queue, 6400 HOT entries and a 64-object LRU admission limit. The optional persistent
cold tier is controlled by `cold_enabled`, `cold_path`, `cold_max_bytes`,
`cold_max_entries`, `cold_gc_interval_seconds`, `cold_gc_max_delete`,
`cold_after_seconds`, `cold_on_lru`, `cold_on_idle` and `cold_on_shutdown`.
`cold_gc_interval_seconds` defaults to 60 and `cold_gc_max_delete` to 256. Pressure GC
starts at roughly 90% of the configured byte/entry budget and cleans toward roughly 80%
without deleting more than the configured per-pass cap. `cold_path` is relative to the RustProxy data directory and cannot
contain parent traversal or an absolute path. The two demotion switches independently
select LRU-pressure and idle objects; shutdown flush is a best-effort direct write during
a graceful restart. Demotions use a small bounded queue and release hot accounting before
disk persistence so cold storage does not retain an unnecessary second body buffer in RAM.
Cold metadata is readable JSON and bodies are raw `.body` files; reads are size/SHA-256
checked before promotion to RAM. Since 0.21.0 objects are sharded by the first two SHA-256
hex characters (`cache/cold/00/...` through `ff/...`), with shard directories created on
first write. The previous flat Cold Cache is intentionally not migrated. Purge operations
clear both in-memory indexes and schedule disk cleanup; selective cleanup uses the same
GC/eviction path and runs asynchronously.

Version 0.22 adds foreground fill collapsing (`collapse_enabled`,
`collapse_wait_timeout_ms`, `collapse_timeout_fallback`), detailed stale-if-error policy
(`stale_if_error_timeout`, `stale_if_error_connection`, `stale_if_error_dns`,
`stale_if_error_tls`, `stale_if_error_statuses`) and opt-in proactive refresh
(`proactive_refresh_enabled`, `proactive_refresh_before_expiry_seconds`,
`proactive_refresh_percent`, `proactive_refresh_max_inflight`). Defaults preserve the
previous stale-if-error behavior; proactive refresh is disabled by default. Selective
PURGE/BAN is available in the authenticated API/panel, and HTTP BAN/PURGE has an optional, separately stored CIDR allowlist (`cache.http_invalidation_allowed_cidrs`, empty by default). See
[CACHE.md](CACHE.md) for request-collapse, Range and invalidation semantics.
The adjacent **info (`i`) popover** in Settings → Cache shows ready-to-copy
`curl -X PURGE` and `curl -X BAN` examples in English and Polish, including
the explicit `BAN /` confirmation. These public methods authorize by the
source IP/CIDR only; they do not accept a browser admin session as a bypass.
See [0.31.0 security audit](SECURITY_AUDIT_0.31.0.md) for reverse-proxy trust and tests.

## Static-response transformation

`transform` is a formal identity-response stage between the upstream response and shared
cache storage. `transform.enabled` is the global kill switch, but every vhost must also
set its own `transform.enabled=true`; vhosts stay disabled by default even when the global
engine is enabled. Global defaults enable JavaScript and CSS transformation and leave
HTML, SVG and JSON off. `extensions` controls extension-based detection and
`max_body_bytes` (1 KiB..32 MiB, 2 MiB default) bounds aggregation/decoding.

The pipeline is `origin -> decode supported Content-Encoding -> transform -> cache
identity representation -> client compression`. JavaScript/CSS can be enabled normally;
HTML minification, SVG optimization and JSON compaction are independent optional formats.
Recognition uses safe configured extensions and known Content-Type values. Binary/image
formats outside those explicit transform types are not transformed.

Origin `Cache-Control: no-transform` always disables transformation. When bytes change,
RustProxy removes representation-specific length/digest/encoding metadata and creates a
new strong `rustproxy-*` ETag for the transformed representation. The original origin
ETag/Last-Modified are kept separately and used for origin revalidation, so a proxy ETag
is never sent upstream as though it validated the original object. The transformed
identity body is what enters cache, preventing repeated minification on every HIT.

