docs: add docs/ISSUES.md tactical issue tracker + CLAUDE.md rules

Introduces `docs/ISSUES.md` as the tactical rolling list of known bugs +
small deferred features. Scope is strict: anything fitting in one-to-two
commits lives here; anything larger gets promoted to a Phase in the
roadmap. Complement, not replacement, of the strategic roadmap.

Schema per issue:
- Sequential integer ID (#1, #2, ...)
- Status (OPEN / IN-PROGRESS / DONE)
- Severity (HIGH / MEDIUM / LOW)
- Filed date, component, description, root cause, files, research,
  acceptance
- DONE items move to "Recently closed" at the bottom with commit SHA

Four seeded issues from the 2026-04-24 sky-debug session:

  #1 — Rain falls only to horizon, not to player (weather/particles)
  #2 — Lightning visual not wired (dat-baked PES triggers; research done)
  #3 — Client clock drifts from retail after ~10 min (periodic TimeSync)
  #4 — Sky horizon-glow disabled (fog-mix skipped on sky meshes)

CLAUDE.md adds an "Issue tracking" section right after roadmap
discipline with the four maintenance rules: (1) scan OPEN at session
start, (2) add/close at session end, (3) reference IDs in commit
messages, (4) promote to a Phase if an issue grows. Calls out the
strategic-vs-tactical split so future sessions know when to reach for
the roadmap vs the issues file.

README.md gets one line pointing at `docs/ISSUES.md` below the existing
roadmap link for first-class discoverability.

No code changes; doc-only.

CLAUDE.md

@@ -229,6 +229,27 @@ acdream's plan lives in two files committed to the repo:
 The roadmap is not sacred — it changes. It IS the source of truth at any
 given moment. When it's wrong, fix it. When it's right, follow it.
 
+## Issue tracking — `docs/ISSUES.md`
+
+Tactical rolling list of known bugs + small deferred features. Scope:
+anything that fits in one-to-two commits; larger work stays as a Phase
+in the roadmap. Maintenance rules:
+
+1. **Start-of-session:** scan OPEN issues in `docs/ISSUES.md` — any of
+   them in the area you're about to touch? Plan accordingly.
+2. **End-of-session:** if this session observed a defect and didn't fix
+   it inline, add an issue. If this session fixed an OPEN issue, move
+   it to **Recently closed** with the commit SHA.
+3. **Commit messages:** reference issue IDs when a commit closes one
+   (`fix #3: periodic TimeSync parsing`). Makes `git log --grep='#3'`
+   return the full fix history.
+4. **Promotion:** if an issue grows into multi-commit work, promote it
+   to a Phase in the roadmap. Close the issue as
+   `DONE (promoted to Phase X)` and reference the roadmap commit.
+
+The roadmap is strategic (month-scale, phase-level). ISSUES is tactical
+(week-scale, bug-level). They reference each other but don't duplicate.
+
 ## Running the client against the live server
 
 The user runs a **local ACE (Asheron's Call Emulator) server on

README.md

@@ -51,6 +51,8 @@ are still stubbed or in-progress — see roadmap.
   vs retail's several kilometres
 
 See `docs/plans/2026-04-11-roadmap.md` for the ordered phase list.
+See `docs/ISSUES.md` for the rolling list of known bugs + small deferred
+features (tactical, bug-level; the roadmap is strategic, phase-level).
 
