Add height zones, jetpack boost particles, and TigerStyle guidelines

Level generator: add vertical variety with tall levels (46 tiles).
Segment generators accept ground_row parameter, SEG_CLIMB connects
height zones, transitions inherit predecessor ground row to prevent
walkability gaps. Climb segments respect traversal direction.

Jetpack boost: add blue flame particles during dash (burst + trail)
and continuous idle glow from player back while boost timer is active.

Camera: add 30px vertical look-ahead when player velocity exceeds
50 px/s.

Fix flame vent pedestal in gen_pit to use ground-relative position
instead of map bottom (broken in tall HIGH-zone levels).

Add TigerStyle coding guidelines to AGENTS.md adapted for C11.
Add tall_test.lvl (40x46) for height zone validation.

AGENTS.md

@@ -129,6 +129,100 @@ Paths are forward-slash, relative to `src/` or `include/`: `"engine/core.h"`, `"
 - `snprintf` / `strncpy` with explicit size limits for strings
 - `ASSET_PATH_MAX` (256) for path buffers
 
+## TigerStyle Guidelines
+
+Follow the principles from [TigerStyle](https://github.com/tigerbeetle/tigerbeetle/blob/main/docs/TIGER_STYLE.md),
+adapted for this C11 codebase. The design goals are **safety, performance, and developer
+experience**, in that order.
+
+### Safety
+
+- **Simple, explicit control flow.** No recursion. Minimal abstractions — only where they
+  genuinely model the domain. Every abstraction has a cost; prefer straightforward code.
+
+- **Put a limit on everything.** All loops and queues must have a fixed upper bound. Use
+  `MAX_ENTITIES`, `MAX_ENTITY_SPAWNS`, `MAX_EXIT_ZONES`, etc. Where a loop cannot terminate
+  (e.g. the game loop), document why.
+
+- **Assert preconditions, postconditions, and invariants.** Validate function arguments and
+  return values. A function must not operate blindly on unchecked data. In C, use `assert()`
+  or early-return checks with `fprintf(stderr, ...)` for runtime-recoverable cases.
+  Split compound conditions: prefer `assert(a); assert(b);` over `assert(a && b);`.
+
+- **Assert the positive and negative space.** Check what you expect AND what you do not expect.
+  Bugs live at the boundary between valid and invalid data.
+
+- **Static allocation after initialization.** Fixed-size arrays for collections (`MAX_ENTITIES`
+  pool, tile defs). Dynamic allocation (`calloc`) only during level loading for tile layers.
+  No allocation or reallocation during gameplay.
+
+- **Smallest possible scope for variables.** Declare variables close to where they are used.
+  Minimize the number of live variables at any point.
+
+- **Hard limit of ~70 lines per function.** When splitting, centralize control flow (switch/if)
+  in the parent function and push pure computation into helpers. Keep leaf functions pure.
+  "Push `if`s up and `for`s down."
+
+- **Zero compiler warnings.** All builds must pass `-Wall -Wextra` with zero warnings.
+
+- **Handle all errors.** Every `fopen`, `calloc`, `snprintf` return must be checked. Early
+  return on failure.
+
+### Performance
+
+- **Think about performance in the design phase.** The biggest wins (1000x) come from
+  structural decisions, not micro-optimization after the fact.
+
+- **Back-of-the-envelope sketches** for the four resources: network, disk, memory, CPU.
+  For a game: frame budget is ~16ms at 60 Hz. Know where time goes.
+
+- **Optimize for the slowest resource first** (disk > memory > CPU), weighted by frequency.
+  A cache miss that happens every frame matters more than a disk read that happens once at
+  level load.
+
+- **Batch and amortize.** Sprite batching via `renderer_submit()`. Particle pools. Tile
+  culling to the viewport. Don't iterate what you don't need to.
+
+- **Be explicit with the compiler.** Don't rely on the optimizer to fix structural problems.
+  Extract hot inner loops into standalone helpers with primitive arguments when it helps
+  clarity and performance.
+
+### Developer Experience
+
+- **Get the nouns and verbs right.** Names should capture what a thing is or does. Take time
+  to find the right name. Module-prefixed functions (`player_update`, `tilemap_load`) already
+  enforce this.
+
+- **Add units or qualifiers last, sorted by descending significance.** For example,
+  `latency_ms_max` not `max_latency_ms`. Related variables then align: `latency_ms_min`,
+  `latency_ms_avg`.
+
+- **Always say why.** Comments explain rationale, not just what the code does. If a design
+  decision isn't obvious, explain the tradeoff. Code alone is not documentation.
+
+- **Comments are sentences.** Capital letter, full stop, space after `/*`. End-of-line
+  comments can be phrases without punctuation.
+
+- **Order matters for readability.** Put important things near the top of a file. Public API
+  first, then helpers. In structs, fields before methods.
+
+- **Don't duplicate variables or alias them.** One source of truth per value. Reduces the
+  chance of state getting out of sync.
+
+- **Calculate or check variables close to where they are used.** Don't introduce variables
+  before they are needed. Minimize the gap between place-of-check and place-of-use.
+
+- **Descriptive commit messages.** Imperative mood. Inform the reader about the why, not
+  just the what. The commit message is the permanent record — PR descriptions are not
+  stored in git.
+
+### Zero Technical Debt
+
+Do it right the first time. Don't allow known issues to slip through — exponential-complexity
+algorithms, unbounded loops, potential buffer overflows. What we ship is solid. We may lack
+features, but what we have meets our design goals. This is the only way to make steady
+incremental progress.
+
 ## Architecture Patterns
 
