Merge pull request #1026 from ruvnet/feat/v2-beyond-sota-sweep-m8

Beyond-SOTA sweep M8 (ADR-162): enforce plugin Ed25519 signatures + capability isolation + bounded RunModes

docs/adr/ADR-161-homecore-server-layer-security.md

@@ -196,7 +196,8 @@ fields are **never read** for verification (only ever set to `None` in tests).
 re-doc'd **"(P4 — not yet enforced, ADR-161/B5)"** — parsed and round-tripped,
 but no integrity/signature check happens before a plugin runs. No verification
 code was added (that is P4); the doc now matches the code.
-**Grade: doc-honesty (no behavior change).**
+**Grade: doc-honesty (no behavior change).** *(Superseded by ADR-162 §P4:
+the hash/signature gate is now implemented and enforced.)*
 
 ## Negative Results (NO-ACTION positives — audited, found correct, cited not edited)
 
@@ -213,17 +214,23 @@ touched:
 
 ## Deferred Backlog (Nothing Dropped)
 
-- **Plugin authority-isolation (P5)** — `homecore_permissions` claims are parsed
-  but not enforced at the host-call boundary. **ACCEPTED-FUTURE.**
-- **Plugin signature/hash verification (P4)** — implement the
+- **Plugin authority-isolation (P5)** — ~~`homecore_permissions` claims are parsed
+  but not enforced at the host-call boundary.~~ **DONE — ADR-162 §P5.**
+  `hc_state_set` now consults a `PermissionSet` distilled from the manifest;
+  an undeclared write returns a typed `-3` to the guest.
+- **Plugin signature/hash verification (P4)** — ~~implement the
   `wasm_module_hash`/`wasm_module_sig`/`publisher_key` gate that B5 now honestly
-  says is absent. **ACCEPTED-FUTURE.**
+  says is absent.~~ **DONE — ADR-162 §P4.** `WasmtimeRuntime::load_plugin` now
+  SHA-256-checks the module, Ed25519-verifies the signature against
+  `publisher_key`, and enforces a `PluginPolicy` trust allowlist
+  (secure-default rejects unsigned/untrusted/tampered modules).
 - **HAP real pairing (P2)** — SRP/HKDF pairing + encrypted sessions; current
   bridge is an accessory-mapping surface. **ACCEPTED-FUTURE (honestly stubbed).**
-- **`RunMode::Queued`/`Restart`/`max` ordering** — `Single`/`Parallel` are
+- **`RunMode::Queued`/`Restart`/`max` ordering** — ~~`Single`/`Parallel` are
   honored; bounded queueing, restart-kill, and `max` concurrency are not yet
-  wired (every non-Single mode is parallel). **ACCEPTED-FUTURE** — the
-  `engine.rs` doc states exactly this, no over-claim.
+  wired (every non-Single mode is parallel).~~ **DONE — ADR-162 §A5.** Restart
+  aborts the in-flight task, Queued serializes via a per-automation async mutex,
+  and `max: N` caps concurrency via a per-automation semaphore.
 - **Automation YAML load-at-boot** — the engine starts empty; a YAML loader is
   P-next. The bin log states "0 automations registered" honestly.
 

docs/adr/ADR-162-plugin-security-and-bounded-runmodes.md

@@ -0,0 +1,186 @@
+# ADR-162: HOMECORE Plugin Security (Signature + Capability Isolation) & Bounded Automation RunModes — Making ADR-161's Deferred Claims TRUE
+
+- **Status**: accepted
+- **Date**: 2026-06-12
+- **Deciders**: ruv
+- **Tags**: homecore, homecore-plugins, homecore-automation, plugin-security, wasm-signature-verification, ed25519, capability-isolation, runmode, prove-everything, soundness, honest-labeling
+- **Amends**: ADR-161 (relabelled P4/P5 + §A5 deferrals → now enforced), ADR-128 (plugin manifest), ADR-129 (automation engine)
+
+## Context
+
+Beyond-SOTA sweep **Milestone 8**, scoped to `homecore-plugins` and
+`homecore-automation` only, under the project's **prove-everything /
+anti-"AI-slop"** directive.
+
+ADR-161 (Milestone 7) did the honest thing with three plugin/automation
+items it could not finish in that window: rather than fake them, it **relabelled
+them as deferred** —
+
+- **P4** (plugin signature verification): the manifest's `wasm_module_hash` /
+  `wasm_module_sig` / `publisher_key` were re-doc'd "(P4 — not yet enforced,
+  ADR-161/B5)" — parsed and round-tripped, but **never checked** before a
+  plugin runs.
+- **P5** (plugin authority isolation): `homecore_permissions` claims were
+  parsed but **never consulted**; `hc_state_set` let any plugin write any
+  entity, including `lock.*` / `alarm_control_panel.*`.
+- **§A5** (`RunMode`): `Single`/`Parallel` were honored; `Restart`/`Queued`/
+  `max: N` were honestly documented as still **unbounded-parallel**.
+
+### Headline — the deferred security items are now ENFORCED + TESTED
+
+M8 turns those honest deferrals into real, tested behavior. The plugin trust
+boundary is now sound (a tampered module, an untrusted publisher, or an
+unsigned module is rejected by the secure default), an over-privileged plugin
+write is denied with a typed error, and the bounded run-modes actually bound.
+**Every fix is pinned by a test that FAILS on the pre-M8 code** — each of the
+three RunMode tests was additionally run against a simulated unbounded-parallel
+dispatch and confirmed to panic.
+
+The Ed25519 crypto reuses the in-repo `cog-ha-matter::witness_signing` pattern
+(same `ed25519-dalek` 2.x API, same deterministic-test-key convention). SHA-256
+matches the `sha256:` prefix the manifest already declared and the
+`cog-ha-matter` cog manifest's `binary_sha256` hex convention. No new external
+dependency tree was introduced — `ed25519-dalek` / `sha2` / `hex` / `base64`
+were already in the workspace `Cargo.lock` (cog-ha-matter / bfld pull them in);
+only new dependency *edges* were added to `homecore-plugins`.
+
+Grading vocabulary (ADR-152 / ADR-158 / ADR-160 / ADR-161):
+- **MEASURED** — reproduced in this worktree, command + failing-on-old test recorded.
+- **ACCEPTED-FUTURE** — deliberately deferred, nothing dropped.
+
+## Decision — Fixes Landed
+
+### §P4 — Plugin signature & integrity verification (SECURITY) — MEASURED
+
+`homecore-plugins/src/manifest.rs` declared `wasm_module_hash` /
+`wasm_module_sig` / `publisher_key` but they were **never read** for
+verification; the load path (`wasmtime_runtime.rs`) instantiated any `.wasm`
+bytes handed to it.
+
+**Real fix** (`src/verify.rs`, wired into `WasmtimeRuntime::load_plugin`):
+before instantiation the runtime now —
+
+1. computes the **SHA-256** of the actual `.wasm` bytes and rejects if it ≠ the
+   manifest's `wasm_module_hash` (`sha256:<hex>`) — tamper detection;
+2. verifies the **Ed25519** `wasm_module_sig` (`ed25519:<base64>`, 64-byte raw)
+   over the 32-byte digest against `publisher_key` (`ed25519:<base64>`, 32-byte
+   raw) and rejects on failure;
+3. enforces a configurable **trust policy** — `PluginPolicy::trusted(&[keys])`
+   is an allowlist of publisher verifying keys; `PluginPolicy::AllowUnsigned`
+   is an explicit dev escape hatch that LOGS a loud `warn` on every load it
+   waves through. The **secure default rejects unsigned and unknown-publisher
+   modules.** `PluginPolicy::deny_all()` trusts no publisher.
+
+A typed `PluginError::SignatureRejected` is returned (no host panic). The
+legacy permission-free `load_wasm` is retained for first-party/trusted/test
+modules; production loading goes through `load_plugin`.
+
+**Failing-on-old tests** (`tests/integration.rs`, `--features wasmtime`) — all
+drive `load_plugin`, which **did not exist** on the old code (so the gate is
+genuinely new):
+- `p4_tampered_module_is_rejected` — a byte-flipped `.wasm` → hash mismatch → rejected.
+- `p4_valid_sig_from_trusted_key_loads` — a valid sig from an allowlisted key loads.
+- `p4_valid_sig_from_untrusted_key_is_rejected` — a correctly-signed module from a key NOT on the allowlist is rejected.
+- `p4_unsigned_module_rejected_by_default_loads_only_under_allow_unsigned` — unsigned rejected under `deny_all`, loads (with warn) only under `AllowUnsigned`.
+- Unit (`src/verify.rs`): `valid_sig_from_trusted_key_passes`, `tampered_module_is_rejected`, `valid_sig_from_untrusted_key_is_rejected`, `forged_signature_is_rejected`, `unsigned_module_rejected_under_default_policy`.
+
+A real deterministic keypair signs real `.wasm` bytes in the tests.
+The manifest doc now reads **"(P4 — ENFORCED, ADR-162)"**. **Grade: MEASURED. Milestone headline.**
+
+### §P5 — Plugin authority / capability isolation (SECURITY) — MEASURED
+
+`wasmtime_runtime.rs::hc_state_set` applied any write a plugin requested,
+ignoring the manifest's `homecore_permissions`.
+
+**Real fix** (`src/permissions.rs` + `hc_state_set`): the manifest's
+`homecore_permissions` (the `state:write:<glob>` form, or a bare entity glob
+like `light.*`) are distilled into a `PermissionSet` installed in the plugin's
+Wasmtime store. The `hc_state_set` host import consults
+`permissions.may_write(entity_id)` before applying a write and returns a typed
+`-3` (permission denied) to the guest on a violation — **the host is not
+panicked.** Wasmtime already gives memory isolation; this adds **authority**
+isolation. A plugin with **no** write grants can write nothing (secure default).
+
+**Failing-on-old tests** (`tests/integration.rs`, `--features wasmtime`):
+- `p5_declared_light_plugin_may_write_light_but_not_lock` — a `light.*` plugin writes `light.kitchen` (succeeds) but is REJECTED (`-3`, and the entity is not written) when it tries `lock.front_door`.
+- `p5_plugin_with_no_permissions_can_write_nothing` — a plugin with empty `homecore_permissions` cannot write `light.kitchen`.
+- Unit (`src/permissions.rs`): domain-glob, exact-grant, wildcard, read-grants-don't-confer-write, no-permissions, and explicit `state:write:` form.
+
+The manifest doc now reads **"(P5 — ENFORCED, ADR-162)"**. **Grade: MEASURED.**
+
+### §A5 — Bounded automation RunModes (Restart / Queued / max) — MEASURED
+
+`homecore-automation/src/engine.rs` (per ADR-161) honored `Single`/`Parallel`
+but spawned an unbounded parallel task for `Restart`/`Queued`/`max`.
+
+**Real fix** (`src/runmode.rs`, a per-automation `RunState` the engine owns and
+dispatches through at all three trigger sites — event loop, timer, test hook):
+- **Restart** — aborts the in-flight action task via `tokio::task::AbortHandle`, then starts a fresh one.
+- **Queued** — serializes runs in arrival order via a per-automation async `Mutex`: sequential, never concurrent, nothing dropped.
+- **max: N** — caps concurrency at N via a per-automation `Semaphore`; triggers beyond N **queue** (await a permit) rather than running concurrently. (HA bounded `parallel`/`queued` semantics — chosen and documented as *queue beyond N*, not drop.)
+- `Single`/`IgnoreFirst` re-entrancy guard and `Parallel` preserved.
+
+`engine.rs` trimmed to **433 lines**; the run-mode machinery lives in the new
+`runmode.rs` (153 lines) to keep both under the 500-line guideline.
+
+**Failing-on-old tests** (`tests/engine_behaviors.rs`) — each was run against a
+simulated unbounded-parallel dispatch and confirmed to panic:
+- `restart_mode_cancels_prior_run` — prior run is aborted: exactly **1** completion (old: both ran → 2).
+- `queued_mode_runs_sequentially_not_concurrently` — 3 rapid triggers all run, **max observed concurrency = 1** (old: 3).
+- `max_two_caps_concurrency_at_two` — 4 rapid triggers all run, **max observed concurrency ≤ 2** (old: 4).
+
+**Grade: MEASURED. Restart, Queued, and `max: N` all implemented — no remaining RunMode deferral.**
+
+## Threat model closed
+
+| Threat | Before (ADR-161) | After (ADR-162) |
+|--------|------------------|-----------------|
+| **Tampered module** — attacker swaps `.wasm` bytes after signing | loaded unconditionally (hash never checked) | rejected: SHA-256 mismatch |
+| **Untrusted publisher** — valid sig from a key the host doesn't trust | loaded (sig/key never read) | rejected: publisher_key not on allowlist |
+| **Unsigned module** — no integrity material at all | loaded | rejected by secure default; loads only under explicit `AllowUnsigned` (loud warn) |
+| **Over-privileged plugin write** — a `light.*` plugin writes `lock.front_door` / `alarm_control_panel.*` | applied (permissions never consulted) | denied: typed `-3` to guest, write not applied |
+| **Run-mode resource exhaustion** — `max`/`Queued` spawn unbounded tasks | unbounded parallel | bounded: Restart cancels, Queued serializes, `max: N` caps at N |
+
+## Remaining honest deferral (Nothing Dropped)
+
+- **Plugin-key provisioning / rotation** — the host's trust allowlist
+  (`PluginPolicy::trusted`) is supplied by the caller; sourcing it from the
+  Cognitum control-plane key store (as `cog-ha-matter` does for Seed keys) and
+  key rotation are **ACCEPTED-FUTURE** (out of M8 scope — same boundary
+  `witness_signing` draws).
+- **`InProcessRuntime` (native first-party plugins)** — has no `.wasm` bytes to
+  hash, so P4/P5 apply only to the WASM (`wasmtime`) path; native plugins remain
+  trusted-by-compilation. Honestly noted, not over-claimed.
+- **HAP real pairing (P2)** — unchanged from ADR-161; out of M8 scope.
+
+## Reproduction (MEASURED)
+
+```bash
+cd v2
+# P4/P5 (wasmtime feature needs rustc 1.91+; workspace pins 1.89 for the rest):
+cargo +1.91.1 test -p homecore-plugins --features wasmtime
+# Bounded RunModes:
+cargo test -p homecore-automation --no-default-features
+# Full workspace still builds (1.89 toolchain, no wasmtime):
+cargo build --workspace --no-default-features
+```
+
+Result at time of writing (all 0 failed):
+- **homecore-plugins** `--features wasmtime` — **32 passed** (lib 23; integration 9). (ADR-161 baseline was 15.)
+- **homecore-automation** `--no-default-features` — **45 passed** (lib 37; `engine_behaviors` 8). (ADR-161 baseline was 42.)
+- Full workspace `cargo build --workspace --no-default-features` succeeds.
+
+## Consequences
+
+- A HOMECORE WASM plugin can no longer be loaded with a tampered binary, an
+  untrusted publisher, or (by default) no signature at all — the trust boundary
+  ADR-161/B5 honestly said was absent is now real (P4).
+- A plugin can no longer write entities outside its declared
+  `homecore_permissions`; the lock/alarm escalation path is closed (P5).
+- The automation engine's `Restart`, `Queued`, and `max: N` run-modes are now
+  bounded as documented — no run-mode claims a capability the code lacks.
+- No new external dependency tree (reuses the cog-ha-matter Ed25519 stack
+  already in the lock); source files kept under the 500-line guideline
+  (`engine.rs` 433, `runmode.rs` 153, `verify.rs` 397, `permissions.rs` 168;
+  `wasmtime_runtime.rs` non-test source < 500, inline WAT tests as ADR-161 left
+  them).

