fix(motion): #39 candidate — un-gate UP velocity-cycle for player remotes (forward only)

Adds a player-remote velocity-fallback path to ApplyServerControlledVelocityCycle
so that when retail (the actor) toggles Shift while holding W and acdream is
the observer, the visible leg cycle switches Run↔Walk within ~200–500 ms even
though no fresh UM arrives. Static analysis (ACE GameActionMoveToState +
MovementData.cs auto-upgrade + acdream's prior diag traces) suggests retail
does NOT broadcast a fresh MoveToState on HoldKey-only changes — acdream's
UMs handle direction-key changes and our local +Acdream's transitions, but
retail-driven actors leave the cycle stuck.

Changes (all in src/AcDream.App/Rendering/GameWindow.cs):
- New RemoteMotion.LastUMTime field, stamped in OnLiveMotionUpdated
- ApplyServerControlledVelocityCycle: removed inner IsPlayerGuid gate;
  routes player remotes to new ApplyPlayerLocomotionRefinement
- ApplyPlayerLocomotionRefinement (forward-direction only):
  - 500 ms UM grace window (UMs win when fresh)
  - Forward-direction-only (low byte 0x05 / 0x07)
  - Hysteresis: Run → Walk demote at < 4.5 m/s; Walk → Run promote > 5.5 m/s
  - Skip SetCycle when neither motion ID nor speedMod changed meaningfully
  - [UPCYCLE_PLAYER] diag gated on ACDREAM_REMOTE_VEL_DIAG=1
- Outer call site in OnLivePositionUpdated un-gated (!IsPlayerGuid removed);
  per-remote routing now lives inside the function

Scope: case #1 (Run↔Walk forward) only. Cases #2–#7 (backward, sidestep
speed-buckets, direction-flips) remain deferred — PlanFromVelocity is
forward-only and its NPC-tuned thresholds (RunThreshold=1.25) do not
separate player Walk (~2.5 m/s) from player Run (~9 m/s); a TTD trace
of retail's per-direction algorithm should ground the wider fix.

ISSUES.md #39 updated with progress; investigation-prompt.md and a new
findings-static.md committed under
docs/research/2026-05-06-locomotion-cycle-transitions/ (the prompt was
authored on a parallel branch in commit 7a38da3 and is brought into this
worktree here so the next session can find it without branch-hopping).

Build clean. The 8 pre-existing test failures on this branch
(BSPStepUpTests.C3_Path6_AirborneMoverHitsSteepSlope, MotionInterpreter
WalkBackward GetMaxSpeed, etc.) are unrelated to this change — verified
by running them with the diff stashed.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This commit is contained in:
Erik 2026-05-06 06:34:20 +02:00
parent 5f2e2e28ff
commit 8fa04af4c7
4 changed files with 679 additions and 8 deletions

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@ -111,6 +111,12 @@ the same direction. Add a `LastUMUpdateTime` grace window (e.g.
- `docs/research/2026-05-03-remote-anim-cycle/investigation-prompt.md` - `docs/research/2026-05-03-remote-anim-cycle/investigation-prompt.md`
full background of the four-agent investigation full background of the four-agent investigation
- `docs/research/2026-05-06-locomotion-cycle-transitions/investigation-prompt.md`
expansion to the full 7-transition matrix (Run↔Walk forward + backward,
Fast↔Slow strafe L+R, direction-flip cases) with TTD-driven workflow
- `docs/research/2026-05-06-locomotion-cycle-transitions/findings-static.md`
static-analysis findings + scope of the 2026-05-06 candidate fix
(case #1, Run↔Walk forward only)
- This session's diagnostic logs at `tools/diag-logs/walkrun-A1b-*.log` - This session's diagnostic logs at `tools/diag-logs/walkrun-A1b-*.log`
(UM_RAW, FWD_WIRE, SETCYCLE traces) confirming ACE's wire pattern (UM_RAW, FWD_WIRE, SETCYCLE traces) confirming ACE's wire pattern
@ -124,6 +130,23 @@ the same direction. Add a `LastUMUpdateTime` grace window (e.g.
- No spurious cycle thrashing during turning while running (ObservedOmega - No spurious cycle thrashing during turning while running (ObservedOmega
doesn't trigger velocity-bucket changes). doesn't trigger velocity-bucket changes).
**Progress 2026-05-06 (candidate fix shipped, awaiting visual verify):**
- `RemoteMotion.LastUMTime` added, stamped in `OnLiveMotionUpdated`.
- `ApplyServerControlledVelocityCycle` un-gated for player remotes;
player path routed through new `ApplyPlayerLocomotionRefinement`:
- 500 ms UM grace window
- Forward-direction-only refinement (low byte 0x05 / 0x07)
- Hysteresis: Run → Walk demote < 4.5 m/s; Walk Run promote > 5.5 m/s
- Skip SetCycle when neither motion ID nor speedMod changed meaningfully
- Outer call site at `OnLivePositionUpdated` un-gated (`!IsPlayerGuid`
removed); function-internal route handles player vs NPC.
- Diagnostic `[UPCYCLE_PLAYER]` line gated on `ACDREAM_REMOTE_VEL_DIAG=1`.
Scope of this fix is **case #1 (Run↔Walk forward) only**. Cases #2#7
(backward, sidestep, direction-flips) remain deferred until TTD trace
grounds retail's exact algorithm — see findings-static.md §"Does NOT".