 ## Building + running
 

docs/ISSUES.md

@@ -0,0 +1,153 @@
+# acdream — known issues + small deferred features
+
+Rolling tactical list. What goes here:
+
+- **Bugs**: user-visible defects we've observed but haven't fixed yet.
+- **Small deferred features**: work that fits in one or two commits.
+  Anything larger should be a named Phase in the [roadmap](plans/2026-04-11-roadmap.md).
+
+What does NOT go here:
+
+- Large multi-commit work → add a Phase to the roadmap instead.
+- Ideas / wishlist → `docs/plans/`.
+- Design questions → open a `docs/research/*.md` note.
+
+## Conventions
+
+- Sequential integer IDs (`#1`, `#2`, …). Commits that close an issue reference the ID in the message (e.g. `fix #3: periodic TimeSync parsing`).
+- `Status` is `OPEN`, `IN-PROGRESS`, or `DONE`. DONE items move to the **Recently closed** section at the bottom with closed-date + commit SHA.
+- Every session: scan OPEN issues at start; promote/close anything we touched during the session before ending.
+- Promoting to a Phase: mark as `DONE (promoted to Phase X)` + commit SHA where the Phase entry landed.
+
+## Template
+
+Copy this block when adding a new issue:
+
+```
+## #NN — Short title
+
+**Status:** OPEN
+**Severity:** HIGH | MEDIUM | LOW
+**Filed:** YYYY-MM-DD
+**Component:** e.g. sky, physics, net, ui
+
+**Description:** One paragraph — what's wrong or what's missing.
+
+**Root cause / status:** What we know so far. Empty if unknown.
+
+**Files:** Path references with approximate line numbers.
+
+**Research:** Links to `docs/research/*.md` if applicable.
+
+**Acceptance:** How we'll know it's fixed.
+```
+
+---
+
+# Active issues
+
+## #1 — Rain falls only to horizon, not to the player's feet
+
+**Status:** OPEN
+**Severity:** MEDIUM
+**Filed:** 2026-04-25
+**Component:** weather / particles
+
+**Description:** During Rainy DayGroups, rain particles are visible in the upper sky band but fade out before reaching the camera / ground level. Retail's rain falls all the way past the camera to the terrain.
+
+**Root cause / status:** Unknown. Likely one of: (a) particle emitter volume too short in Z, (b) particle lifetime shorter than the time it takes to traverse emitter-top → ground, (c) emitter anchored in world-space so particles escape the player's reference frame as they fall, (d) camera-relative spawn origin is offset too high above the player.
+
+**Files:**
+- `src/AcDream.App/Rendering/GameWindow.cs` — `UpdateWeatherParticles` (~line 4591)
+- `src/AcDream.Core/Vfx/ParticleSystem.cs` — emitter spawn config + lifetime integration
+
+**Research:** `docs/research/deepdives/r12-weather-daynight.md` (rain mechanism — but does not pin volume / lifetime values).
+
+**Acceptance:** Standing at 9,115 in Holtburg during a Rainy DayGroup, rain drops visibly fall all the way from the sky band past the camera to the ground level.
+
+---
+
+## #2 — Lightning visual not wired (dat-baked PES triggers)
+
+**Status:** OPEN
+**Severity:** MEDIUM
+**Filed:** 2026-04-25
+**Component:** weather / sky / vfx
+
+**Description:** Retail's Rainy DayGroup in the Dereth Region dat contains 12+ `SkyObject` entries with non-zero `PesObjectId` and narrow visibility windows (5–70 ms at keyframe-boundary moments) that drive PhysicsScript-authored flash + thunder effects. We render the sky meshes but ignore the PES path, so no lightning flashes appear during storms. The fragment-shader flash bump on `uFogParams.z` is already wired in `sky.frag` — only the CPU-side PES→runner wire is missing.
+
+**Root cause / status:** Research complete. Implementation is: in `SkyRenderer.Render`, detect visibility-window entry on any SkyObject with `obj.PesObjectId != 0`, call `PhysicsScriptRunner.Play(pesObjectId, ownerId: sky-owner, anchorPos: camera)`, and route any `SetFlash` / `Sound` hooks from the script into `uFogParams.z` + audio.
+
+**Files:**
+- `src/AcDream.App/Rendering/Sky/SkyRenderer.cs` — add per-SkyObject PES dispatch inside the visibility loop
+- `src/AcDream.Core/Vfx/PhysicsScriptRunner.cs` — already shipped (Phase 6a); exposes `Play(scriptId, entityId, anchorWorldPos)`
+- `src/AcDream.Core/Lighting/SceneLightingUbo.cs` — `FogParams.Z` is the flash slot; needs a sink that bumps it and decays
+- `src/AcDream.App/Rendering/Shaders/sky.frag` — flash bump already wired (`rgb += flash * vec3(1.5, 1.5, 1.8)`)
+
+**Research:**