v2/Cargo.lock

@@ -3554,9 +3554,13 @@ name = "homecore-plugins"
 version = "0.1.0-alpha.0"
 dependencies = [
  "async-trait",
+ "base64 0.22.1",
+ "ed25519-dalek",
+ "hex",
  "homecore",
  "serde",
  "serde_json",
+ "sha2",
  "thiserror 1.0.69",
  "tokio",
  "uuid",

v2/crates/homecore-automation/src/engine.rs

@@ -3,14 +3,15 @@
 //!
 //! ADR-129 §2 design: one Tokio task per running automation instance.
 //!
-//! ## Run modes (ADR-161, HC-WS-05)
+//! ## Run modes (ADR-161 §A5 → completed in ADR-162)
 //!
-//! `RunMode::Single` is enforced via a per-automation `AtomicBool`
-//! guard: while an instance is executing, a second trigger is skipped.
-//! `Parallel` (and the as-yet-unbounded `Restart`/`Queued`) spawn a
-//! fresh instance on every trigger. (Before this fix the doc claimed
-//! AtomicBool enforcement but every trigger spawned unbounded parallel
-//! tasks regardless of `mode`.)
+//! Each registered automation owns a [`RunState`] that implements its
+//! `RunMode`: `Single`/`IgnoreFirst` skip re-entrant triggers, `Restart`
+//! aborts the in-flight run and starts a fresh one, `Queued` serializes
+//! runs in arrival order (nothing dropped), `Parallel` spawns on every
+//! trigger, and `max: N` caps concurrency via a per-automation semaphore.
+//! (ADR-161 only honored Single/Parallel; Restart/Queued/max were
+//! honestly documented as unbounded-parallel until ADR-162.)
 //!
 //! ## Time triggers (ADR-161, HC-WS-04)
 //!
@@ -26,7 +27,6 @@
 //! `EvalContext::with_templates`), so `template:` conditions evaluate
 //! against live state instead of always returning false.
 
-use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::{Arc, Mutex};
 
 use chrono::{Local, Timelike};
@@ -34,18 +34,18 @@ use tokio::sync::broadcast;
 
 use homecore::HomeCore;
 
-use crate::action::ExecutionContext;
-use crate::automation::{Automation, RunMode};
+use crate::automation::Automation;
 use crate::condition::EvalContext;
+use crate::runmode::RunState;
 use crate::template::TemplateEnvironment;
 use crate::trigger::{Trigger, TriggerContext};
 
 /// An automation registered with the engine, plus its runtime run-state.
 struct Registered {
     auto: Arc<Automation>,
-    /// `true` while a `Single`-mode instance is executing. Used to
-    /// skip re-entrant triggers (HC-WS-05).
-    running: Arc<AtomicBool>,
+    /// Run-mode machinery (re-entrancy guard / restart abort handle /
+    /// queue mutex / concurrency semaphore) for this automation.
+    run_state: RunState,
 }
 
 /// The automation engine. Holds a HOMECORE handle and a list of registered
@@ -69,9 +69,10 @@ impl AutomationEngine {
 
     /// Register an automation. Can be called before or after `start()`.
     pub fn register(&self, automation: Automation) {
+        let run_state = RunState::new(&automation);
         self.automations.lock().unwrap().push(Registered {
             auto: Arc::new(automation),
-            running: Arc::new(AtomicBool::new(false)),
+            run_state,
         });
     }
 
@@ -118,13 +119,13 @@ impl AutomationEngine {
             loop {
                 match rx.recv().await {
                     Ok(event) => {
-                        let snapshot: Vec<(Arc<Automation>, Arc<AtomicBool>)> = automations
+                        let snapshot: Vec<(Arc<Automation>, RunState)> = automations
                             .lock()
                             .unwrap()
                             .iter()
-                            .map(|r| (Arc::clone(&r.auto), Arc::clone(&r.running)))
+                            .map(|r| (Arc::clone(&r.auto), r.run_state.clone()))
                             .collect();
-                        for (automation, running) in snapshot {
+                        for (automation, run_state) in snapshot {
                             if !automation.enabled {
                                 continue;
                             }
@@ -148,7 +149,7 @@ impl AutomationEngine {
                             if !conditions_pass(&automation, &eval_ctx).await {
                                 continue;
                             }
-                            spawn_run(&hc, automation, running);
+                            run_state.dispatch(&hc, automation);
                         }
                     }
                     Err(broadcast::error::RecvError::Closed) => break,
@@ -183,14 +184,14 @@ impl AutomationEngine {
                         if last_fired_sec.as_deref() == Some(hhmmss.as_str()) {
                             continue;
                         }
-                        let snapshot: Vec<(Arc<Automation>, Arc<AtomicBool>)> = automations
+                        let snapshot: Vec<(Arc<Automation>, RunState)> = automations
                             .lock()
                             .unwrap()
                             .iter()
-                            .map(|r| (Arc::clone(&r.auto), Arc::clone(&r.running)))
+                            .map(|r| (Arc::clone(&r.auto), r.run_state.clone()))
                             .collect();
                         let mut fired_any = false;
-                        for (automation, running) in snapshot {
+                        for (automation, run_state) in snapshot {
                             if !automation.enabled {
                                 continue;
                             }
@@ -208,7 +209,7 @@ impl AutomationEngine {
                             if !conditions_pass(&automation, &eval_ctx).await {
                                 continue;
                             }
-                            spawn_run(&hc, automation, running);
+                            run_state.dispatch(&hc, automation);
                             fired_any = true;
                         }
                         if fired_any {
@@ -231,15 +232,15 @@ impl AutomationEngine {
     /// wall-clock second to roll over. Returns the number of automations
     /// that fired (passed conditions and were spawned).
     pub async fn fire_time_for_test(&self, hhmmss: &str) -> usize {
-        let snapshot: Vec<(Arc<Automation>, Arc<AtomicBool>)> = self
+        let snapshot: Vec<(Arc<Automation>, RunState)> = self
             .automations
             .lock()
             .unwrap()
             .iter()
-            .map(|r| (Arc::clone(&r.auto), Arc::clone(&r.running)))
+            .map(|r| (Arc::clone(&r.auto), r.run_state.clone()))
             .collect();
         let mut fired = 0usize;
-        for (automation, running) in snapshot {
+        for (automation, run_state) in snapshot {
             if !automation.enabled {
                 continue;
             }
@@ -254,7 +255,7 @@ impl AutomationEngine {
             if !conditions_pass(&automation, &eval_ctx).await {
                 continue;
             }
-            spawn_run(&self.hc, automation, running);
+            run_state.dispatch(&self.hc, automation);
             fired += 1;
         }
         fired
@@ -281,36 +282,6 @@ fn time_at_matches(at: &str, hhmmss: &str) -> bool {
     normalized == hhmmss
 }
 