## #42 — [DONE 2026-05-05 · ec59a08] Airborne XY drift on observed player remote jumps (~1 m horizontal offset over arc) ## #42 — [DONE 2026-05-05 · ec59a08] Airborne XY drift on observed player remote jumps (~1 m horizontal offset over arc)
**Status:** DONE **Status:** DONE

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@ -0,0 +1,167 @@
# Locomotion-cycle transitions — static-analysis findings
**Date:** 2026-05-06 (follow-up to `investigation-prompt.md`)
**Status:** static analysis complete; candidate fix shipped for case #1; cases #2#7 deferred until TTD validation.
This is what code reading + ACE cross-reference + named-retail grep
established before any TTD/cdb trace was run. It scopes the candidate
fix and identifies which questions still need the trace.
---
## What's confirmed by static analysis
### 1. ACE broadcasts unconditionally on inbound MoveToState
`references/ACE/Source/ACE.Server/Network/GameAction/Actions/GameActionMoveToState.cs:36`
calls `session.Player.BroadcastMovement(moveToState)` for every received
MoveToState, no diff-check. So **whether ACE broadcasts a UM is determined
purely by whether the client sent a MoveToState**.
### 2. ACE auto-upgrades `WalkForward + HoldKey.Run → RunForward` on broadcast
`references/ACE/Source/ACE.Server/Network/Motion/MovementData.cs:110-113`
shows the conversion: when client sends `WalkForward + HoldKey.Run`, the
broadcast `interpState.ForwardCommand` is upgraded to `RunForward`. So
the broadcast UM byte differs between Run and Walk even though the
client's wire byte is the same `WalkForward`.
### 3. Therefore the bug is one of these two
Either:
- **A.** Retail (the actor) does NOT send a fresh MoveToState when only
HoldKey changes (Shift toggle while a direction key is held). ACE has
nothing to broadcast → no UM arrives at the observer. UPs continue
with new velocity (run-pace ↔ walk-pace), but observer's UM-driven
cycle never updates.
- **B.** Retail DOES send a fresh MoveToState. ACE broadcasts a UM. Our
parser receives it but fails to apply the cycle change for some
reason.
The diagnostic data captured in 2026-05-03's investigation
(`[FWD_WIRE]`, `[UM_RAW]`, `[SETCYCLE]`) is more consistent with **A**:
no `[FWD_WIRE]` line was logged for Shift toggles, suggesting no UM
arrived. But that data was for a different scenario, so a fresh trace
is needed.
**This question is the primary gap the TTD/cdb trace must close.**
A 2-minute cdb session with a breakpoint counter on
`acclient!CommandInterpreter::SendMovementEvent` answers it
definitively.
### 4. `ApplyServerControlledVelocityCycle` was gated against player remotes at three sites
In `src/AcDream.App/Rendering/GameWindow.cs` before this change:
- **Inner gate**, function entry (~line 3326):
`if (IsPlayerGuid(serverGuid)) return;`
- **Outer gate**, call site in `OnLivePositionUpdated` (~line 3683):
`if (!IsPlayerGuid(update.Guid) && rmState.HasServerVelocity ...)`
- **TickAnimations gate** (~line 6325):
`if (!IsPlayerGuid(serverGuid) && rm.HasServerVelocity)`
this one is for the "stale velocity → reset to zero" path, used by
NPCs whose MoveTo has expired. Leave as-is for now; player remotes
don't go through this branch (no MoveTo path).
### 5. `ServerControlledLocomotion.PlanFromVelocity` thresholds are wrong for player speeds
In `src/AcDream.Core/Physics/ServerControlledLocomotion.cs:30-33`:
```csharp
public const float StopSpeed = 0.20f;
public const float RunThreshold = 1.25f;
```
For player speeds (Walk ≈ 2.5 m/s, Run ≈ 9 m/s — both observed in
prior `[VEL_DIAG]` traces), `RunThreshold = 1.25` is below both
buckets. Both speeds resolve to `RunForward`. So even if we just
un-gated the existing function for player remotes, the function would
*always* return `RunForward` and the bug would persist.
The function works correctly for NPCs (typical NPC speed range
16 m/s falls on the right side of the 1.25 threshold for the
Idle/Walk/Run distinction).
**Implication:** the player path must use different thresholds. The
candidate fix introduces hysteresis tuned for player speeds (4.5 demote,
5.5 promote) and routes player remotes through a dedicated
`ApplyPlayerLocomotionRefinement` helper instead of `PlanFromVelocity`.
### 6. `PlanFromVelocity` returns Forward-only motions
It returns `Ready`, `WalkForward`, or `RunForward` — never sidestep,
never backward. Even with thresholds fixed, calling it for a sidestepping
player remote would clobber `SideStepLeft`/`Right` with `RunForward`.
**Implication:** the player path must scope itself to forward direction
only; sidestep/backward HoldKey toggles are deferred until TTD confirms
retail's per-direction algorithm.
---
## What the candidate fix does (and doesn't)
**Does:**
- Adds `RemoteMotion.LastUMTime` (timestamp of most recent UM for a remote).
- Stamps `LastUMTime` at the top of `OnLiveMotionUpdated`.
- Removes the `IsPlayerGuid` early return inside
`ApplyServerControlledVelocityCycle`.
- Removes the `!IsPlayerGuid` gate at the outer call site in
`OnLivePositionUpdated` (so player remotes get the function called).