+- `docs/research/2026-04-23-lightning-real.md` (decompile trace + dat discovery)
+- `docs/research/2026-04-23-physicsscript.md` (runtime semantics)
+- `docs/research/2026-04-23-lightning-crossfade.md` (crossfade mechanism)
+
+**Acceptance:** During a Rainy DayGroup's storm window, visible flashes appear in the sky at the dat-scripted moments, the fragment-shader flash bump briefly brightens the scene, and (later, once thunder audio is wired) a thunder clap plays with a short propagation delay.
+
+---
+
+## #3 — Client clock drifts from retail after ~10 minutes (periodic TimeSync missing)
+
+**Status:** OPEN
+**Severity:** MEDIUM
+**Filed:** 2026-04-25
+**Component:** net / sky
+
+**Description:** Our `WorldTimeService.DayFraction` syncs with the server once at login via `ConnectRequest + TimeSync`, then advances from the local wall-clock. Retail receives periodic `TimeSync` refreshes (header flag `0x1000000`) carrying a fresh `PortalYearTicks double` and re-anchors its clock. Without those, acdream's keyframe state drifts from retail's over 10+ minutes — observed during the 2026-04-24 sky-color debug sessions where retail was at DayFraction 0.976 while acdream was at 0.634.
+
+**Root cause / status:** Mechanism is well-understood (see research). `WorldTimeService.SyncFromServer(double)` already exists — we just need to detect the periodic flag in the packet header and call it whenever a fresh tick arrives.
+
+**Files:**
+- `src/AcDream.Core.Net/WorldSession.cs` — header-flag parsing; currently only the initial sync is consumed
+- `src/AcDream.Core/World/WorldTimeService.cs` — `SyncFromServer(double ticks)` ready; needs caller wiring
+
+**Research:** `docs/research/deepdives/r12-weather-daynight.md` §TimeSync (line ~563). References retail packet-header flag `0x1000000` carrying `PortalYearTicks double`.
+
+**Acceptance:** Probe retail via `tools/RetailTimeProbe` and acdream's ACDREAM_DUMP_SKY log at the same wall-clock moment after a 20-minute session without re-login; `abs(acdream.DayFraction - retail.DayFraction) < 0.01`.
+
+---
+
+## #4 — Sky horizon-glow disabled (fog-mix skipped on sky meshes)
+
+**Status:** OPEN
+**Severity:** LOW (aesthetic feature-parity, not regression from pre-session state)
+**Filed:** 2026-04-25
+**Component:** sky
+
+**Description:** Phase 8.1 (commit `593b76f`) disabled the fog-mix on sky meshes to fix the "entire dome swallowed by fog color" regression. Dereth's keyframe `FogEnd` values (0–2400 m) are calibrated for terrain; sky meshes are authored at radii 1050–14271 m so every sky pixel was past `FogEnd`, saturated to `uFogColor`, destroying stars / moon / dome texture. Disabling the mix restored visibility but we lost retail's horizon-glow effect (gradient from clear zenith to fog-tinted horizon band at dusk/dawn).
+
+**Root cause / status:** Three competing hypotheses, none pinned down: (a) retail uses a **different** fog range for sky than terrain; (b) retail applies fog with an **elevation-angle** weighting rather than linear distance; (c) retail's sky meshes **don't participate** in the global fog and the "horizon glow" comes from a different atmospheric-scatter path. Need to identify retail's actual sky-fog behaviour before re-enabling with correct parameters.
+
+**Files:**
+- `src/AcDream.App/Rendering/Shaders/sky.frag` — line ~55, `rgb = mix(uFogColor.rgb, rgb, vFogFactor)` currently commented out
+- `src/AcDream.App/Rendering/Shaders/sky.vert` — lines 109-114, `vFogFactor` computation
+
+**Research:** `docs/research/2026-04-23-sky-fog.md`. Partial; doesn't pin the sky-specific fog path.
+
+**Acceptance:** At dusk in Holtburg, the sky dome shows a clear zenith and a warm fog-tinted horizon band that matches retail's appearance, with stars / moon / sun / clouds all still visible at their correct brightnesses elsewhere in the frame.
+
+---
+
+# Recently closed
+
+*(none yet — move DONE items here with closed-date + commit SHA)*
+
+<!--
+Example:
+
+## #0 — [DONE 2026-04-24 · 593b76f] Sky cube edges visible as cross in daytime sky
+
+**Closed:** 2026-04-24
+**Commit:** `593b76f sky(phase-8.1): CLAUDE_TO_EDGE on static sky meshes`
+**Resolution:** Switched to `GL_CLAMP_TO_EDGE` wrap mode for static sky
+meshes; scrolling cloud layers kept `GL_REPEAT`. The 5 dome walls were
+sampling opposite-edge pixels via UV wrap + LINEAR filtering, producing
+visible seam lines that formed a cube outline across the view.
+-->