-/// Spawn an automation run, honoring `RunMode::Single` re-entrancy
-/// guard (HC-WS-05). For `Single`/`IgnoreFirst` modes a run already in
-/// flight causes the new trigger to be skipped; the `running` flag is
-/// cleared when the run finishes.
-fn spawn_run(hc: &HomeCore, automation: Arc<Automation>, running: Arc<AtomicBool>) {
-    let single = matches!(automation.mode, RunMode::Single | RunMode::IgnoreFirst);
-    if single {
-        // Try to claim the running slot; if already running, skip.
-        if running
-            .compare_exchange(false, true, Ordering::SeqCst, Ordering::SeqCst)
-            .is_err()
-        {
-            return;
-        }
-    }
-    let hc_clone = hc.clone();
-    tokio::spawn(async move {
-        let mut exec_ctx = ExecutionContext::new(hc_clone, automation.id.clone());
-        for action in &automation.action {
-            if let Err(e) = action.execute(&mut exec_ctx).await {
-                eprintln!("[homecore-automation] action error in {}: {e}", automation.id);
-                break;
-            }
-        }
-        if single {
-            running.store(false, Ordering::SeqCst);
-        }
-    });
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;

v2/crates/homecore-automation/src/lib.rs

@@ -19,6 +19,7 @@ pub mod condition;
 pub mod action;
 pub mod template;
 pub mod engine;
+pub mod runmode;
 pub mod error;
 
 pub use automation::{Automation, RunMode};

v2/crates/homecore-automation/src/runmode.rs

@@ -0,0 +1,153 @@
+//! Per-automation run-mode machinery (ADR-162, completes ADR-161 §A5).
+//!
+//! ADR-161 implemented `RunMode::Single` (a per-automation `AtomicBool`
+//! re-entrancy guard) and `Parallel`, but honestly left `Restart`, `Queued`
+//! and `max: N` as "ACCEPTED-FUTURE / unbounded parallel" — every non-Single
+//! mode spawned an unbounded task. This module makes them real:
+//!
+//! | Mode | Semantics implemented |
+//! |------|-----------------------|
+//! | `Single` / `IgnoreFirst` | re-entrancy guard: skip while a run is in flight (ADR-161). |
+//! | `Restart` | **cancel** the in-flight run (`tokio::task::AbortHandle`) and start a fresh one. |
+//! | `Queued` | **serialize**: runs execute sequentially in arrival order via a per-automation async mutex — nothing is dropped. |
+//! | `Parallel` | spawn on every trigger (optionally capped, see below). |
+//! | `max: N` | cap concurrency at **N** via a per-automation semaphore; triggers beyond N **queue** (await a permit) rather than running concurrently — matching HA's bounded `parallel`/`queued`. |
+//!
+//! Each registered automation owns one [`RunState`]; the engine calls
+//! [`RunState::dispatch`] on every (trigger + conditions-passed) event.
+
+use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::{Arc, Mutex};
+
+use tokio::sync::{Mutex as AsyncMutex, Semaphore};
+
+use homecore::HomeCore;
+
+use crate::action::ExecutionContext;
+use crate::automation::{Automation, RunMode};
+
+/// Per-automation runtime state backing the run-mode dispatch.
+///
+/// Cheap to clone (all fields are `Arc`); the engine clones it into each
+/// spawned run so the machinery (abort handle, queue mutex, semaphore) is
+/// shared across all triggers of the same automation.
+#[derive(Clone)]
+pub struct RunState {
+    /// `Single`/`IgnoreFirst` re-entrancy guard (ADR-161 §A5).
+    running: Arc<AtomicBool>,
+    /// `Restart`: handle to the currently-running action task, so a new
+    /// trigger can abort it before starting a fresh one.
+    current: Arc<Mutex<Option<tokio::task::AbortHandle>>>,
+    /// `Queued`: serializes runs in arrival order (one at a time, FIFO via
+    /// fair async mutex acquisition).
+    queue_lock: Arc<AsyncMutex<()>>,
+    /// `max: N` (and bounded `Parallel`): caps concurrent runs at N.
+    /// `None` when no cap applies.
+    semaphore: Option<Arc<Semaphore>>,
+}
+
+impl RunState {
+    /// Build run-state for an automation, sizing the concurrency semaphore
+    /// from its `max:` field (only meaningful for `Queued`/`Parallel`).
+    pub fn new(automation: &Automation) -> Self {
+        let semaphore = automation
+            .max
+            .filter(|n| *n > 0)
+            .map(|n| Arc::new(Semaphore::new(n)));
+        Self {
+            running: Arc::new(AtomicBool::new(false)),
+            current: Arc::new(Mutex::new(None)),
+            queue_lock: Arc::new(AsyncMutex::new(())),
+            semaphore,
+        }
+    }
+
+    /// Dispatch one trigger for `automation` according to its `RunMode`.
+    /// Honors Single re-entrancy, Restart cancel-and-replace, Queued
+    /// serialization, and `max:` concurrency capping.
+    pub fn dispatch(&self, hc: &HomeCore, automation: Arc<Automation>) {
+        match automation.mode {
+            RunMode::Single | RunMode::IgnoreFirst => self.dispatch_single(hc, automation),
+            RunMode::Restart => self.dispatch_restart(hc, automation),
+            RunMode::Queued => self.dispatch_queued(hc, automation),
+            RunMode::Parallel => self.dispatch_parallel(hc, automation),
+        }
+    }
+
+    /// `Single`: skip if a run is already in flight; clear the flag on done.
+    fn dispatch_single(&self, hc: &HomeCore, automation: Arc<Automation>) {
+        if self
+            .running
+            .compare_exchange(false, true, Ordering::SeqCst, Ordering::SeqCst)
+            .is_err()
+        {
+            return; // already running — skip re-entrant trigger.
+        }
+        let hc = hc.clone();
+        let running = Arc::clone(&self.running);
+        tokio::spawn(async move {
+            run_actions(&hc, &automation).await;
+            running.store(false, Ordering::SeqCst);
+        });
+    }
+
+    /// `Restart`: abort the in-flight run (if any), then start a fresh one
+    /// and record its abort handle.
+    fn dispatch_restart(&self, hc: &HomeCore, automation: Arc<Automation>) {
+        // Abort any prior run before starting the new one.
+        if let Some(prev) = self.current.lock().unwrap().take() {
+            prev.abort();
+        }
+        let hc = hc.clone();
+        let slot = Arc::clone(&self.current);
+        let handle = tokio::spawn(async move {
+            run_actions(&hc, &automation).await;
+        });
+        *slot.lock().unwrap() = Some(handle.abort_handle());
+    }
+
+    /// `Queued`: serialize via the per-automation async mutex. Each trigger
+    /// spawns a task that waits its turn, so all triggers run in arrival
+    /// order, one at a time — nothing is dropped.
+    fn dispatch_queued(&self, hc: &HomeCore, automation: Arc<Automation>) {
+        let hc = hc.clone();
+        let lock = Arc::clone(&self.queue_lock);
+        let sem = self.semaphore.clone();
+        tokio::spawn(async move {
+            // Optional `max:` cap still applies on top of serialization.
+            let _permit = match &sem {
+                Some(s) => Some(s.acquire().await.expect("semaphore not closed")),
+                None => None,
+            };
+            let _guard = lock.lock().await; // FIFO turn — sequential execution.
+            run_actions(&hc, &automation).await;
+        });
+    }
+
+    /// `Parallel`: spawn on every trigger, capped at `max:` if set.
+    fn dispatch_parallel(&self, hc: &HomeCore, automation: Arc<Automation>) {
+        let hc = hc.clone();
+        let sem = self.semaphore.clone();
+        tokio::spawn(async move {
+            let _permit = match &sem {
+                Some(s) => Some(s.acquire().await.expect("semaphore not closed")),
+                None => None,
+            };
+            run_actions(&hc, &automation).await;
+        });
+    }
+}
+
+/// Execute an automation's action sequence once.
+async fn run_actions(hc: &HomeCore, automation: &Automation) {
+    let mut exec_ctx = ExecutionContext::new(hc.clone(), automation.id.clone());
+    for action in &automation.action {
+        if let Err(e) = action.execute(&mut exec_ctx).await {
+            eprintln!(
+                "[homecore-automation] action error in {}: {e}",
+                automation.id
+            );
+            break;
+        }
+    }
+}