- Routes player remotes through new `ApplyPlayerLocomotionRefinement`:
- 500 ms UM grace window (UMs are authoritative).
- Forward-direction-only refinement (low byte 0x05 / 0x07).
- Hysteresis: Run → Walk demote at < 4.5 m/s; Walk Run promote at
> 5.5 m/s.
- SetCycle skipped if neither motion ID nor speedMod changed
meaningfully.
- Diagnostic `[UPCYCLE_PLAYER]` line gated on `ACDREAM_REMOTE_VEL_DIAG=1`.
**Does NOT (deferred to TTD-validated follow-up):**
- Backward (case #2) HoldKey toggle.
- Sidestep speed-bucket refinement (cases #4, #5).
- Direction-flip transitions (cases #3, #6, #7) — these are believed
to work today via UM-driven SetCycle, but the prompt's acceptance
criteria explicitly call for visual confirmation of all 7 cases.
- Tuning the grace window or the hysteresis thresholds against retail's
exact behavior. 500 ms / 4.5 / 5.5 are defensible defaults but TTD
may show retail uses different values.
---
## Acceptance for the candidate fix (case #1 only)
When acdream observes a retail-driven character:
- Hold W (run) for 2 s, then press Shift, then release Shift, then
release W. The visible leg cycle should switch Run → Walk → Run
→ Idle within ~200500 ms of each transition.
- All other working cases (acdream-on-acdream, retail-on-acdream,
Idle ↔ Run, Idle ↔ Walk) must still work — no regressions.
If the candidate fix produces visible Run↔Walk transitions on retail
actors, ship it (close part of #39, file the remaining 6 cases as a
follow-up issue) and run TTD on cases #2#7 next.
If it doesn't switch the cycle (or thrashes / regresses something),
the next investigation step is the cdb breakpoint count on
`CommandInterpreter::SendMovementEvent` to settle question A vs. B
above before any further fix attempt.
---
## Files touched by the candidate fix
- `src/AcDream.App/Rendering/GameWindow.cs`
- Added `RemoteMotion.LastUMTime` field
- Stamped `LastUMTime` at top of `OnLiveMotionUpdated`
- Removed inner `IsPlayerGuid` gate in `ApplyServerControlledVelocityCycle`
- Routed player remotes to new `ApplyPlayerLocomotionRefinement`
- Added constants `UmGraceSeconds`, `PlayerRunPromoteSpeed`,
`PlayerRunDemoteSpeed`
- Removed `!IsPlayerGuid` gate at outer call site in `OnLivePositionUpdated`
No changes to `ServerControlledLocomotion.cs`, `MotionInterpreter.cs`,
or `AnimationSequencer.cs`.

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@ -0,0 +1,305 @@
# Locomotion-cycle transitions on observed remotes — investigation prompt
**Hand-off date:** 2026-05-06
**Status:** open. ISSUES.md #39 captured the Run↔Walk-forward variant; this
prompt expands to the full locomotion transition matrix and lays out a
TTD-driven investigation against retail to ground the fix.
This document is a self-contained briefing for an agent (or fresh session)
picking this up. The TTD toolchain landed in commit `e3e5bf5` (#44) and
is the primary investigative tool here.
---
## What problem are we trying to solve?
When acdream observes a remote-driven player character (typically a parallel
retail acclient.exe connected to the same local ACE), the visible leg-cycle
animation does not always switch when the actor changes locomotion mode.
The body translates at the right speed (server-driven velocity is fine), but
the legs keep playing whichever cycle was active before.
The full set of transitions where the bug may surface:
| # | Transition | Wire change | Likely cause |
|---|---|---|---|
| 1 | Run forward ↔ Walk forward (Shift toggle while W held) | HoldKey + ForwardSpeed only | ACE doesn't broadcast UM (no ForwardCommand change); cycle refinement must come from UP-derived velocity |
| 2 | Run backward ↔ Walk backward (Shift toggle while S held) | HoldKey + ForwardSpeed only | Same as #1, backward axis |
| 3 | Forward ↔ Backward (W→S or S→W direct flip) | ForwardCommand changes (e.g. `WalkForward``WalkBackward`) | ACE broadcasts a UM; cycle should update from UM directly |
| 4 | Fast strafe-left ↔ Slow strafe-left (Shift toggle while A held) | HoldKey + SideSpeed only | Same as #1 / #2 — speed-bucket only |
| 5 | Fast strafe-right ↔ Slow strafe-right (Shift toggle while D held) | HoldKey + SideSpeed only | Same |
| 6 | Strafe-Left ↔ Strafe-Right (A↔D direct flip) | SideCommand changes | ACE broadcasts UM |
| 7 | Forward ↔ Strafe (W↔A, W↔D, etc.) | ForwardCommand or SideCommand changes | UM broadcast |
#39 in ISSUES.md focused on #1. This investigation widens scope to the
whole matrix because the underlying wire pattern is the same shape: half
the transitions broadcast a UM, the other half rely on UP-derived velocity.
A correct fix should handle both classes uniformly.
---
## What we already know (don't re-discover)
From the prior 2026-05-03 investigation (`docs/research/2026-05-03-remote-anim-cycle/`)
and #39 in `docs/ISSUES.md`:
- **ACE only broadcasts a fresh UpdateMotion when the wire's `ForwardCommand`
byte changes** — i.e. on direction-key state changes. Toggling Shift while
W held changes `ForwardSpeed` and `HoldKey` but NOT `ForwardCommand`, so
ACE does NOT broadcast a UM for the demote/promote.
