diff --git a/README.md b/README.md
index 3750428..389238a 100644
--- a/README.md
+++ b/README.md
@@ -7,10 +7,10 @@ puppet control model: leg orientation decoupled from body via procedural
 callback, foot-body-orientation ("tactical twist"), scale-deformation walk
 cycle, and inheritance-decoupled foot sprites.
 
-**Version:** 0.4.3
+**Version:** 0.4.4
 **Module-ID:** vagrant-skeleton
-**Requires:** lib-core.input >=0.4.0, lib-core.camera >=0.3.0, lib-core.render >=0.1.0, lib-core.maps >=0.1.2, lib-core.puppet >=0.4.3, lib-asset.prototype-subterrain >=0.1.0
-**Tags:** test-chamber, puppet, walking-sim
+**Requires:** lib-core.input >=0.4.0, lib-core.camera >=0.3.0, lib-core.render >=0.1.0, lib-core.maps >=0.1.2, lib-core.puppet >=0.4.4, lib-core.interaction >=0.1.0, lib-asset.prototype-subterrain >=0.1.0
+**Tags:** test-chamber, puppet, walking-sim, interaction
 
 ## Topology
 
@@ -20,7 +20,9 @@ cycle, and inheritance-decoupled foot sprites.
 ## Controls
 
 - **W A S D** — direct movement (4-way, normalized for diagonals)
+- **Shift + WASD** — sprint (2x player speed + 2x walk-anim cadence)
 - **Mouse** — body + head look-at targets (same position, different smoothing)
+- **E** — interact with nearest proximity-trigger in range
 - **ESC** — return to launcher
 
 ## Demonstrates
@@ -34,16 +36,23 @@ cycle, and inheritance-decoupled foot sprites.
   - Per-channel conflict guard: walk animation (scl) + procedural (rot) on same leg bones
   - Camera in `camera.begin()/finish()` block for correct world-space rendering
 - WASD movement → walk_fwd_lower + walk_upper animation pair (speed = 0.45x)
+- Shift+WASD sprint → `puppet.set_play_speed` doubles cadence to 0.9x mid-cycle
+  (no animation restart on toggle); player movement speed doubled (120 → 240)
 - Idle state → idle + idle_lower animations
 - Camera-chase via lib-core.camera target-provider
 - Sprite-tilemap via lib-core.maps
+- lib-core.interaction proximity trigger on the backpack sprite at (350, 400),
+  range 40px, "interact" action bound to E — fires log on dispatch
 
 ## Interactions
 
 - WASD active → legs swing in walk direction; body slowly rotates to mouse; head snaps to mouse
+- Shift held while moving → 2x player speed; walk cadence doubles (smooth mid-cycle transition)
 - WASD released → idle_lower collapses legs (scl=0); upper body returns to idle sway
 - Mouse moved → body lazy-rotates via slerp (look_at_slerp: 6); head snaps within ±60° of body
 - Walking east while body faces north → legs perpendicular to body, hips body-relative, feet face north
+- E pressed within 40px of the backpack sprite → fires `"interact"` action;
+  callback logs `vagrant: interact with backpack (distance=X.X)`
 
 ## CI Hooks
 
@@ -66,6 +75,15 @@ cycle, and inheritance-decoupled foot sprites.
 
 ## CHANGELOG
 
+### v0.4.4
+- **Sprint** (Shift+WASD): doubles `WALK_SPEED` (120 → 240) and walk-anim
+  `speed` (0.45 → 0.9). Mid-walk sprint toggle uses `puppet.set_play_speed`
+  (new v0.4.4 API) — no animation cycle restart.
+- **Backpack interaction**: `lib-core.interaction.register(350, 400, 40,
+  "interact", callback)` registered at init. Pressing E within range
+  prints log message via `engine.print` with actor distance.
+- New deps: lib-core.interaction ^0.1.0. lib-core.puppet bumped to >=0.4.4.
+
 ### v0.4.3
 - `inherit_scale: false` on foot_l, foot_r: feet no longer Y-flip when leg.scl_y
   inverts during walk cycle. foot.rest.scl reset to [1,1].