 ### Entity System

TODO.md

@@ -41,29 +41,23 @@ Implemented: 3 moon levels connected by spacecraft takeoff/landing sequences.
   intro, 5 asteroids, unarmed until gun powerup near exit. Exit to level01.
 - **level01.lvl** — Space station with spacecraft landing intro (arriving from moon).
 
-## Level generator: height zones (verticality)
+## ~~Level generator: height zones (verticality)~~ ✓
-Add vertical variety to generated levels using a "height zones" approach:
+Implemented: tall level support (46 tiles, two screens) with height zones.
-- Double tilemap height from 23 to ~46 tiles (two screens tall)
+- Camera vertical look-ahead (30px lead when player moves vertically > 50 px/s)
-- Define two elevation bands: HIGH (ground ~row 17) and LOW (ground ~row 40)
+- All segment generators (`gen_flat`, `gen_pit`, `gen_platforms`, `gen_corridor`,
-- Existing segment generators get a `y_offset` parameter so internal logic
+  `gen_arena`, `gen_shaft`, `gen_transition`) accept `ground_row` parameter —
-  barely changes — platforms, enemies, corridors all shift by offset
+  platforms, enemies, and hazards are placed relative to the zone's ground level
-- New vertical connector segments (ramps/climbs) bridge between zones
+- `SEG_CLIMB` connector segment type: vertical shaft with alternating platforms,
-- Theme decides zone usage: Surface stays LOW, Station uses both, Base uses HIGH
+  wall openings, optional moving platform and enemies, bridges height zones
-- Camera needs vertical look-ahead when player has vertical velocity
+- `levelgen_generate()` assigns zones per theme: Surface → LOW (row 43),
+  Base → HIGH (row 17), Station → alternates. `SEG_CLIMB` auto-inserted at
+  zone boundaries. Single-theme levels stay at standard 23-tile height.
+- Station generator unchanged (23 tiles, corridor envelope constrains)
+- Tall test level: `assets/levels/tall_test.lvl` (40x46)
 