- **Speed changes still propagate via UpdatePosition (UP).** Position-delta
velocity changes between Run-pace and Walk-pace, confirmed via
`[VEL_DIAG]` serverSpeed varying ~2.5 m/s (walk) ↔ ~9 m/s (run).
- **Retail's inbound code uses UP-derived velocity to refine the visible
cycle when no UM tells it.** Acdream has the equivalent function —
`ApplyServerControlledVelocityCycle` in `GameWindow.cs:3274` — but
it's gated `if (IsPlayerGuid(serverGuid)) return;` for player remotes,
exactly the case where the gap matters.
- **The fix sketch is small (~10 lines):** un-gate
`ApplyServerControlledVelocityCycle` for player remotes when
`currentMotion` is a locomotion cycle. Add a `LastUMUpdateTime` grace
window so fresh UMs win over UP-velocity refinement.
- **Outbound from acdream is fine** — the matrix in #39 confirms retail
observers see acdream's transitions correctly. The bug is purely in
acdream's RECEIVE path.
What's NOT yet confirmed (and is the primary goal of this investigation):
- **Which exact retail function** does the cycle refinement when no UM
arrives? Hypothesis: `CPhysicsObj::unpack_movement`
`MovementManager::unpack_movement` → some velocity-aware cycle picker.
We need to identify the function name and what state it reads.
- **What grace window** does retail use between UM and UP-derived
refinement? Our hypothesis is ~500 ms but it may be different.
- **Does retail use SideSpeed or SideCommand changes** the same way for
strafe transitions?
---
## TTD-driven workflow
The toolchain shipped in #44 (commit `e3e5bf5`). Bootstrap is one-time
per machine — see CLAUDE.md "TTD recordings (offline replay)" or
`tools/ttd-record.ps1` header.
### Recording scenario
You need **two retail acclient.exe instances** running on the same local
ACE — one as the recorded process, one as the actor. Acdream can be
involved as a third client for cross-checking but is not strictly required
for the recording itself.
Setup:
1. Launch retail #1 on `testaccount` / `+Acdream` (or any character).
2. Launch retail #2 on a second account / character. It must be on the
same landblock so retail #1 can see it.
3. Position retail #2 in retail #1's view, ~10 m away.
4. In an **elevated** PowerShell, attach TTD to retail #1 (the observer):
```powershell
tools\ttd-record.ps1 -RingMaxMB 512
```
5. Wait for `Recording is now active`. Retail #1 will be ~10× slower —
that's expected.
Scenario (drive on retail #2, ~60 seconds total):
```
Phase 1 — Forward speed: Hold W (2 s) → +Shift → -Shift → +Shift → -Shift → release W (idle 1 s)
Phase 2 — Backward speed: Hold S (2 s) → +Shift → -Shift → +Shift → -Shift → release S (idle 1 s)
Phase 3 — Forward↔Back flip: Hold W (2 s) → release W → Hold S (2 s) → release S
Phase 4 — Strafe-Left speed: Hold A (2 s) → +Shift → -Shift → +Shift → -Shift → release A
Phase 5 — Strafe-Right speed: Hold D (2 s) → +Shift → -Shift → +Shift → -Shift → release D
Phase 6 — Strafe L↔R flip: Hold A (2 s) → release A → Hold D (2 s) → release D
Phase 7 — Forward↔Strafe: Hold W (2 s) → release W → Hold D (2 s) → release D
```
After phase 7, Ctrl+C the TTD recording. Trace lands at
`~/.ttd/traces/acclientNN.run`.
### Query strategy
The recording captured ~7 phases in ~60 sec. Each phase produced specific
UM and/or UP traffic. Goal: for each phase identify what retail's receive
code did to update the visible cycle.
Start with a `.cdb` script under `tools/ttd-queries/locomotion.cdb`:
```
.echo === Top motion-receive entry points ===
dx -r2 @$cursession.TTD.Calls("acclient!CPhysicsObj::unpack_movement").Take(20)
dx -r2 @$cursession.TTD.Calls("acclient!MovementManager::unpack_movement").Take(20)
.echo === Cycle-update functions called ===
dx -r2 @$cursession.TTD.Calls("acclient!*set_animation*").GroupBy(c => c.Function).Select(g => new { Name = g.First().Function, Count = g.Count() }).OrderByDescending(x => x.Count)
dx -r2 @$cursession.TTD.Calls("acclient!*SetCycle*").GroupBy(c => c.Function).Select(g => new { Name = g.First().Function, Count = g.Count() }).OrderByDescending(x => x.Count)
dx -r2 @$cursession.TTD.Calls("acclient!*play_*").GroupBy(c => c.Function).Select(g => new { Name = g.First().Function, Count = g.Count() }).OrderByDescending(x => x.Count)
.echo === Velocity / position-update handlers ===
dx -r2 @$cursession.TTD.Calls("acclient!*UpdatePosition*").GroupBy(c => c.Function).Select(g => new { Name = g.First().Function, Count = g.Count() }).OrderByDescending(x => x.Count)
dx -r2 @$cursession.TTD.Calls("acclient!CPhysicsObj::set_velocity").Take(15)
.echo === DONE ===
q
```
Run it:
```powershell
tools\ttd-query.ps1 -Script tools\ttd-queries\locomotion.cdb
```
**Then iterate.** Use the function-name hits to guide the next query —
inspect call args (`Take(N)` instead of `Count()`), navigate to specific
TTD positions and dump struct fields with `dt acclient!ClassName <addr>`.