v2/crates/homecore-automation/tests/engine_behaviors.rs

@@ -257,3 +257,162 @@ async fn template_condition_evaluates_false_blocks_action() {
     sleep(Duration::from_millis(50)).await;
     assert_eq!(log.lock().unwrap().len(), 0, "false template condition should block the action");
 }
+
+// ── ADR-162 (completes ADR-161 §A5): bounded RunModes ───────────────
+//
+// ADR-161 honored only Single/Parallel; Restart/Queued/max were honestly
+// documented as unbounded-parallel. These tests drive the real
+// Restart/Queued/max machinery and FAIL on the old engine (where every
+// non-Single mode spawned an unbounded parallel task).
+
+/// A service that increments a live concurrency gauge on entry, sleeps,
+/// then decrements — recording the maximum concurrency ever observed and
+/// the total number of completed runs. Returns `(max_concurrency, completed)`.
+async fn register_gauge(
+    hc: &HomeCore,
+    domain: &str,
+    service: &str,
+    work: Duration,
+) -> (Arc<AtomicUsize>, Arc<AtomicUsize>) {
+    let live = Arc::new(AtomicUsize::new(0));
+    let max_seen = Arc::new(AtomicUsize::new(0));
+    let completed = Arc::new(AtomicUsize::new(0));
+    let (l, m, c) = (Arc::clone(&live), Arc::clone(&max_seen), Arc::clone(&completed));
+    hc.services()
+        .register(
+            ServiceName::new(domain, service),
+            FnHandler(move |_call: ServiceCall| {
+                let (l, m, c) = (Arc::clone(&l), Arc::clone(&m), Arc::clone(&c));
+                async move {
+                    let now = l.fetch_add(1, Ordering::SeqCst) + 1;
+                    m.fetch_max(now, Ordering::SeqCst);
+                    sleep(work).await;
+                    l.fetch_sub(1, Ordering::SeqCst);
+                    c.fetch_add(1, Ordering::SeqCst);
+                    Ok(serde_json::Value::Null)
+                }
+            }),
+        )
+        .await;
+    (max_seen, completed)
+}
+
+fn state_auto(id: &str, entity: &str, domain: &str, service: &str) -> Automation {
+    Automation::new(
+        id,
+        vec![Trigger::State {
+            entity_id: EntityId::parse(entity).unwrap(),
+            from: None,
+            to: None,
+        }],
+        vec![Action::ServiceCall {
+            domain: domain.into(),
+            service: service.into(),
+            data: serde_json::json!({}),
+        }],
+    )
+}
+
+// ── Restart: cancels the in-flight run ─────────────────────────────
+#[tokio::test]
+async fn restart_mode_cancels_prior_run() {
+    let hc = HomeCore::new();
+    // Each run sleeps 300ms before recording completion.
+    let (_max, completed) =
+        register_gauge(&hc, "light", "slow", Duration::from_millis(300)).await;
+
+    let engine = AutomationEngine::new(hc.clone());
+    let mut auto = state_auto("restart_auto", "switch.r", "light", "slow");
+    auto.mode = RunMode::Restart;
+    engine.register(auto);
+    let _handle = engine.start();
+
+    // Trigger 1 starts the slow run.
+    hc.states().set(EntityId::parse("switch.r").unwrap(), "a", serde_json::json!({}), Context::new());
+    sleep(Duration::from_millis(80)).await;
+    // Trigger 2 arrives mid-run → must ABORT run 1 and start run 2.
+    hc.states().set(EntityId::parse("switch.r").unwrap(), "b", serde_json::json!({}), Context::new());
+
+    // Wait long enough for run 2 (started ~80ms in) to finish, but run 1
+    // (aborted at ~80ms, would have finished at ~300ms) must NOT complete.
+    sleep(Duration::from_millis(400)).await;
+    assert_eq!(
+        completed.load(Ordering::SeqCst),
+        1,
+        "Restart must cancel the in-flight run: exactly the restarted run completes (not both). \
+         On the old engine both ran to completion → 2."
+    );
+}
+
+// ── Queued: serialize N rapid triggers, all run, never concurrent ──
+#[tokio::test]
+async fn queued_mode_runs_sequentially_not_concurrently() {
+    let hc = HomeCore::new();
+    let (max_seen, completed) =
+        register_gauge(&hc, "light", "slow", Duration::from_millis(120)).await;
+
+    let engine = AutomationEngine::new(hc.clone());
+    let mut auto = state_auto("queued_auto", "switch.q", "light", "slow");
+    auto.mode = RunMode::Queued;
+    engine.register(auto);
+    let _handle = engine.start();
+
+    // Three rapid triggers.
+    for v in ["a", "b", "c"] {
+        hc.states().set(EntityId::parse("switch.q").unwrap(), v, serde_json::json!({}), Context::new());
+        sleep(Duration::from_millis(10)).await;
+    }
+
+    // 3 runs × 120ms serialized ≈ 360ms; wait generously.
+    sleep(Duration::from_millis(600)).await;
+    assert_eq!(
+        completed.load(Ordering::SeqCst),
+        3,
+        "Queued must run every trigger (nothing dropped)"
+    );
+    assert_eq!(
+        max_seen.load(Ordering::SeqCst),
+        1,
+        "Queued must never run two instances concurrently. On the old engine all 3 ran in \
+         parallel → max concurrency 3."
+    );
+}
+
+// ── max: 2 → never more than 2 concurrent ──────────────────────────
+#[tokio::test]
+async fn max_two_caps_concurrency_at_two() {
+    let hc = HomeCore::new();
+    let (max_seen, completed) =
+        register_gauge(&hc, "light", "slow", Duration::from_millis(150)).await;
+
+    let engine = AutomationEngine::new(hc.clone());
+    let mut auto = state_auto("max_auto", "switch.m", "light", "slow");
+    auto.mode = RunMode::Parallel;
+    auto.max = Some(2);
+    engine.register(auto);
+    let _handle = engine.start();
+
+    // Four rapid triggers — without the cap all 4 would run at once.
+    for v in ["a", "b", "c", "d"] {
+        hc.states().set(EntityId::parse("switch.m").unwrap(), v, serde_json::json!({}), Context::new());
+        sleep(Duration::from_millis(10)).await;
+    }
+
+    sleep(Duration::from_millis(600)).await;
+    assert_eq!(
+        completed.load(Ordering::SeqCst),
+        4,
+        "max:2 must still run all 4 triggers (queued beyond the cap, not dropped)"
+    );
+    assert!(
+        max_seen.load(Ordering::SeqCst) <= 2,
+        "max:2 must never exceed 2 concurrent runs (observed {}). On the old engine all 4 ran \
+         concurrently → 4.",
+        max_seen.load(Ordering::SeqCst)
+    );
+    assert!(
+        max_seen.load(Ordering::SeqCst) >= 2,
+        "max:2 should reach the cap of 2 with 4 rapid triggers (observed {})",
+        max_seen.load(Ordering::SeqCst)
+    );
+}

v2/crates/homecore-plugins/Cargo.toml

@@ -50,6 +50,15 @@ serde_json = "1"
 # UUIDs for config entry IDs in host_abi.rs.
 uuid = { version = "1", features = ["v4"] }
 
+# ── ADR-162 P4: plugin signature + integrity verification ──────────────────
+# Reuses the same in-repo crypto stack as cog-ha-matter (witness_signing.rs):
+# Ed25519 over a SHA-256 module digest. All four are already in the workspace
+# Cargo.lock (cog-ha-matter / bfld pull them in) — no new external dep tree.
+ed25519-dalek = "2.1"
+sha2 = { workspace = true }
+hex = "0.4"
+base64 = "0.22"
+
 # Optional Wasmtime runtime (P2, default-off — 30 MB dep).
 # Bumped from 25.0.3 → 42 to remediate RUSTSEC-2026-0095 and RUSTSEC-2026-0096
 # (Cranelift/Winch sandbox-escape CVEs, CVSS 9.0 — iter-11 security sprint HC-03/04).

v2/crates/homecore-plugins/src/error.rs

@@ -25,6 +25,18 @@ pub enum PluginError {
     #[error("plugin setup failed: {0}")]
     SetupFailed(String),
 
+    /// The plugin failed signature/integrity verification (ADR-162 P4):
+    /// hash mismatch, bad signature, untrusted publisher, or unsigned
+    /// module under a non-dev trust policy.
+    #[error("plugin signature rejected: {0}")]
+    SignatureRejected(String),
+
+    /// A plugin attempted a host call (e.g. `hc_state_set`) on an entity
+    /// it did not declare in `homecore_permissions` (ADR-162 P5 authority
+    /// isolation).
+    #[error("plugin permission denied: {0}")]
+    PermissionDenied(String),
+
     /// The plugin's `unload` hook returned an error.
     #[error("plugin unload failed: {0}")]
     UnloadFailed(String),

v2/crates/homecore-plugins/src/lib.rs

@@ -22,8 +22,16 @@
 //! - Host ABI wiring: `hc_state_get`, `hc_state_set`, `hc_event_fire`, etc.
 //!   (P2 — requires ADR-127 state machine API freeze first).
 //! - Config entry lifecycle + hot-load (P3).
-//! - Cog registry distribution + Ed25519 signature verification (P4).
-//! - Permission enforcement (P5).
+//!
+//! ## Now enforced (ADR-162)
+//!
+//! - **Ed25519 signature + SHA-256 integrity verification (P4)** — see
+//!   [`verify`]: the plugin load path hashes the real `.wasm` bytes, checks
+//!   the manifest `wasm_module_hash`, verifies `wasm_module_sig` against
+//!   `publisher_key`, and enforces a [`verify::PluginPolicy`] allowlist.
+//! - **Permission / authority isolation (P5)** — see [`permissions`]: a
+//!   plugin's `hc_state_set` writes are gated against the entity domains/
+//!   globs it declared in `homecore_permissions`.
 //!
 //! ## Feature flags
 //!
@@ -35,9 +43,11 @@
 pub mod error;
 pub mod host_abi;
 pub mod manifest;
+pub mod permissions;
 pub mod plugin;
 pub mod registry;
 pub mod runtime;
+pub mod verify;
 
 #[cfg(feature = "wasmtime")]
 pub mod wasmtime_runtime;
@@ -45,9 +55,11 @@ pub mod wasmtime_runtime;
 pub use error::PluginError;
 pub use host_abi::{ConfigEntryJson, StateChangedEventJson};
 pub use manifest::{IotClass, IntegrationType, PluginManifest};
+pub use permissions::PermissionSet;
 pub use plugin::{HomeCorePlugin, PluginId};
 pub use registry::PluginRegistry;
 pub use runtime::{InProcessRuntime, LoadedPlugin, PluginRuntime};
+pub use verify::{verify_module, PluginPolicy};
 
 #[cfg(feature = "wasmtime")]
 pub use wasmtime_runtime::{WasmPlugin, WasmtimeRuntime};

v2/crates/homecore-plugins/src/manifest.rs

@@ -85,24 +85,26 @@ pub struct PluginManifest {
 
     /// [HOMECORE] `sha256:<hex>` hash of the wasm binary.
     ///
-    /// **(P4 — not yet enforced, ADR-161/B5):** this field is parsed and
-    /// round-tripped but is NOT verified before execution. The hash/sig
-    /// gate lands in P4; until then the presence of this field implies no
-    /// integrity guarantee.
+    /// **(P4 — ENFORCED, ADR-162):** `verify::verify_module` computes the
+    /// SHA-256 of the real `.wasm` bytes on load and rejects the module if
+    /// it does not equal this hash (tamper detection). See [`crate::verify`].
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub wasm_module_hash: Option<String>,
 
     /// [HOMECORE] Ed25519 signature of the wasm binary hash (`ed25519:<base64>`).
     ///
-    /// **(P4 — not yet enforced, ADR-161/B5):** parsed but never checked.
-    /// No signature verification happens before a plugin runs.
+    /// **(P4 — ENFORCED, ADR-162):** verified against `publisher_key` over
+    /// the SHA-256 module digest before instantiation. A bad/forged/absent
+    /// signature is rejected under the secure trust policy (the
+    /// `cog-ha-matter::witness_signing` Ed25519 pattern is reused).
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub wasm_module_sig: Option<String>,
 
     /// [HOMECORE] Ed25519 public key of the plugin publisher.
     ///
-    /// **(P4 — not yet enforced, ADR-161/B5):** parsed but never used to
-    /// verify `wasm_module_sig`.
+    /// **(P4 — ENFORCED, ADR-162):** used to verify `wasm_module_sig`, and
+    /// checked against the host's [`crate::verify::PluginPolicy`] trust
+    /// allowlist — an unknown publisher is rejected by the secure default.
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub publisher_key: Option<String>,
 
@@ -115,6 +117,12 @@ pub struct PluginManifest {
     pub host_imports_required: Vec<String>,
 