## Global TLS protocol and cipher policy

`tls.policy` is the global baseline inherited by every TLS host. It controls TLS 1.2,
TLS 1.3 and optional rustls cipher-suite names. An empty `cipher_suites` list uses the
ring provider defaults. Settings shows both the currently effective cipher suites and
the complete selectable suite inventory. At least one protocol version and
one compatible effective suite are required. This policy is also used by administration
HTTPS. HTTP/3 requires TLS 1.3 and a TLS 1.3 suite. Vhosts can narrow TCP TLS with
`tls_policy`; when a vhost has HTTP/3 enabled on a selected H3-capable listener it must
match the global policy because QUIC TLS is shared per UDP listener. Available suite names are exposed in authenticated status for
the Settings editor.

## Listeners: saved intent, not hot rebinding

When an HTTP, HTTPS or administration address was explicitly supplied by systemd/CLI
(or the corresponding service environment variable), that exact startup bind is a
process contract: the panel shows it as locked and configuration updates cannot remove,
disable or change it. If an address was not explicitly supplied at startup, listener
entries remain freely addable/removable/editable subject to normal validation.

`listeners.endpoints` is the only persisted frontend socket configuration. Each
endpoint has a stable id/name, an informational scope label, an enabled flag and one
primary binding containing IP:port, TLS, HTTP/2 plus its optional lifecycle settings, and optional HTTP/3 settings. Optional
`additional_addresses` reuse that same transport policy on up to 15 further addresses.
When more than one address is configured every address must be explicit; `0.0.0.0` and
`::` are rejected so a multi-IP selection cannot silently mean every interface. IP/port
and transport capability belong here, not inside a vhost. IPv6 uses `[address]:port`.

A vhost references endpoints through `frontend.listener_ids`. Listener changes are
restart-required because they alter TCP/UDP sockets or TLS ALPN capability. The
listener editor owns the HTTP/2/H2C and HTTP/3 enable/disable switches. An H2/H2C row
links to **HTTP connections -> HTTP/2** for idle, absolute-lifetime and graceful-drain
limits; an enabled H3 row links to **HTTP connections -> HTTP/3** for advertisement,
connection, stream and idle-timeout limits. Both tuning pages are listener-scoped and
do not own protocol enablement. Vhost H2/H3 switches only narrow the protocols already
enabled by the selected endpoints; they never create a protocol that Settings disabled.

The administration listener is independent and cannot share a frontend port.
Bindings must be valid local unicast/wildcard addresses; conflicting overlapping
endpoints are rejected rather than silently widened.

## Server and other client headers

`server_header.mode` is `preserve`, `hide`, or `custom`. Fresh installations default to `custom` with the exact value `RustProxy`; existing saved installations retain their configured policy. Custom values are
nonempty, bounded to 256 bytes and validated against header injection. Preserve
means retain the result of origin/global/route rules; it does not add a missing
header. Hide/custom take final precedence, including proxy-generated errors.

Global and route `headers.response` apply to client responses; `headers.request`
apply only upstream. Each scope/direction supports up to 32 ordered set/append/remove
rules. Remove has no value. Global rules precede route rules. Multiple Set-Cookie
values remain distinct. Admin-session cookie names are never forwarded or set by
public proxy rules. Transport, framing and trusted forwarding/identity fields are
protected. Cache diagnostic fields are owned by the cache controls, not generic rules.

Global response rules also cover generated errors; route-specific rules apply only
after an origin route response exists. Client policy changes use hot configuration
publication and invalidate the RAM cache. In-flight exchanges retain their old
snapshot; no mixed-version configuration is applied midway through a response.

## Compression

`zstd`, Brotli and gzip default ON; deflate defaults OFF. `min_bytes` defaults to 1024
(valid 32..1048576). The streaming middleware keeps its default content-type safety
predicate plus the RustProxy minimum-size predicate. Unknown-length eligible bodies can
be streamed without aggregating the complete response merely to discover its size.