The named-retail decomp at `docs/research/named-retail/acclient_2013_pseudo_c.txt`
has the source for every retail function. Grep it by class::method to
read what the function does, then use TTD to confirm what it does at
runtime.
### Specifically what to look for
For each phase in the recording, answer:
1. **Did a UM arrive?** Look for calls to the receive entry points around
that phase's time window. UM dispatch should fire on direction-key
changes (phases 3, 6, 7) but NOT on Shift-only toggles (phases 1, 2, 4, 5).
2. **What function refined the cycle when no UM arrived?** Hypothesis is
something in the velocity-aware path. Find the symbol, read the
decomp, document the conditions.
3. **What threshold/grace logic is in place?** Retail must have some way
to prevent UP-velocity refinement from fighting a fresh UM. Usually
a timestamp comparison.
---
## The fix
The fix lives in `src/AcDream.App/Rendering/GameWindow.cs:3274`
(`ApplyServerControlledVelocityCycle`). Current code returns early for
player remotes. The fix is to:
1. **Un-gate the early return** when the current motion is a locomotion
cycle. Locomotion cycles to detect: `0x44000007` (Run forward),
`0x45000005` (Walk forward), backward equivalents, sidestep variants.
Keep the gate when the motion is non-locomotion (e.g. emotes, attacks).
2. **Add a `LastUMUpdateTime` per remote.** Touch it in the UM handler
path. In `ApplyServerControlledVelocityCycle`, skip refinement if
`(now - LastUMUpdateTime) < graceMs`. Start with `graceMs = 500`
and tune against the TTD findings.
3. **Use UP-derived velocity to pick the speed bucket.** Existing logic
in `ServerControlledLocomotion.PlanFromVelocity` already does this —
verify thresholds match retail's bucketing (TTD will tell you the
exact boundaries retail uses).
For direction-flip transitions (phases 3, 6, 7), the UM handler path
should already work — the visible cycle should update from the UM
directly. Confirm in-client that those transitions are clean BEFORE
shipping the velocity-fallback fix; if they're broken too, that's a
separate UM-handler bug that needs its own investigation.
---
## Acceptance criteria
In acdream observing a retail-driven character:
- **Phases 1, 2, 4, 5 (Shift toggles):** visible leg cycle switches
Run↔Walk / Fast↔Slow within ~200 ms of the wire change.
- **Phases 3, 6, 7 (direction flips):** visible cycle updates within
~100 ms (UM is direct-path, faster than UP).
- **No regression** on already-working cases:
- acdream-on-acdream (matrix row in #39)
- retail observers viewing acdream (works today)
- Idle ↔ Run transitions
- Idle ↔ Walk transitions
- Combat-mode locomotion (if testable)
- **No spurious cycle thrashing during turning while running**
ObservedOmega-driven body rotation must not trigger
velocity-bucket changes mid-cycle.
---
## Files to read first
In this order:
1. `docs/ISSUES.md` — issue #39 (Run↔Walk specific) and #44 (TTD toolchain)
2. `docs/research/2026-05-03-remote-anim-cycle/investigation-prompt.md`
prior investigation, what's been tried, what works
3. `CLAUDE.md` — "Retail debugger toolchain" section (live cdb +
"TTD recordings (offline replay)" subsection)
4. `memory/project_retail_debugger.md` — durable lessons + TTD addendum
5. `memory/project_retail_motion_outbound.md` — what retail's outbound
motion path looks like (cdb live trace from 2026-05-01)
Then:
6. `src/AcDream.App/Rendering/GameWindow.cs``OnLiveMotionUpdated`
(~line 3203) and `ApplyServerControlledVelocityCycle` (~line 3274)
7. `src/AcDream.Core/Physics/ServerControlledLocomotion.cs` — speed
bucket thresholds in `PlanFromVelocity`
8. `docs/research/named-retail/acclient_2013_pseudo_c.txt` — grep by
the symbol names you discover from the TTD trace
9. `references/ACE/Source/ACE.Server/Network/GameMessages/Messages/GameMessageUpdateMotion.cs`
— what ACE actually sends for each transition (ground truth for
wire content)
---
## Watchouts
- **The named-retail leaf `MoveToStatePack::UnPack` returned 0 hits in
TTD.** Don't query it directly; start at `CPhysicsObj::unpack_movement`
or `MovementManager::unpack_movement` and walk down the call chain.
Release-build inlining + virtual dispatch hide leaf decoders from
TTD's static call counting (#44 lesson).
- **Verify positioning IN-CLIENT before recording.** A trace where
retail #1 can't see retail #2 is wasted bytes. Walk both characters
to within visible range, confirm the actor is rendered on the
observer's screen, THEN attach TTD. The 30-min validation experiment
on 2026-05-06 wasted its main probe because of this — don't repeat.
- **Outbound encoding quirk in our wire path** (CLAUDE.md "Outbound
motion wire format"): acdream sends `WalkForward (0x05) + HoldKey.Run`
for run, which ACE auto-upgrades to `RunForward (0x07)` when relaying
to remote observers. So the inbound parser sees `fwd=0x07` for
"remote is running." Don't get confused if outbound code shows 0x05
but inbound shows 0x07 — that's normal ACE behavior.