     /// [HOMECORE] Coarse-grained permission claims (glob patterns).
+    ///
+    /// **(P5 — ENFORCED, ADR-162):** `state:write:<glob>` (or a bare entity
+    /// glob like `light.*`) grants are parsed into a
+    /// [`crate::permissions::PermissionSet` ] and consulted by the
+    /// `hc_state_set` host import. A plugin can no longer write an entity it
+    /// did not declare; a plugin with no write grants can write nothing.
     #[serde(default)]
     pub homecore_permissions: Vec<PermissionClaim>,
 

v2/crates/homecore-plugins/src/permissions.rs

@@ -0,0 +1,168 @@
+//! Plugin authority / capability isolation (ADR-162, P5).
+//!
+//! Wasmtime already gives a plugin **memory** isolation — it cannot read
+//! another plugin's linear memory. It does NOT, by itself, stop a plugin
+//! from using a host import to write any entity it likes. Before this fix
+//! `hc_state_set` happily let any plugin write `lock.front_door` or
+//! `alarm_control_panel.*`, and the manifest's `homecore_permissions`
+//! claims were parsed but **never consulted** (ADR-161 deferred P5).
+//!
+//! This module adds **authority isolation**: a plugin may only write
+//! entities its manifest declared. The host import consults a
+//! [`PermissionSet`] before applying any state write and returns a typed
+//! error to the guest (it does **not** panic the host) on a violation.
+//!
+//! ## Permission grammar
+//!
+//! Each entry in `homecore_permissions` is one of:
+//!
+//!   * a bare entity glob — `"light.*"`, `"light.kitchen"`, `"*"`;
+//!   * the explicit capability form `"state:write:<glob>"` (the form the
+//!     ADR-128 manifest doc shows), e.g. `"state:write:sensor.*"`.
+//!
+//! A glob supports a single trailing `*` (HA-style domain wildcards:
+//! `light.*` matches every `light` entity) and a leading-or-bare `*`
+//! (`*` = everything). Exact strings match exactly. A plugin with **no**
+//! `state:write` entries can write **nothing** — the secure default.
+
+use crate::manifest::PluginManifest;
+
+/// The set of entity-write permissions a plugin holds, distilled from its
+/// manifest `homecore_permissions` at load time.
+#[derive(Debug, Clone, Default)]
+pub struct PermissionSet {
+    /// Glob patterns the plugin may write (state:write authority). Empty =
+    /// the plugin may write nothing.
+    write_globs: Vec<String>,
+}
+
+impl PermissionSet {
+    /// Build a permission set from a manifest's `homecore_permissions`.
+    ///
+    /// Only `state:write` authority is modelled here (the host import this
+    /// gates is `hc_state_set`). A bare glob (`"light.*"`) is treated as a
+    /// write grant; the explicit `"state:write:<glob>"` form is also
+    /// accepted. Other capability strings (`state:read:*`, future verbs)
+    /// are ignored for write-gating purposes.
+    pub fn from_manifest(manifest: &PluginManifest) -> Self {
+        let mut write_globs = Vec::new();
+        for claim in &manifest.homecore_permissions {
+            let claim = claim.trim();
+            if let Some(glob) = claim.strip_prefix("state:write:") {
+                write_globs.push(glob.trim().to_string());
+            } else if claim.starts_with("state:read:") {
+                // read authority — not relevant to write gating.
+            } else if !claim.is_empty() {
+                // Bare glob — treat as a write grant.
+                write_globs.push(claim.to_string());
+            }
+        }
+        Self { write_globs }
+    }
+
+    /// An all-allowing set (equivalent to a `"*"` grant). Used by the
+    /// legacy permission-free `WasmtimeRuntime::load_wasm` path so existing
+    /// callers/tests that do not supply a manifest keep working; the
+    /// permission-gated path uses [`Self::from_manifest`].
+    pub fn allow_all() -> Self {
+        Self {
+            write_globs: vec!["*".to_string()],
+        }
+    }
+
+    /// May this plugin write the given entity id (e.g. `"light.kitchen"`)?
+    pub fn may_write(&self, entity_id: &str) -> bool {
+        self.write_globs.iter().any(|g| glob_matches(g, entity_id))
+    }
+
+    /// Number of write-grant globs (0 = can write nothing).
+    pub fn write_grant_count(&self) -> usize {
+        self.write_globs.len()
+    }
+}
+
+/// Match `entity_id` against a single glob pattern.
+///
+/// Supported forms:
+///   * `"*"`              → matches anything.
+///   * `"light.*"`        → trailing wildcard: any id with the `light.` prefix.
+///   * `"light.kitchen"`  → exact match.
+fn glob_matches(pattern: &str, entity_id: &str) -> bool {
+    if pattern == "*" {
+        return true;
+    }
+    if let Some(prefix) = pattern.strip_suffix('*') {
+        return entity_id.starts_with(prefix);
+    }
+    pattern == entity_id
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn manifest_with(perms: &[&str]) -> PluginManifest {
+        PluginManifest {
+            domain: "p".into(),
+            name: "P".into(),
+            version: "1".into(),
+            documentation: None,
+            iot_class: None,
+            config_flow: false,
+            integration_type: None,
+            dependencies: vec![],
+            requirements: vec![],
+            wasm_module: None,
+            wasm_module_hash: None,
+            wasm_module_sig: None,
+            publisher_key: None,
+            min_homecore_version: None,
+            host_imports_required: vec![],
+            homecore_permissions: perms.iter().map(|s| s.to_string()).collect(),
+            cog_id: None,
+        }
+    }
+
+    #[test]
+    fn domain_glob_allows_same_domain_only() {
+        let ps = PermissionSet::from_manifest(&manifest_with(&["light.*"]));
+        assert!(ps.may_write("light.kitchen"));
+        assert!(ps.may_write("light.bedroom"));
+        assert!(!ps.may_write("lock.front_door"));
+        assert!(!ps.may_write("alarm_control_panel.home"));
+    }
+
+    #[test]
+    fn no_permissions_can_write_nothing() {
+        let ps = PermissionSet::from_manifest(&manifest_with(&[]));
+        assert_eq!(ps.write_grant_count(), 0);
+        assert!(!ps.may_write("light.kitchen"));
+        assert!(!ps.may_write("sensor.temp"));
+    }
+
+    #[test]
+    fn explicit_state_write_form_is_honored() {
+        let ps = PermissionSet::from_manifest(&manifest_with(&["state:write:sensor.*"]));
+        assert!(ps.may_write("sensor.temp"));
+        assert!(!ps.may_write("light.kitchen"));
+    }
+
+    #[test]
+    fn read_grants_do_not_confer_write() {
+        let ps = PermissionSet::from_manifest(&manifest_with(&["state:read:lock.*"]));
+        assert!(!ps.may_write("lock.front_door"));
+    }
+
+    #[test]
+    fn exact_entity_grant_is_scoped() {
+        let ps = PermissionSet::from_manifest(&manifest_with(&["light.kitchen"]));
+        assert!(ps.may_write("light.kitchen"));
+        assert!(!ps.may_write("light.bedroom"));
+    }
+
+    #[test]
+    fn wildcard_grants_everything() {
+        let ps = PermissionSet::from_manifest(&manifest_with(&["*"]));
+        assert!(ps.may_write("lock.front_door"));
+    }
+}