-### Implementation steps
+## ~~Jetpack boost blue flame effects~~ ✓
-1. Add vertical camera look-ahead (small Y lead when player moves vertically)
+Implemented: `particle_emit_jetpack_boost_burst()` (electric blue core +
-2. Create a handcrafted tall test level (~40x46) to validate camera, physics,
+blue-white flare, 18 particles mixed into regular burst) and
-   rendering, and entities all work with vertical scrolling
+`particle_emit_jetpack_boost_trail()` (blue sparks + pale blue wisps,
-3. Refactor `set_tile()` / `fill_ground()` to accept a height parameter instead
+3 particles/frame). Both activate only when `jetpack_boost_timer > 0`.
-   of hardcoded `SEG_HEIGHT`
+Burst fires on dash start, trail emits each frame during dash.
-4. Add `y_offset` parameter to all segment generators
-5. Add `SEG_CLIMB` connector segment type (shaft/platforms between zones)
-6. Update `levelgen_generate()` to assign zones per segment and insert climbs
-7. The station generator stays at 23 tiles (corridor envelope already constrains)
-
-## Jetpack boost blue flame effects
-- Add continuous blue flame particles trailing from the player during jetpack
-  boost (while boost is active, not just on burst)
-- Add blue accents to the jetpack burst effect itself — mix blue flame particles
-  into the existing yellow/orange exhaust plume

assets/levels/tall_test.lvl

@@ -0,0 +1,87 @@
+# Tall Test Level - Height Zones Validation
+# ==========================================
+# 46 tiles tall (two screens). Tests vertical scrolling,
+# camera look-ahead, and climbing between height zones.
+
+TILESET assets/tiles/tileset.png
+SIZE 40 46
+SPAWN 4 15
+GRAVITY 600
+BG_COLOR 10 14 22
+MUSIC assets/sounds/algardalgar.ogg
+
+# Enemies - high zone
+ENTITY grunt 10 16
+ENTITY flyer 8 8
+
+# Enemies - low zone
+ENTITY grunt 28 42
+ENTITY grunt 34 42
+ENTITY flyer 30 34
+ENTITY turret 25 35
+
+# Enemies - shaft
+ENTITY flyer 18 28
+
+# Powerups
+ENTITY powerup_hp 13 12
+ENTITY powerup_jet 18 20
+ENTITY powerup_hp 32 38
+
+# Exit zone at far right bottom
+EXIT 36 40 2 3 assets/levels/level01.lvl
+
+# Tile definitions
+TILEDEF 1 0 0 1
+TILEDEF 2 1 0 1
+TILEDEF 3 2 0 1
+TILEDEF 4 0 1 2
+
+# Collision layer (40 wide x 46 tall)
+LAYER collision
+1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+1 1 0 0 0 4 4 4 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+1 1 0 0 0 0 0 0 0 0 0 0 4 4 4 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 4 4 4 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 4 4 4 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1
+0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1
+0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1
+0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1
+0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 4 4 4 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1
+0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1
+0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1
+0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1
+0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 4 4 4 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1
+0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1
+0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 1 1 0 0 4 4 4 4 0 0 0 0 0 0 0 0 0 1 1
+0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1
+0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 4 4 4 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1
+0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 4 4 4 4 0 0 0 1 1
+0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1
+0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1
+0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1
+0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
+0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
+0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

src/engine/camera.c

@@ -9,7 +9,7 @@ void camera_init(Camera *c, float vp_w, float vp_h) {
     c->bounds_max = vec2(vp_w, vp_h); /* default: one screen */
     c->smoothing = 5.0f;
     c->deadzone = vec2(30.0f, 20.0f);
-    c->look_ahead = vec2(40.0f, 0.0f);
+    c->look_ahead = vec2(40.0f, 30.0f);
     c->zoom = 1.0f;
 }
 
@@ -28,6 +28,10 @@ void camera_follow(Camera *c, Vec2 target, Vec2 velocity, float dt) {
     if (velocity.x > 10.0f)       desired.x += c->look_ahead.x;
     else if (velocity.x < -10.0f) desired.x -= c->look_ahead.x;
 
+    /* Vertical look-ahead: lead camera when falling or rising */
+    if (velocity.y > 50.0f)       desired.y += c->look_ahead.y;
+    else if (velocity.y < -50.0f) desired.y -= c->look_ahead.y;
+
     /* Smooth follow using exponential decay */
     float t = 1.0f - expf(-c->smoothing * dt);
     c->pos = vec2_lerp(c->pos, desired, t);

src/engine/particle.c

@@ -301,6 +301,137 @@ void particle_emit_jetpack_trail(Vec2 pos, Vec2 dash_dir) {
     particle_emit(&smoke);
 }
 