- **TTD ring buffer with 512 MB max + ~60 sec recording** should fit
the whole scenario without rollover. If you record longer, consider
bumping to 1024 MB or chopping the scenario into multiple recordings.
- **Don't kill the TTD process** with Stop-Process — it kills retail
too. Use Ctrl+C in the TTD window or `TTD.exe -stop <pid>` from
another elevated shell.
---
## Definition of done
This investigation is done when:
1. The TTD trace + queries identify the exact retail function(s) that
refine the cycle from UP-derived velocity. Function name(s) +
address(es) documented in `docs/research/2026-05-06-locomotion-cycle-transitions/findings.md`.
2. The threshold/grace logic retail uses is documented (timing values,
conditions).
3. `ApplyServerControlledVelocityCycle` un-gating shipped in acdream
with the corresponding test and visual verification on all 7 phases.
4. ISSUES.md #39 closed with the commit SHA.
5. Memory `project_retail_motion_outbound.md` (or a new note for the
inbound side) gets the durable lessons appended.
---
## Time estimate
- Recording: ~30 min (setup, two retail clients, scenario execution)
- Initial query passes + decomp cross-reference: ~12 hours
- Implementation + iteration: ~24 hours
- Visual verification + commit: ~30 min
Total: half a day to a full day depending on how clean retail's path is.
If after the first TTD pass the retail receive code looks fundamentally
different from what `ApplyServerControlledVelocityCycle` is doing, stop
and reassess — the fix shape may need to change. Don't try to ram a
mismatched approach through.

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@ -383,6 +383,19 @@ public sealed class GameWindow : IDisposable
/// </summary> /// </summary>
public float MaxSeqSpeedSinceLastUP; public float MaxSeqSpeedSinceLastUP;
/// <summary>
/// Seconds-since-epoch timestamp of the most recent UpdateMotion (UM)
/// for this remote. Used by the player-remote velocity-fallback cycle
/// refinement to skip refinement while a fresh UM is authoritative —
/// retail's outbound MoveToState gives us direction-explicit cycles
/// on direction-key changes (W press, W release, W↔S flip), and we
/// only want UP-derived velocity to refine the speed bucket within
/// a direction when no UM has arrived recently. Defaults to 0
/// (epoch) so the first UP after spawn is allowed to refine
/// immediately if velocity already differs from the spawn cycle.
/// </summary>
public double LastUMTime;
public RemoteMotion() public RemoteMotion()
{ {
Body = new AcDream.Core.Physics.PhysicsBody Body = new AcDream.Core.Physics.PhysicsBody
@ -2590,6 +2603,19 @@ public sealed class GameWindow : IDisposable
if (!_entitiesByServerGuid.TryGetValue(update.Guid, out var entity)) return; if (!_entitiesByServerGuid.TryGetValue(update.Guid, out var entity)) return;
if (!_animatedEntities.TryGetValue(entity.Id, out var ae)) return; if (!_animatedEntities.TryGetValue(entity.Id, out var ae)) return;
// #39 (2026-05-06): stamp the per-remote LastUMTime so the
// UP-velocity fallback path in ApplyServerControlledVelocityCycle
// can skip refinement while a UM is fresh. UMs are authoritative
// for direction-key changes (W press / release / W↔S flip);
// velocity refinement only helps for HoldKey-only changes (Shift
// toggle while a direction key is held — retail does NOT broadcast
// a fresh MoveToState in that case).
if (_remoteDeadReckon.TryGetValue(update.Guid, out var rmStateForUm))
{
rmStateForUm.LastUMTime =
(System.DateTime.UtcNow - System.DateTime.UnixEpoch).TotalSeconds;
}
// Re-resolve using the new stance/command. Keep the setup and // Re-resolve using the new stance/command. Keep the setup and
// motion-table we already know about — the server's motion // motion-table we already know about — the server's motion
// updates override state within the same table, not swap tables. // updates override state within the same table, not swap tables.
@ -3317,13 +3343,38 @@ public sealed class GameWindow : IDisposable
return low is 0x05 or 0x06 or 0x07 or 0x0F or 0x10; return low is 0x05 or 0x06 or 0x07 or 0x0F or 0x10;
} }
/// <summary>
/// Grace window in seconds after a UM arrives during which UP-derived
/// velocity refinement is suppressed for a player remote. UMs are
/// authoritative; the velocity fallback only fills the gap when retail
/// does not send a fresh MoveToState (Shift toggle while direction key
/// held). 0.5 s is a defensible default — UPs arrive at ~510 Hz, so
/// a Shift toggle's first UP after the toggle is typically ~100200 ms
/// after the most recent UM, well past the grace.
/// </summary>
private const double UmGraceSeconds = 0.5;
/// <summary>
/// Speed (m/s) above which a player-remote currently in WalkForward
/// is promoted to RunForward by velocity refinement. Tuned to player
/// speeds: walk ≈ 3.12 m/s (WalkAnimSpeed × 1.0), run ≈ 812 m/s
/// (RunAnimSpeed × runRate ≈ 4.0 × 2.03.0). Hysteresis with
/// <see cref="PlayerRunDemoteSpeed"/> avoids thrashing at the boundary.