v2/crates/homecore-plugins/src/verify.rs

@@ -0,0 +1,397 @@
+//! Plugin signature & integrity verification (ADR-162, P4).
+//!
+//! ADR-161/B5 honestly relabelled the manifest's `wasm_module_hash` /
+//! `wasm_module_sig` / `publisher_key` fields as "(P4 — not yet enforced)":
+//! they were parsed and round-tripped but **never checked** before a plugin
+//! ran. This module makes that claim TRUE — it is the real verification gate
+//! the plugin load path runs before instantiating any `.wasm` module.
+//!
+//! ## What is verified, in order
+//!
+//! 1. **Module hash** — SHA-256 of the actual `.wasm` bytes must equal the
+//!    manifest's `wasm_module_hash` (`sha256:<hex>`). A tampered module
+//!    (one byte changed) fails here.
+//! 2. **Ed25519 signature** — `wasm_module_sig` (`ed25519:<base64>`, 64-byte
+//!    raw signature) must verify over the **32-byte SHA-256 digest** under
+//!    the `publisher_key` (`ed25519:<base64>`, 32-byte raw verifying key).
+//! 3. **Trust policy** — the `publisher_key` must be on the configured
+//!    allowlist, unless [`PluginPolicy::AllowUnsigned`] is in force (a loud
+//!    dev escape hatch).
+//!
+//! The crypto mirrors the in-repo Ed25519 pattern from
+//! `cog-ha-matter::witness_signing` (same `ed25519-dalek` 2.x API, same
+//! deterministic-test-key convention). SHA-256 matches the `sha256:` prefix
+//! the manifest doc already declared for `wasm_module_hash`, and the
+//! `cog-ha-matter` cog manifest's `binary_sha256` hex convention.
+//!
+//! ## Secure default
+//!
+//! [`PluginPolicy::trusted`] (the production constructor) **rejects**:
+//!   * an unsigned module (no hash / sig / key),
+//!   * a signature from a key not on the allowlist,
+//!   * any hash or signature mismatch.
+//!
+//! Only [`PluginPolicy::AllowUnsigned`] loosens this, and every load it
+//! waves through emits a `warn`-level log line so it cannot pass silently.
+
+use base64::Engine as _;
+use ed25519_dalek::{Signature, Verifier, VerifyingKey};
+use sha2::{Digest, Sha256};
+
+use crate::error::PluginError;
+use crate::manifest::PluginManifest;
+
+/// Trust policy governing which plugins may load.
+///
+/// The production path uses [`PluginPolicy::trusted`] with an explicit
+/// allowlist of publisher verifying keys. [`PluginPolicy::AllowUnsigned`]
+/// is the dev escape hatch — it loads anything (even unsigned modules) but
+/// logs a loud warning per load.
+#[derive(Debug, Clone)]
+pub enum PluginPolicy {
+    /// Secure default: a plugin loads only if its module hash matches, its
+    /// Ed25519 signature verifies, AND its publisher key is in this
+    /// allowlist. Each entry is the 32-byte raw Ed25519 verifying key.
+    Trusted { allowlist: Vec<[u8; 32]> },
+    /// Dev-only: skip signature/allowlist enforcement. Hash is still
+    /// checked when a `wasm_module_hash` is present (cheap integrity), but
+    /// unsigned / unknown-publisher modules are allowed. Every load logs a
+    /// loud `warn`.
+    AllowUnsigned,
+}
+
+impl PluginPolicy {
+    /// Construct the secure (production) policy from a list of trusted
+    /// publisher keys, each encoded as `ed25519:<base64>` (the same form
+    /// the manifest `publisher_key` uses).
+    pub fn trusted(publisher_keys: &[&str]) -> Result<Self, PluginError> {
+        let mut allowlist = Vec::with_capacity(publisher_keys.len());
+        for k in publisher_keys {
+            allowlist.push(decode_verifying_key(k)?.to_bytes());
+        }
+        Ok(PluginPolicy::Trusted { allowlist })
+    }
+
+    /// Secure policy that trusts no publisher at all — every signed or
+    /// unsigned module is rejected. Useful as a strict default.
+    pub fn deny_all() -> Self {
+        PluginPolicy::Trusted { allowlist: vec![] }
+    }
+
+    fn is_dev(&self) -> bool {
+        matches!(self, PluginPolicy::AllowUnsigned)
+    }
+
+    fn allows(&self, key: &VerifyingKey) -> bool {
+        match self {
+            PluginPolicy::AllowUnsigned => true,
+            PluginPolicy::Trusted { allowlist } => {
+                allowlist.iter().any(|k| k == &key.to_bytes())
+            }
+        }
+    }
+}
+
+/// Verify a `.wasm` module's integrity and signature against its manifest,
+/// under the given trust `policy`. Returns `Ok(())` only if the module may
+/// be instantiated.
+///
+/// On [`PluginPolicy::AllowUnsigned`] this still checks any present hash,
+/// but waves through missing/untrusted signatures with a loud `warn`.
+pub fn verify_module(
+    manifest: &PluginManifest,
+    wasm_bytes: &[u8],
+    policy: &PluginPolicy,
+) -> Result<(), PluginError> {
+    let signed = manifest.wasm_module_hash.is_some()
+        || manifest.wasm_module_sig.is_some()
+        || manifest.publisher_key.is_some();
+
+    if !signed {
+        // No integrity material at all.
+        if policy.is_dev() {
+            eprintln!(
+                "[PLUGIN WARN] loading UNSIGNED plugin `{}` — no wasm_module_hash/sig/publisher_key. \
+                 AllowUnsigned dev policy is active; this is INSECURE and must not be used in production.",
+                manifest.domain
+            );
+            return Ok(());
+        }
+        return Err(PluginError::SignatureRejected(format!(
+            "plugin `{}` is unsigned (no wasm_module_hash/sig/publisher_key) and the trust policy \
+             rejects unsigned modules; set PluginPolicy::AllowUnsigned to override in dev",
+            manifest.domain
+        )));
+    }
+
+    // (1) Hash check — always enforced when a hash is declared.
+    let digest = sha256_digest(wasm_bytes);
+    if let Some(declared) = &manifest.wasm_module_hash {
+        let expected = parse_sha256(declared)?;
+        if expected != digest {
+            return Err(PluginError::SignatureRejected(format!(
+                "plugin `{}` wasm hash mismatch: module does not match manifest wasm_module_hash \
+                 (tampered or wrong binary)",
+                manifest.domain
+            )));
+        }
+    } else if !policy.is_dev() {
+        return Err(PluginError::SignatureRejected(format!(
+            "plugin `{}` carries a signature/publisher_key but no wasm_module_hash to bind it to",
+            manifest.domain
+        )));
+    }
+
+    // (2) Signature check + (3) allowlist.
+    match (&manifest.wasm_module_sig, &manifest.publisher_key) {
+        (Some(sig_str), Some(key_str)) => {
+            let key = decode_verifying_key(key_str)?;
+            let sig = decode_signature(sig_str)?;
+            key.verify(&digest, &sig).map_err(|_| {
+                PluginError::SignatureRejected(format!(
+                    "plugin `{}` Ed25519 signature does not verify over the module hash under \
+                     publisher_key",
+                    manifest.domain
+                ))
+            })?;
+            if !policy.allows(&key) {
+                if policy.is_dev() {
+                    eprintln!(
+                        "[PLUGIN WARN] plugin `{}` is validly signed but its publisher_key is NOT on \
+                         the trust allowlist; AllowUnsigned dev policy loads it anyway.",
+                        manifest.domain
+                    );
+                    return Ok(());
+                }
+                return Err(PluginError::SignatureRejected(format!(
+                    "plugin `{}` is validly signed but its publisher_key is not on the trust \
+                     allowlist (untrusted publisher)",
+                    manifest.domain
+                )));
+            }
+            Ok(())
+        }
+        _ => {
+            // Hash present but signature/key incomplete.
+            if policy.is_dev() {
+                eprintln!(
+                    "[PLUGIN WARN] plugin `{}` has a hash but no complete Ed25519 signature; \
+                     AllowUnsigned dev policy loads it anyway.",
+                    manifest.domain
+                );
+                return Ok(());
+            }
+            Err(PluginError::SignatureRejected(format!(
+                "plugin `{}` is missing a complete wasm_module_sig + publisher_key pair; the trust \
+                 policy requires a valid signature",
+                manifest.domain
+            )))
+        }
+    }
+}
+
+/// SHA-256 of `bytes` as a 32-byte digest.
+fn sha256_digest(bytes: &[u8]) -> [u8; 32] {
+    let mut hasher = Sha256::new();
+    hasher.update(bytes);
+    hasher.finalize().into()
+}
+
+/// Parse a `sha256:<hex>` manifest hash into a 32-byte digest.
+fn parse_sha256(s: &str) -> Result<[u8; 32], PluginError> {
+    let hex_part = s.strip_prefix("sha256:").ok_or_else(|| {
+        PluginError::InvalidManifest(format!(
+            "wasm_module_hash must be `sha256:<hex>`, got {s:?}"
+        ))
+    })?;
+    let raw = hex::decode(hex_part).map_err(|e| {
+        PluginError::InvalidManifest(format!("wasm_module_hash hex decode: {e}"))
+    })?;
+    raw.try_into().map_err(|v: Vec<u8>| {
+        PluginError::InvalidManifest(format!(
+            "wasm_module_hash must decode to 32 bytes, got {}",
+            v.len()
+        ))
+    })
+}
+
+/// Decode an `ed25519:<base64>` 32-byte verifying key.
+fn decode_verifying_key(s: &str) -> Result<VerifyingKey, PluginError> {
+    let b64 = s.strip_prefix("ed25519:").ok_or_else(|| {
+        PluginError::InvalidManifest(format!(
+            "publisher_key must be `ed25519:<base64>`, got {s:?}"
+        ))
+    })?;
+    let raw = base64::engine::general_purpose::STANDARD
+        .decode(b64)
+        .map_err(|e| PluginError::InvalidManifest(format!("publisher_key base64: {e}")))?;
+    let bytes: [u8; 32] = raw.try_into().map_err(|v: Vec<u8>| {
+        PluginError::InvalidManifest(format!(
+            "publisher_key must decode to 32 bytes, got {}",
+            v.len()
+        ))
+    })?;
+    VerifyingKey::from_bytes(&bytes)
+        .map_err(|e| PluginError::InvalidManifest(format!("publisher_key not a valid Ed25519 point: {e}")))
+}
+
+/// Decode an `ed25519:<base64>` 64-byte signature.
+fn decode_signature(s: &str) -> Result<Signature, PluginError> {
+    let b64 = s.strip_prefix("ed25519:").ok_or_else(|| {
+        PluginError::InvalidManifest(format!(
+            "wasm_module_sig must be `ed25519:<base64>`, got {s:?}"
+        ))
+    })?;
+    let raw = base64::engine::general_purpose::STANDARD
+        .decode(b64)
+        .map_err(|e| PluginError::InvalidManifest(format!("wasm_module_sig base64: {e}")))?;
+    let bytes: [u8; 64] = raw.try_into().map_err(|v: Vec<u8>| {
+        PluginError::InvalidManifest(format!(
+            "wasm_module_sig must decode to 64 bytes, got {}",
+            v.len()
+        ))
+    })?;
+    Ok(Signature::from_bytes(&bytes))
+}
+
+/// Encode a SHA-256 digest as the manifest `sha256:<hex>` form. Exposed so
+/// tooling (and tests) can produce a manifest hash for real `.wasm` bytes.
+pub fn encode_sha256(wasm_bytes: &[u8]) -> String {
+    format!("sha256:{}", hex::encode(sha256_digest(wasm_bytes)))
+}
+
+/// Encode an Ed25519 verifying key as the manifest `ed25519:<base64>` form.
+pub fn encode_verifying_key(key: &VerifyingKey) -> String {
+    format!(
+        "ed25519:{}",
+        base64::engine::general_purpose::STANDARD.encode(key.to_bytes())
+    )
+}
+
+/// Encode an Ed25519 signature as the manifest `ed25519:<base64>` form.
+pub fn encode_signature(sig: &Signature) -> String {
+    format!(
+        "ed25519:{}",
+        base64::engine::general_purpose::STANDARD.encode(sig.to_bytes())
+    )
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use ed25519_dalek::{Signer, SigningKey};
+
+    /// Deterministic publisher key (mirrors witness_signing's fixed-bytes
+    /// seed convention — DO NOT use in production).
+    fn publisher() -> SigningKey {
+        SigningKey::from_bytes(b"homecore-plugins-pub-test-seed--")
+    }
+
+    fn attacker() -> SigningKey {
+        SigningKey::from_bytes(b"homecore-plugins-attacker-seed--")
+    }
+
+    /// Sign `wasm_bytes` with `key` and produce a manifest carrying the real
+    /// hash + signature + publisher key.
+    fn signed_manifest(wasm_bytes: &[u8], key: &SigningKey) -> PluginManifest {
+        let digest = sha256_digest(wasm_bytes);
+        let sig = key.sign(&digest);
+        PluginManifest {
+            domain: "demo".into(),
+            name: "Demo".into(),
+            version: "1.0.0".into(),
+            documentation: None,
+            iot_class: None,
+            config_flow: false,
+            integration_type: None,
+            dependencies: vec![],
+            requirements: vec![],
+            wasm_module: Some("demo.wasm".into()),
+            wasm_module_hash: Some(encode_sha256(wasm_bytes)),
+            wasm_module_sig: Some(encode_signature(&sig)),
+            publisher_key: Some(encode_verifying_key(&key.verifying_key())),
+            min_homecore_version: None,
+            host_imports_required: vec![],
+            homecore_permissions: vec![],
+            cog_id: None,
+        }
+    }
+
+    #[test]
+    fn valid_sig_from_trusted_key_passes() {
+        let wasm = b"\0asm\x01\0\0\0fake module bytes";
+        let key = publisher();
+        let manifest = signed_manifest(wasm, &key);
+        let policy =
+            PluginPolicy::trusted(&[&encode_verifying_key(&key.verifying_key())]).unwrap();
+        verify_module(&manifest, wasm, &policy).expect("trusted signed module should load");
+    }
+
+    #[test]
+    fn tampered_module_is_rejected() {
+        let wasm = b"\0asm\x01\0\0\0fake module bytes";
+        let key = publisher();
+        let manifest = signed_manifest(wasm, &key);
+        let policy =
+            PluginPolicy::trusted(&[&encode_verifying_key(&key.verifying_key())]).unwrap();
+        // Flip a byte: hash no longer matches.
+        let tampered = b"\0asm\x01\0\0\0FAKE module bytes";
+        let err = verify_module(&manifest, tampered, &policy).unwrap_err();
+        assert!(matches!(err, PluginError::SignatureRejected(_)), "got {err:?}");
+    }
+
+    #[test]
+    fn valid_sig_from_untrusted_key_is_rejected() {
+        let wasm = b"\0asm\x01\0\0\0fake module bytes";
+        // Signed correctly by the attacker, but the attacker is not trusted.
+        let manifest = signed_manifest(wasm, &attacker());
+        let policy =
+            PluginPolicy::trusted(&[&encode_verifying_key(&publisher().verifying_key())]).unwrap();
+        let err = verify_module(&manifest, wasm, &policy).unwrap_err();
+        assert!(matches!(err, PluginError::SignatureRejected(_)), "got {err:?}");
+    }
+
+    #[test]
+    fn forged_signature_is_rejected() {
+        // Manifest claims the trusted publisher_key but the signature was
+        // produced by the attacker (a forged sig under a trusted identity).
+        let wasm = b"\0asm\x01\0\0\0fake module bytes";
+        let digest = sha256_digest(wasm);
+        let forged = attacker().sign(&digest);
+        let mut manifest = signed_manifest(wasm, &publisher());
+        manifest.wasm_module_sig = Some(encode_signature(&forged));
+        let policy =
+            PluginPolicy::trusted(&[&encode_verifying_key(&publisher().verifying_key())]).unwrap();
+        let err = verify_module(&manifest, wasm, &policy).unwrap_err();
+        assert!(matches!(err, PluginError::SignatureRejected(_)), "got {err:?}");
+    }
+
+    #[test]
+    fn unsigned_module_rejected_under_default_policy() {
+        let wasm = b"\0asm\x01\0\0\0unsigned";
+        let manifest = PluginManifest {
+            domain: "u".into(),
+            name: "U".into(),
+            version: "1".into(),
+            documentation: None,
+            iot_class: None,
+            config_flow: false,
+            integration_type: None,
+            dependencies: vec![],
+            requirements: vec![],
+            wasm_module: Some("u.wasm".into()),
+            wasm_module_hash: None,
+            wasm_module_sig: None,
+            publisher_key: None,
+            min_homecore_version: None,
+            host_imports_required: vec![],
+            homecore_permissions: vec![],
+            cog_id: None,
+        };
+        let err = verify_module(&manifest, wasm, &PluginPolicy::deny_all()).unwrap_err();
+        assert!(matches!(err, PluginError::SignatureRejected(_)), "got {err:?}");
+        // ...but AllowUnsigned loads it (with a warn).
+        verify_module(&manifest, wasm, &PluginPolicy::AllowUnsigned)
+            .expect("AllowUnsigned should load an unsigned module");
+    }
+}