+void particle_emit_jetpack_boost_burst(Vec2 pos, Vec2 dash_dir) {
+    /* Blue flame accents mixed into the regular jetpack burst */
+    float exhaust_angle = atan2f(-dash_dir.y, -dash_dir.x);
+
+    /* Hot blue core — bright electric blue */
+    ParticleBurst core = {
+        .origin    = pos,
+        .count     = 10,
+        .speed_min = 90.0f,
+        .speed_max = 220.0f,
+        .life_min  = 0.15f,
+        .life_max  = 0.35f,
+        .size_min  = 2.0f,
+        .size_max  = 4.5f,
+        .spread    = 0.4f,
+        .direction = exhaust_angle,
+        .drag      = 2.5f,
+        .gravity_scale = 0.05f,
+        .color     = {80, 160, 255, 255},   /* electric blue */
+        .color_vary = true,
+    };
+    particle_emit(&core);
+
+    /* Outer blue-white flare */
+    ParticleBurst flare = {
+        .origin    = pos,
+        .count     = 8,
+        .speed_min = 40.0f,
+        .speed_max = 130.0f,
+        .life_min  = 0.2f,
+        .life_max  = 0.4f,
+        .size_min  = 1.5f,
+        .size_max  = 3.0f,
+        .spread    = 0.7f,
+        .direction = exhaust_angle,
+        .drag      = 3.0f,
+        .gravity_scale = 0.1f,
+        .color     = {140, 200, 255, 255},  /* light blue */
+        .color_vary = true,
+    };
+    particle_emit(&flare);
+}
+
+void particle_emit_jetpack_boost_trail(Vec2 pos, Vec2 dash_dir) {
+    /* Continuous blue flame trail while dashing with boost active */
+    float exhaust_angle = atan2f(-dash_dir.y, -dash_dir.x);
+
+    /* Blue flame sparks */
+    ParticleBurst sparks = {
+        .origin    = pos,
+        .count     = 2,
+        .speed_min = 50.0f,
+        .speed_max = 140.0f,
+        .life_min  = 0.1f,
+        .life_max  = 0.25f,
+        .size_min  = 1.5f,
+        .size_max  = 3.0f,
+        .spread    = 0.35f,
+        .direction = exhaust_angle,
+        .drag      = 3.0f,
+        .gravity_scale = 0.05f,
+        .color     = {60, 140, 255, 255},   /* bright blue */
+        .color_vary = true,
+    };
+    particle_emit(&sparks);
+
+    /* Blue-white wisps */
+    ParticleBurst wisps = {
+        .origin    = pos,
+        .count     = 1,
+        .speed_min = 20.0f,
+        .speed_max = 50.0f,
+        .life_min  = 0.15f,
+        .life_max  = 0.35f,
+        .size_min  = 2.0f,
+        .size_max  = 3.5f,
+        .spread    = 0.5f,
+        .direction = exhaust_angle,
+        .drag      = 3.5f,
+        .gravity_scale = -0.05f,
+        .color     = {160, 210, 255, 200},  /* pale blue */
+        .color_vary = true,
+    };
+    particle_emit(&wisps);
+}
+
+void particle_emit_jetpack_boost_idle(Vec2 pos, bool facing_left) {
+    /* Ambient blue flame simmering from the player's back while boost is
+     * active but the player isn't dashing. Exhaust drifts backward and
+     * slightly downward — a subtle idle glow effect. */
+    float exhaust_angle = facing_left ? 0.0f : (float)M_PI; /* away from facing */
+
+    /* Small blue sparks drifting backward */
+    ParticleBurst sparks = {
+        .origin    = pos,
+        .count     = 1,
+        .speed_min = 15.0f,
+        .speed_max = 45.0f,
+        .life_min  = 0.12f,
+        .life_max  = 0.3f,
+        .size_min  = 1.0f,
+        .size_max  = 2.5f,
+        .spread    = 0.8f,
+        .direction = exhaust_angle,
+        .drag      = 4.0f,
+        .gravity_scale = 0.15f,
+        .color     = {50, 130, 255, 220},   /* medium blue */
+        .color_vary = true,
+    };
+    particle_emit(&sparks);
+
+    /* Faint blue-white wisps floating up */
+    ParticleBurst wisps = {
+        .origin    = pos,
+        .count     = 1,
+        .speed_min = 8.0f,
+        .speed_max = 25.0f,
+        .life_min  = 0.15f,
+        .life_max  = 0.35f,
+        .size_min  = 1.5f,
+        .size_max  = 2.5f,
+        .spread    = 1.0f,
+        .direction = exhaust_angle - 0.3f,  /* slightly upward */
+        .drag      = 4.5f,
+        .gravity_scale = -0.1f,
+        .color     = {140, 200, 255, 160},  /* pale blue, translucent */
+        .color_vary = true,
+    };
+    particle_emit(&wisps);
+}
+
 void particle_emit_muzzle_flash(Vec2 pos, Vec2 shoot_dir) {
     float angle = atan2f(shoot_dir.y, shoot_dir.x);
 