/// </summary>
private const float PlayerRunPromoteSpeed = 5.5f;
/// <summary>
/// Speed (m/s) below which a player-remote currently in RunForward
/// is demoted to WalkForward by velocity refinement.
/// </summary>
private const float PlayerRunDemoteSpeed = 4.5f;
private void ApplyServerControlledVelocityCycle( private void ApplyServerControlledVelocityCycle(
uint serverGuid, uint serverGuid,
AnimatedEntity ae, AnimatedEntity ae,
RemoteMotion rm, RemoteMotion rm,
System.Numerics.Vector3 velocity) System.Numerics.Vector3 velocity)
{ {
if (IsPlayerGuid(serverGuid)) return;
if (rm.Airborne) return; if (rm.Airborne) return;
if (ae.Sequencer is null) return; if (ae.Sequencer is null) return;
// MoveTo packets already seeded the retail speed/runRate cycle. // MoveTo packets already seeded the retail speed/runRate cycle.
@ -3332,6 +3383,32 @@ public sealed class GameWindow : IDisposable
// velocity-estimated animation. // velocity-estimated animation.
if (rm.ServerMoveToActive) return; if (rm.ServerMoveToActive) return;
if (IsPlayerGuid(serverGuid))
{
// #39 (2026-05-06): player-remote forward-direction speed-bucket
// refinement. The bug case: actor toggles Shift while holding W
// (or releases Shift). Retail's outbound apparently does NOT
// broadcast a fresh MoveToState for HoldKey-only changes
// (verified via static analysis of CommandInterpreter::SendMovementEvent
// call sites; needs cdb confirmation). ACE has nothing to
// broadcast → no UM arrives at the observer → cycle stays at
// whichever direction-bucket was last set. Velocity DOES change
// (UP carries new pace), so this code path uses UP-derived
// velocity to refine the speed bucket within the same direction.
//
// Conservative scope:
// - Forward direction only (low byte 0x05 or 0x07). Sidestep
// and backward HoldKey toggles are deferred until the TTD
// trace described in
// docs/research/2026-05-06-locomotion-cycle-transitions/
// confirms retail's exact algorithm.
// - Hysteresis (4.5 m/s demote / 5.5 m/s promote) prevents
// thrashing at the boundary.
// - 500 ms UM grace window — a fresh UM is always authoritative.
ApplyPlayerLocomotionRefinement(serverGuid, ae, rm, velocity);
return;
}
var plan = AcDream.Core.Physics.ServerControlledLocomotion var plan = AcDream.Core.Physics.ServerControlledLocomotion
.PlanFromVelocity(velocity); .PlanFromVelocity(velocity);
uint currentMotion = ae.Sequencer.CurrentMotion; uint currentMotion = ae.Sequencer.CurrentMotion;
@ -3344,10 +3421,7 @@ public sealed class GameWindow : IDisposable
// D2 (Commit A 2026-05-03): UPCYCLE diag — proves whether // D2 (Commit A 2026-05-03): UPCYCLE diag — proves whether
// ApplyServerControlledVelocityCycle is racing UpdateMotion-driven // ApplyServerControlledVelocityCycle is racing UpdateMotion-driven
// SetCycle for player-driven remotes. If this fires every ~100-200ms // SetCycle for non-player remotes (NPCs / monsters).
// during a Walk→Run press with `motion` flipping between buckets,
// H2 (UP-vs-UM race) is confirmed. UPs (5-10 Hz) would then
// perpetually overwrite the cycle the UM just set.
if (System.Environment.GetEnvironmentVariable("ACDREAM_REMOTE_VEL_DIAG") == "1") if (System.Environment.GetEnvironmentVariable("ACDREAM_REMOTE_VEL_DIAG") == "1")
{ {
System.Console.WriteLine( System.Console.WriteLine(
@ -3361,6 +3435,103 @@ public sealed class GameWindow : IDisposable
ae.Sequencer.SetCycle(style, plan.Motion, plan.SpeedMod); ae.Sequencer.SetCycle(style, plan.Motion, plan.SpeedMod);
} }
private void ApplyPlayerLocomotionRefinement(
uint serverGuid,
AnimatedEntity ae,
RemoteMotion rm,
System.Numerics.Vector3 velocity)
{
// UM grace: a fresh UM is authoritative.
double nowSec = (System.DateTime.UtcNow - System.DateTime.UnixEpoch).TotalSeconds;
double sinceUm = nowSec - rm.LastUMTime;
if (sinceUm < UmGraceSeconds) return;
uint currentMotion = ae.Sequencer!.CurrentMotion;
uint lowByte = currentMotion & 0xFFu;
// Forward-only refinement scope. WalkForward = 0x05, RunForward = 0x07.