v2/crates/homecore-plugins/src/wasmtime_runtime.rs

@@ -30,16 +30,27 @@ use wasmtime::{Engine, Linker, Module, Store};
 
 use crate::error::PluginError;
 use crate::host_abi::{LogLevel, StateChangedEventJson, MAX_ABI_BUFFER_BYTES};
+use crate::manifest::PluginManifest;
+use crate::permissions::PermissionSet;
+use crate::verify::{verify_module, PluginPolicy};
 
 // ── Store data ─────────────────────────────────────────────────────────────
 
 /// Per-plugin state stored inside the Wasmtime [`Store`].
 ///
 /// Wasmtime's `Store<T>` exposes `T` to host functions via `caller.data()`.
-/// We store the `HomeCore` handle and a list of subscribed entity IDs here.
+/// We store the `HomeCore` handle, a list of subscribed entity IDs, and the
+/// plugin's write-permission set (ADR-162 P5 authority isolation).
 pub struct PluginStoreData {
     pub hc: HomeCore,
     pub subscriptions: Vec<String>,
+    /// Entity-write authority distilled from the manifest's
+    /// `homecore_permissions`. Consulted by `hc_state_set`. The
+    /// permission-free [`WasmtimeRuntime::load_wasm`] path installs an
+    /// all-allowing set for backward compatibility; the
+    /// [`WasmtimeRuntime::load_plugin`] path installs the manifest's
+    /// declared set.
+    pub permissions: PermissionSet,
 }
 
 // ── WasmtimeRuntime ────────────────────────────────────────────────────────
@@ -59,14 +70,53 @@ impl WasmtimeRuntime {
         Ok(Self { engine })
     }
 
-    /// Compile and instantiate a WASM plugin from raw bytes.
+    /// Compile and instantiate a WASM plugin from raw bytes, **without**
+    /// signature verification or permission gating (the plugin gets
+    /// all-write authority).
     ///
-    /// Returns a [`WasmPlugin`] handle that owns the `Store` and the
-    /// `Instance`. The handle can be used to call into the WASM module.
+    /// Retained for the legacy/test path and first-party trusted modules.
+    /// Production plugin loading should go through [`Self::load_plugin`],
+    /// which verifies the module (ADR-162 P4) and scopes its write
+    /// authority to the manifest (P5).
     pub fn load_wasm(
         &self,
         wasm_bytes: &[u8],
         hc: HomeCore,
+    ) -> Result<WasmPlugin, PluginError> {
+        self.instantiate(wasm_bytes, hc, PermissionSet::allow_all())
+    }
+
+    /// Verify and instantiate a WASM plugin from its manifest + raw bytes.
+    ///
+    /// This is the secure load path (ADR-162):
+    ///   1. **P4** — [`verify_module`] checks the SHA-256 module hash and
+    ///      Ed25519 signature against the manifest under `policy`. A
+    ///      tampered module, bad/forged signature, untrusted publisher, or
+    ///      (under the secure default) an unsigned module is rejected
+    ///      **before** any guest code runs.
+    ///   2. **P5** — the plugin's `homecore_permissions` are distilled into
+    ///      a [`PermissionSet`] installed in the store, so `hc_state_set`
+    ///      can only write entities the plugin declared.
+    pub fn load_plugin(
+        &self,
+        manifest: &PluginManifest,
+        wasm_bytes: &[u8],
+        hc: HomeCore,
+        policy: &PluginPolicy,
+    ) -> Result<WasmPlugin, PluginError> {
+        // P4: verify before instantiation.
+        verify_module(manifest, wasm_bytes, policy)?;
+        // P5: scope write authority to the manifest's declared permissions.
+        let permissions = PermissionSet::from_manifest(manifest);
+        self.instantiate(wasm_bytes, hc, permissions)
+    }
+
+    /// Shared compile + instantiate, installing the given permission set.
+    fn instantiate(
+        &self,
+        wasm_bytes: &[u8],
+        hc: HomeCore,
+        permissions: PermissionSet,
     ) -> Result<WasmPlugin, PluginError> {
         let module = Module::new(&self.engine, wasm_bytes)
             .map_err(|e| PluginError::RuntimeError(format!("WASM compile: {e}")))?;
@@ -77,6 +127,7 @@ impl WasmtimeRuntime {
         let store_data = PluginStoreData {
             hc,
             subscriptions: Vec::new(),
+            permissions,
         };
         let mut store = Store::new(&self.engine, store_data);
 
@@ -183,7 +234,9 @@ fn register_hc_state_get(
 /// Sets the state for the entity whose UTF-8 ID is at `[eid_ptr,eid_ptr+eid_len)`.
 /// The new state string is at `[state_ptr,state_ptr+state_len)`.
 /// The attributes JSON is at `[attrs_ptr,attrs_ptr+attrs_len)`.
-/// Returns 0 on success, negative on error.
+/// Returns 0 on success, negative on error: -1 (bad memory/args), -2
+/// (invalid entity id), -3 (permission denied — entity not in the
+/// plugin's declared `homecore_permissions`, ADR-162 P5).
 fn register_hc_state_set(
     linker: &mut Linker<PluginStoreData>,
 ) -> Result<(), PluginError> {
@@ -224,6 +277,20 @@ fn register_hc_state_set(
                     Ok(id) => id,
                     Err(_) => return -2,
                 };
+
+                // ── P5 authority isolation (ADR-162) ──────────────────────
+                // Reject a write to an entity the plugin did not declare in
+                // `homecore_permissions`. Return a typed error code to the
+                // guest (-3); do NOT panic the host.
+                if !caller.data().permissions.may_write(entity_id.as_str()) {
+                    eprintln!(
+                        "[PLUGIN WARN] denied hc_state_set on `{}` — not in plugin's declared \
+                         homecore_permissions (P5 authority isolation)",
+                        entity_id.as_str()
+                    );
+                    return -3;
+                }
+
                 let attrs: serde_json::Value =
                     serde_json::from_str(&attrs_str).unwrap_or(serde_json::json!({}));
 