RustProxy parses `Accept-Encoding` quality weights before invoking the encoder. Client
`q` values win. When two or more enabled codecs have equal quality, the deterministic
server preference is `zstd -> br -> gzip -> deflate`. An existing `Content-Encoding` is
always passed through and never recompressed. `no-transform`, request ranges/Content-Range,
SSE, upgrades, HEAD/1xx/204/304 and explicitly skipped internal responses remain excluded.
`Cookie`, `Authorization`, `Set-Cookie`, `Cache-Control: private` and `no-store` do not by
themselves disable compression; cacheability and dynamic compression are separate policies.
Applications that place secrets and attacker-controlled reflection in the same compressed
response can disable compression at the vhost or Web Service scope when their threat model
requires BREACH-style mitigation.

The global Response panel selects available codecs and the minimum size. Each ordinary
vhost and Web Server service may inherit, enable or disable dynamic compression and independently
inherit/enable/disable zstd, Brotli, gzip and deflate. Docker vhosts intentionally expose only one
Compression checkbox: when enabled they use the globally enabled codec set and priority, with no
per-Docker-vhost codec selectors. Global codec switches remain the hard ceiling: a local `true`
override cannot enable a codec disabled in the global Response panel. `min_bytes` remains global.

`Vary: Accept-Encoding` is added when compression is negotiated; content length is removed
for the transformed body. Strong ETags are weakened, and identity-body content digests and
`Accept-Ranges` are removed. Encoders use their fastest preset; there is no panel
compression-quality slider in this release.

## Diagnostics and units

Samples run off the traffic path roughly every two seconds. CPU and network rates
need two successful samples. Host CPU is aggregate; process CPU uses 100% per busy
logical CPU and can exceed 100%. Neither is normalized to a container CPU quota.
Host memory is MemTotal minus MemAvailable. RSS/FDs/threads and process I/O come
from procfs. Network rates sum non-loopback interfaces in the process network
namespace, not just RustProxy traffic. Load average is OS scope, not latency.

The process's cgroup v2 memory files are read at the standard mount location when
available. Linux keeps the existing `/proc`/cgroup metric names, units and behavior.
FreeBSD/OpenBSD/NetBSD use native system interfaces where the same metric is available;
unknown or unsupported values remain null rather than being fabricated. Snapshot timestamps and sample age are shown;
cache counters and proxy request metrics are separate from OS resource metrics.
The dashboard history is browser-local and resets on reload/sign-out. No time-series
database, disk utilization chart or Windows/macOS OS sampler is implemented.

## HTTP/2 compatibility and per-vhost settings

HTTP/2 lifecycle settings are listener-scoped under `listeners.endpoints[].binding.http2_settings`:

- `idle_timeout_seconds` (default 300) retires only a truly unused H2 connection; active streams and current frame I/O postpone it.
- `max_connection_lifetime_seconds` (default 0) is an independent absolute lifetime; `0` disables this limit.
- `drain_timeout_seconds` (default 10) bounds how long accepted streams may finish after retirement begins.

Idle and lifetime retirement both send GOAWAY, stop accepting new streams, drain already accepted streams and then close TCP. RFC 8441 WebSocket/H2 Extended CONNECT streams are counted as active until their response body/tunnel ends. The same settings apply to TLS H2 and cleartext H2C on that named listener.

For backward compatibility, the top-level `http2` object is still accepted as the fallback for an H2/H2C listener that has no explicit `binding.http2_settings`. The structured UI writes explicit per-listener settings; operators should treat the top-level object and `PUT /api/config/http2` as legacy compatibility surfaces rather than the preferred configuration path.

A named TLS listener with `binding.http2: true` advertises H2 capability and always
retains HTTP/1.1 fallback. `binding.http2: false` makes that listener HTTP/1.1-only.
Cleartext H2 uses `binding.h2c: true`. Changing listener transport capability or H2 lifecycle settings requires restart.