src/engine/particle.h

@@ -73,6 +73,16 @@ void particle_emit_jetpack_burst(Vec2 pos, Vec2 dash_dir);
 /* Jetpack exhaust trail (call each frame while dashing) */
 void particle_emit_jetpack_trail(Vec2 pos, Vec2 dash_dir);
 
+/* Blue flame burst (mixed into jetpack burst when boost is active) */
+void particle_emit_jetpack_boost_burst(Vec2 pos, Vec2 dash_dir);
+
+/* Continuous blue flame trail during jetpack boost (call each frame while dashing + boosted) */
+void particle_emit_jetpack_boost_trail(Vec2 pos, Vec2 dash_dir);
+
+/* Ambient blue glow from jetpack while boost is active but not dashing
+ * (call each frame; facing_left determines exhaust side) */
+void particle_emit_jetpack_boost_idle(Vec2 pos, bool facing_left);
+
 /* Muzzle flash (short bright burst in shoot direction) */
 void particle_emit_muzzle_flash(Vec2 pos, Vec2 shoot_dir);
 

src/game/player.c

@@ -288,6 +288,11 @@ void player_update(Entity *self, float dt, const Tilemap *map) {
         );
         particle_emit_jetpack_trail(exhaust_pos, pd->dash_dir);
 
+        /* Blue flame trail when boost is active */
+        if (pd->jetpack_boost_timer > 0) {
+            particle_emit_jetpack_boost_trail(exhaust_pos, pd->dash_dir);
+        }
+
         /* Skip normal movement during dash */
         physics_update(body, dt, map);
         animation_update(&self->anim, dt);
@@ -330,10 +335,28 @@ void player_update(Entity *self, float dt, const Tilemap *map) {
         );
         particle_emit_jetpack_burst(exhaust_pos, pd->dash_dir);
 
+        /* Blue flame accents when boost powerup is active */
+        if (pd->jetpack_boost_timer > 0) {
+            particle_emit_jetpack_boost_burst(exhaust_pos, pd->dash_dir);
+        }
+
         audio_play_sound(s_sfx_dash, 96);
         return;
     }
 
+    /* ── Jetpack boost idle glow ─────────────── */
+    /* Ambient blue flame from the player's back while boost is active
+     * and not dashing. Emits from the rear center of the sprite. */
+    if (pd->jetpack_boost_timer > 0) {
+        bool facing_left = (self->flags & ENTITY_FACING_LEFT) != 0;
+        Vec2 back_pos = vec2(
+            facing_left ? body->pos.x + body->size.x - 1.0f
+                        : body->pos.x + 1.0f,
+            body->pos.y + body->size.y * 0.45f
+        );
+        particle_emit_jetpack_boost_idle(back_pos, facing_left);
+    }
+
     /* ── Horizontal movement ─────────────────── */
     float target_vx = 0.0f;
     if (hold_left)  target_vx -= PLAYER_SPEED;