v2/crates/homecore-plugins/tests/integration.rs

@@ -371,4 +371,259 @@ mod wasmtime_tests {
         let r = plugin.call_setup("{}").expect("setup");
         assert_eq!(r, 0);
     }
+
+    // ── ADR-162 P4: signature/integrity verification ────────────────────────
+    //
+    // Each of these FAILS on the pre-ADR-162 code, which had no
+    // `load_plugin` / `verify_module` at all — the manifest hash/sig/key
+    // were parsed and discarded. They drive the real verification gate.
+
+    use ed25519_dalek::{Signer, SigningKey};
+    use homecore_plugins::manifest::PluginManifest;
+    use homecore_plugins::verify::{encode_sha256, encode_signature, encode_verifying_key};
+    use homecore_plugins::PluginPolicy;
+
+    /// Deterministic publisher key (fixed seed — never use in production;
+    /// mirrors the cog-ha-matter witness_signing test-key convention).
+    fn publisher_key() -> SigningKey {
+        SigningKey::from_bytes(b"hc-plugins-integration-pub-seed-")
+    }
+
+    fn untrusted_key() -> SigningKey {
+        SigningKey::from_bytes(b"hc-plugins-integration-evil-seed")
+    }
+
+    /// A minimal valid module that writes `light.kitchen` on setup, plus a
+    /// `light.*` permission grant. Returns the WAT source.
+    const WRITE_LIGHT_WAT: &str = r#"
+(module
+  (import "env" "hc_state_get"       (func $hc_state_get (param i32 i32 i32 i32) (result i32)))
+  (import "env" "hc_state_set"       (func $hc_state_set (param i32 i32 i32 i32 i32 i32) (result i32)))
+  (import "env" "hc_state_subscribe" (func $hc_state_subscribe (param i32 i32) (result i32)))
+  (import "env" "hc_log"             (func $hc_log (param i32 i32 i32)))
+  (memory (export "memory") 1)
+  (global $bump (mut i32) (i32.const 512))
+  (data (i32.const 0)   "light.kitchen")
+  (data (i32.const 64)  "on")
+  (data (i32.const 128) "{}")
+  (func (export "alloc") (param i32) (result i32)
+    (local $p i32)
+    (local.set $p (global.get $bump))
+    (global.set $bump (i32.add (global.get $bump) (local.get 0)))
+    (local.get $p))
+  (func (export "dealloc") (param i32 i32))
+  (func (export "plugin_setup") (param i32 i32) (result i32)
+    (call $hc_state_set
+      (i32.const 0) (i32.const 13)   ;; "light.kitchen"
+      (i32.const 64) (i32.const 2)   ;; "on"
+      (i32.const 128) (i32.const 2)) ;; "{}"
+    drop
+    (i32.const 0))
+  (func (export "plugin_handle_state_changed") (param i32 i32) (result i32) (i32.const 0))
+)
+"#;
+
+    /// Build a manifest signed by `key` over the SHA-256 of `wasm_bytes`,
+    /// with the given write-permission grants.
+    fn signed_manifest(
+        wasm_bytes: &[u8],
+        key: &SigningKey,
+        perms: &[&str],
+    ) -> PluginManifest {
+        use sha2::{Digest, Sha256};
+        let digest: [u8; 32] = Sha256::digest(wasm_bytes).into();
+        let sig = key.sign(&digest);
+        let mut m = PluginManifest::parse_json(
+            r#"{"domain":"demo","name":"Demo","version":"1.0.0"}"#,
+        )
+        .unwrap();
+        m.wasm_module = Some("demo.wasm".into());
+        m.wasm_module_hash = Some(encode_sha256(wasm_bytes));
+        m.wasm_module_sig = Some(encode_signature(&sig));
+        m.publisher_key = Some(encode_verifying_key(&key.verifying_key()));
+        m.homecore_permissions = perms.iter().map(|s| s.to_string()).collect();
+        m
+    }
+
+    #[test]
+    fn p4_valid_sig_from_trusted_key_loads() {
+        let wasm = wat::parse_str(WRITE_LIGHT_WAT).expect("WAT");
+        let key = publisher_key();
+        let manifest = signed_manifest(&wasm, &key, &["light.*"]);
+        let policy =
+            PluginPolicy::trusted(&[&encode_verifying_key(&key.verifying_key())]).unwrap();
+
+        let rt = WasmtimeRuntime::new().expect("rt");
+        let hc = HomeCore::new();
+        rt.load_plugin(&manifest, &wasm, hc, &policy)
+            .expect("a validly-signed, trusted plugin must load");
+    }
+
+    #[test]
+    fn p4_tampered_module_is_rejected() {
+        let wasm = wat::parse_str(WRITE_LIGHT_WAT).expect("WAT");
+        let key = publisher_key();
+        // Manifest signs the original bytes; we then load DIFFERENT bytes.
+        let manifest = signed_manifest(&wasm, &key, &["light.*"]);
+        let policy =
+            PluginPolicy::trusted(&[&encode_verifying_key(&key.verifying_key())]).unwrap();
+
+        // Re-compile a byte-different module (writes "off" not "on").
+        let tampered_src = WRITE_LIGHT_WAT.replace(r#""on""#, r#""of""#);
+        let tampered = wat::parse_str(&tampered_src).expect("WAT");
+        assert_ne!(wasm, tampered, "test bug: bytes must differ");
+
+        let rt = WasmtimeRuntime::new().expect("rt");
+        let hc = HomeCore::new();
+        match rt.load_plugin(&manifest, &tampered, hc, &policy) {
+            Err(homecore_plugins::PluginError::SignatureRejected(_)) => {}
+            Ok(_) => panic!("tampered module must be rejected (hash mismatch), but it loaded"),
+            Err(e) => panic!("expected SignatureRejected, got {e:?}"),
+        }
+    }
+
+    #[test]
+    fn p4_valid_sig_from_untrusted_key_is_rejected() {
+        let wasm = wat::parse_str(WRITE_LIGHT_WAT).expect("WAT");
+        // Correctly signed by the untrusted key — but it is not on the allowlist.
+        let manifest = signed_manifest(&wasm, &untrusted_key(), &["light.*"]);
+        let policy =
+            PluginPolicy::trusted(&[&encode_verifying_key(&publisher_key().verifying_key())])
+                .unwrap();
+
+        let rt = WasmtimeRuntime::new().expect("rt");
+        let hc = HomeCore::new();
+        match rt.load_plugin(&manifest, &wasm, hc, &policy) {
+            Err(homecore_plugins::PluginError::SignatureRejected(_)) => {}
+            Ok(_) => panic!("untrusted publisher must be rejected, but it loaded"),
+            Err(e) => panic!("expected SignatureRejected, got {e:?}"),
+        }
+    }
+
+    #[test]
+    fn p4_unsigned_module_rejected_by_default_loads_only_under_allow_unsigned() {
+        let wasm = wat::parse_str(WRITE_LIGHT_WAT).expect("WAT");
+        let mut manifest = PluginManifest::parse_json(
+            r#"{"domain":"u","name":"U","version":"1"}"#,
+        )
+        .unwrap();
+        manifest.wasm_module = Some("u.wasm".into());
+        manifest.homecore_permissions = vec!["light.*".into()];
+        // No hash/sig/key → unsigned.
+
+        let rt = WasmtimeRuntime::new().expect("rt");
+        // Secure default: rejected.
+        match rt.load_plugin(&manifest, &wasm, HomeCore::new(), &PluginPolicy::deny_all()) {
+            Err(homecore_plugins::PluginError::SignatureRejected(_)) => {}
+            Ok(_) => panic!("unsigned module must be rejected under the secure default"),
+            Err(e) => panic!("expected SignatureRejected, got {e:?}"),
+        }
+        // Dev escape hatch: loads (with a loud warn).
+        rt.load_plugin(
+            &manifest,
+            &wasm,
+            HomeCore::new(),
+            &PluginPolicy::AllowUnsigned,
+        )
+        .expect("AllowUnsigned dev policy must load an unsigned module");
+    }
+
+    // ── ADR-162 P5: authority / capability isolation ────────────────────────
+    //
+    // FAILS on the pre-ADR-162 code, where `hc_state_set` ignored
+    // `homecore_permissions` entirely and let any plugin write any entity.
+
+    /// Module that writes `lock.front_door` on setup (an over-privileged
+    /// write a `light.*` plugin must NOT be allowed to perform).
+    const WRITE_LOCK_WAT: &str = r#"
+(module
+  (import "env" "hc_state_get"       (func $hc_state_get (param i32 i32 i32 i32) (result i32)))
+  (import "env" "hc_state_set"       (func $hc_state_set (param i32 i32 i32 i32 i32 i32) (result i32)))
+  (import "env" "hc_state_subscribe" (func $hc_state_subscribe (param i32 i32) (result i32)))
+  (import "env" "hc_log"             (func $hc_log (param i32 i32 i32)))
+  (memory (export "memory") 1)
+  (global $bump (mut i32) (i32.const 512))
+  (data (i32.const 0)   "lock.front_door")
+  (data (i32.const 64)  "unlocked")
+  (data (i32.const 128) "{}")
+  (func (export "alloc") (param i32) (result i32)
+    (local $p i32)
+    (local.set $p (global.get $bump))
+    (global.set $bump (i32.add (global.get $bump) (local.get 0)))
+    (local.get $p))
+  (func (export "dealloc") (param i32 i32))
+  ;; plugin_setup returns the hc_state_set result code so the host test can
+  ;; assert the guest saw the typed permission-denied error (-3).
+  (func (export "plugin_setup") (param i32 i32) (result i32)
+    (call $hc_state_set
+      (i32.const 0) (i32.const 15)   ;; "lock.front_door"
+      (i32.const 64) (i32.const 8)   ;; "unlocked"
+      (i32.const 128) (i32.const 2))) ;; "{}"
+  (func (export "plugin_handle_state_changed") (param i32 i32) (result i32) (i32.const 0))
+)
+"#;
+
+    #[test]
+    fn p5_declared_light_plugin_may_write_light_but_not_lock() {
+        let key = publisher_key();
+        let trusted = PluginPolicy::trusted(&[&encode_verifying_key(&key.verifying_key())]).unwrap();
+        let rt = WasmtimeRuntime::new().expect("rt");
+
+        // (a) A `light.*` plugin writing `light.kitchen` → ALLOWED.
+        let light_wasm = wat::parse_str(WRITE_LIGHT_WAT).expect("WAT");
+        let light_manifest = signed_manifest(&light_wasm, &key, &["light.*"]);
+        let hc_a = HomeCore::new();
+        let plugin_a = rt
+            .load_plugin(&light_manifest, &light_wasm, hc_a.clone(), &trusted)
+            .expect("light plugin loads");
+        let r = plugin_a.call_setup("{}").expect("setup");
+        assert_eq!(r, 0, "write to declared light.kitchen should succeed");
+        let kitchen = homecore::EntityId::parse("light.kitchen").unwrap();
+        assert_eq!(
+            hc_a.states().get(&kitchen).expect("light.kitchen written").state,
+            "on"
+        );
+
+        // (b) The SAME `light.*` plugin attempting to write `lock.front_door`
+        // → REJECTED with the typed -3 code, and the lock is NOT written.
+        let lock_wasm = wat::parse_str(WRITE_LOCK_WAT).expect("WAT");
+        let lock_manifest = signed_manifest(&lock_wasm, &key, &["light.*"]);
+        let hc_b = HomeCore::new();
+        let plugin_b = rt
+            .load_plugin(&lock_manifest, &lock_wasm, hc_b.clone(), &trusted)
+            .expect("module loads (verification ok); the WRITE is what's gated");
+        let denied = plugin_b.call_setup("{}").expect("setup runs without trapping host");
+        assert_eq!(
+            denied, -3,
+            "over-privileged write to lock.front_door must return -3 (permission denied)"
+        );
+        let lock = homecore::EntityId::parse("lock.front_door").unwrap();
+        assert!(
+            hc_b.states().get(&lock).is_none(),
+            "lock.front_door must NOT have been written by a light-only plugin"
+        );
+    }
+
+    #[test]
+    fn p5_plugin_with_no_permissions_can_write_nothing() {
+        let key = publisher_key();
+        let trusted = PluginPolicy::trusted(&[&encode_verifying_key(&key.verifying_key())]).unwrap();
+        let rt = WasmtimeRuntime::new().expect("rt");
+
+        let wasm = wat::parse_str(WRITE_LIGHT_WAT).expect("WAT");
+        // No permissions declared at all.
+        let manifest = signed_manifest(&wasm, &key, &[]);
+        let hc = HomeCore::new();
+        let plugin = rt
+            .load_plugin(&manifest, &wasm, hc.clone(), &trusted)
+            .expect("module loads; the write is gated");
+        // WRITE_LIGHT_WAT drops the host-import result and returns 0, so we
+        // assert the denial via the side-effect: the write must NOT land.
+        plugin.call_setup("{}").expect("setup runs without trapping host");
+        let kitchen = homecore::EntityId::parse("light.kitchen").unwrap();
+        assert!(
+            hc.states().get(&kitchen).is_none(),
+            "no-permission plugin must not write light.kitchen (P5 authority isolation)"
+        );
+    }
 }