A vhost can additionally set `http2_enabled: false`. RustProxy reads TLS ClientHello
and SNI before committing to ALPN, so a vhost that disables H2 gets HTTP/1.1-only
ALPN even while another hostname on the same listener keeps H2. `http3_enabled` is
the equivalent per-vhost H3 opt-out. The panel enables these switches only when a
selected listener provides the protocol. No failed application request is replayed
to downgrade.

Vhosts have their own backend pool, health/keepalive/affinity controls, ACL and
security/custom response headers. See VHOSTS.md. Global Server policy still takes
final precedence. Per-vhost compression can filter individual globally enabled codecs.

The reported `SizeAbove(u16)` compilation error is removed by a custom u64 predicate,
not a cast or panic-producing conversion. Compression thresholds retain the full
32..1048576-byte setting range. Known body length/Content-Length is compared exactly;
unknown streaming lengths are eligible without buffering the full body. Actual
compression execution still requires the compiler-enabled acceptance suite.

## Management in 0.3.0

Settings contains a direct Security shortcut (accounts, sessions and host ACLs)
and a vhost shortcut (SSL, headers, cache and pages). Compact is the default density;
Dense and Comfortable change spacing/control sizes without browser zoom or logo
redesign. The preference is local to the browser, not a global proxy setting.

Global Pages configures error overrides, direct-IP and unknown-host responses.
See MANAGEMENT.md for inheritance, allowed statuses and security implications.
Access logs have moved out of the dashboard into a separate modal/docked window.
Filters stay above the scrollable rows; counts and exports use the same selection.

## Named listeners, forwarding and diagnostics (0.4.0)

As of 0.8.0, the vhost editor no longer asks for a free-form listener IP. Configure
listener IP/port/protocol once in this Settings section, then select named endpoints in
the vhost. The pre-production inline/global listener format is no longer accepted. This separates
socket intent from host routing and avoids duplicating listening IP configuration across
vhosts.

`listeners.endpoints` is the only proxy-listener configuration. Each record has id,
name, scope, enabled and a binding with address, tls, http2, optional http2_settings, h2c and optional http3. Scope
is only a label. A vhost uses `frontend.listener_ids`; every reference must exist.
Conflicting protocols on shared sockets are rejected.
Changes to effective transport plans need restart, including H2 lifecycle and H3 limits. The UI
shows saved named entries and actual bound transports separately.

`forwarding` controls trusted CIDRs and forwarded-proto acceptance.
`diagnostic_headers` exposes only `request_id` (false initially). Vhosts can override the diagnostic
policy and Server policy; absent/null means inherit. Runtime/cache/static/error
responses pass through the same final header policy.

See INTEGRATIONS_040.md and HTTP3.md for complete JSON, limits and security details.


## 0.5.0 changes (override earlier baseline examples)

A named TLS listener with omitted http3 uses default H3 limits. Explicit null is
persisted as disabled. Overlapping named sockets must match protocols AND H3 limits;
the error identifies owners and remedies. A changed binding requires restart, including
UDP protocol/limit changes. Check UDP port availability before upgrading.

The diagnostic control is `request_id` (false by default). The removed hide_mock_origin field is not accepted; use normal response-header removal
for X-Mock-Origin. Existing custom Server values remain unchanged.

Cache decision/object inspection is under Cache, separate from Overview. Basic
manual certificate issuance is under Certificates; TSIG is never a configuration
field. See CACHE_DIAGNOSTICS.md and ACME_RFC2136.md for exact scopes and limits.

## 0.6 navigation and exporter

The Settings page now has eight switching cards: Listeners, Response, Cache,
Headers, Forwarding, Pages, Prometheus and Security. Unsaved values remain in
place while switching; switching alone never writes configuration. Security is
not a separate sidebar item. Use arrow keys/Home/End in the tab bar.

The Prometheus card controls enabled, bind IP/port, URL path, client CIDRs,
bearer-token environment variable name and optional collectors, including the bounded
Traffic analytics collector. Only the variable name is exported; supply the actual secret to the service separately. See
PROMETHEUS.md for immediate revocation, restart rules and scrape configuration.