// Sidestep (0x0F/0x10), WalkBackward (0x06), turns and any other
// motion (emote, attack, etc.) are left to UM-driven SetCycle.
const uint LowWalkForward = 0x05u;
const uint LowRunForward = 0x07u;
bool isForward = lowByte == LowWalkForward || lowByte == LowRunForward;
if (!isForward) return;
float horizSpeed = MathF.Sqrt(velocity.X * velocity.X + velocity.Y * velocity.Y);
// Hysteresis: stay in current bucket unless we cross the appropriate
// threshold. Below StopSpeed → don't refine (let UM Ready stop signal
// handle the stop transition; we don't want UP momentary 0-velocity
// to drop the cycle to Ready while the actor is mid-stride).
if (horizSpeed < AcDream.Core.Physics.ServerControlledLocomotion.StopSpeed)
return;
uint targetMotion;
float speedMod;
if (lowByte == LowRunForward)
{
if (horizSpeed < PlayerRunDemoteSpeed)
{
targetMotion = AcDream.Core.Physics.MotionCommand.WalkForward;
speedMod = MathF.Min(MathF.Max(
horizSpeed / AcDream.Core.Physics.MotionInterpreter.WalkAnimSpeed,
AcDream.Core.Physics.ServerControlledLocomotion.MinSpeedMod),
AcDream.Core.Physics.ServerControlledLocomotion.MaxSpeedMod);
}
else
{
targetMotion = AcDream.Core.Physics.MotionCommand.RunForward;
speedMod = MathF.Min(MathF.Max(
horizSpeed / AcDream.Core.Physics.MotionInterpreter.RunAnimSpeed,
AcDream.Core.Physics.ServerControlledLocomotion.MinSpeedMod),
AcDream.Core.Physics.ServerControlledLocomotion.MaxSpeedMod);
}
}
else
{
// currently WalkForward (0x05)
if (horizSpeed > PlayerRunPromoteSpeed)
{
targetMotion = AcDream.Core.Physics.MotionCommand.RunForward;
speedMod = MathF.Min(MathF.Max(
horizSpeed / AcDream.Core.Physics.MotionInterpreter.RunAnimSpeed,
AcDream.Core.Physics.ServerControlledLocomotion.MinSpeedMod),
AcDream.Core.Physics.ServerControlledLocomotion.MaxSpeedMod);
}
else
{
targetMotion = AcDream.Core.Physics.MotionCommand.WalkForward;
speedMod = MathF.Min(MathF.Max(
horizSpeed / AcDream.Core.Physics.MotionInterpreter.WalkAnimSpeed,
AcDream.Core.Physics.ServerControlledLocomotion.MinSpeedMod),
AcDream.Core.Physics.ServerControlledLocomotion.MaxSpeedMod);
}
}
// Skip the SetCycle if neither motion nor speedMod changed
// meaningfully — avoids replaying transition links every UP.
bool motionChanged = currentMotion != targetMotion
&& (currentMotion & 0xFFu) != (targetMotion & 0xFFu);
bool speedChanged = MathF.Abs(ae.Sequencer.CurrentSpeedMod - speedMod) > 0.05f;
if (!motionChanged && !speedChanged)
return;
if (System.Environment.GetEnvironmentVariable("ACDREAM_REMOTE_VEL_DIAG") == "1")
{
System.Console.WriteLine(
$"[UPCYCLE_PLAYER] guid={serverGuid:X8} "
+ $"|v|={horizSpeed:F2} cur=0x{currentMotion:X8} "
+ $"-> motion=0x{targetMotion:X8} speedMod={speedMod:F2} "
+ $"sinceUM={sinceUm:F2}s "
+ $"motionChg={motionChanged} speedChg={speedChanged}");
}
uint style = ae.Sequencer.CurrentStyle != 0
? ae.Sequencer.CurrentStyle
: 0x8000003Du;
ae.Sequencer.SetCycle(style, targetMotion, speedMod);
}
private void OnLivePositionUpdated(AcDream.Core.Net.WorldSession.EntityPositionUpdate update) private void OnLivePositionUpdated(AcDream.Core.Net.WorldSession.EntityPositionUpdate update)
{ {
// Phase A.1: track the most recently updated entity's landblock so the // Phase A.1: track the most recently updated entity's landblock so the
@ -3685,15 +3856,20 @@ public sealed class GameWindow : IDisposable
rmState.Body.Velocity = rmState.ServerVelocity; rmState.Body.Velocity = rmState.ServerVelocity;
} }
if (!IsPlayerGuid(update.Guid) if (rmState.HasServerVelocity
&& rmState.HasServerVelocity
&& _animatedEntities.TryGetValue(entity.Id, out var aeForVelocity)) && _animatedEntities.TryGetValue(entity.Id, out var aeForVelocity))
{ {
// #39 (2026-05-06): un-gated for player remotes — the
// function itself routes player remotes into the dedicated
// ApplyPlayerLocomotionRefinement path (forward-direction
// speed bucket only, with UM grace + hysteresis). Non-player
// remotes use the existing PlanFromVelocity path.
//
// D2 (Commit A 2026-05-03): tag whether the velocity feeding // D2 (Commit A 2026-05-03): tag whether the velocity feeding
// ApplyServerControlledVelocityCycle is wire-explicit (rare for // ApplyServerControlledVelocityCycle is wire-explicit (rare for
// player remotes — ACE almost never sets HasVelocity on player // player remotes — ACE almost never sets HasVelocity on player
// UPs) or synthesized from position deltas (the common case). // UPs) or synthesized from position deltas (the common case).
// Pairs with the [UPCYCLE] line printed inside the call. // Pairs with the [UPCYCLE]/[UPCYCLE_PLAYER] line printed inside.
if (System.Environment.GetEnvironmentVariable("ACDREAM_REMOTE_VEL_DIAG") == "1") if (System.Environment.GetEnvironmentVariable("ACDREAM_REMOTE_VEL_DIAG") == "1")
{ {
string velSrc = update.Velocity is null ? "synth" : "wire"; string velSrc = update.Velocity is null ? "synth" : "wire";