Add aura caster + non-player expiration to C_UnitAuras

Populate AuraData sourceUnit/sourceGUID and non-player expirationTime by
co-hooking SMSG_SPELL_GO (FUN_SPELL_GO) and caching (targetGuid, spellId)
-> caster + expiration. The vanilla unit aura array stores only spell IDs;
the SpellGo packet is the only place the client sees an aura's caster and a
server-authoritative duration. We parse the engine packet ourselves, so
this is self-sufficient (no nampower dependency) -- when nampower is loaded
we simply co-hook the same site.

sourceGUID is a ClassicAPI extension (raw "0x..." string), set whenever a
caster is known including when sourceUnit is nil; stable across the session,
unlike the volatile nameplate token, and usable as a unit token under
SuperWoW.

Also consolidate the local-player-GUID read into Unit::Identity::PlayerGuid()
(was duplicated inline in four files) and expose Unit::Identity GuidForToken
/ TokenFromGUID for reuse.

Author: brues-code

docs/API.md

@@ -9271,20 +9271,48 @@ selects.
 | `isHelpful` | boolean | true for slot < 32 |
 | `isHarmful` | boolean | true for slot >= 32 |
 | `duration` | number | base applied duration in seconds, looked up via `Spell.dbc → SpellDuration.dbc` with level scaling. Talent / glyph duration extensions (Improved PW:F, etc.) aren't reflected here — those are baked into `expirationTime` on the caster's side. Returns 0 for spells flagged "no duration" (passives, paladin auras, infinite buffs) |
-| `expirationTime` | number | populated for `unit == "player"` (read from the engine's player-buff table at `0x00BC6040`; same data `GetPlayerBuffTimeLeft` returns). Always `0` for all other units — vanilla server only broadcasts cast/duration for the local player's own auras. `expirationTime - GetTime()` gives the true remaining time (including any talent extensions) |
+| `expirationTime` | number | for `unit == "player"`, read from the engine's player-buff table at `0x00BC6040` (same data `GetPlayerBuffTimeLeft` returns). For any other unit, taken from the `Aura::Source` cache (cast time + duration captured from `SMSG_SPELL_GO`; see below). `0` when neither source has it. `expirationTime - GetTime()` gives the true remaining time |
+| `sourceUnit` | string | unit token of the caster (`"player"`, `"raid7"`, `"nameplate1"`, …), resolved from the `Aura::Source` cache. `nil` if the cast wasn't observed or the caster maps to no current token |
+| `sourceGUID` | string | caster's `"0x…"` GUID string from the same cache. **ClassicAPI extension — not a retail `AuraData` field.** Set whenever a caster is known, including when `sourceUnit` is `nil` (caster left token range). Stable for the session, unlike the volatile nameplate token; doubles as a unit token under SuperWoW. `nil` on a cache miss |
 | `charges` / `maxCharges` | number | always `0` — vanilla has stacks, not charges |
 | `timeMod` | number | always `1` — vanilla has no haste-affected auras |
 | `isStealable`, `isBossAura`, `isFromPlayerOrPlayerPet`, `isNameplateOnly`, `nameplateShowAll`, `nameplateShowPersonal`, `canApplyAura`, `shouldConsolidate`, `isRaid` | boolean | always `false` — modern UI concepts vanilla doesn't have |
-| `sourceUnit`, `auraInstanceID`, `points` | (absent) | omitted from the table — Lua read yields nil, matching modern semantics for "field doesn't apply" |
+| `auraInstanceID`, `points` | (absent) | omitted from the table — Lua read yields nil, matching modern semantics for "field doesn't apply" |
 
 ### Filter parsing
 
 The optional `filter` string is a pipe-separated set of upper-case
 tokens, matching modern syntax (`"HELPFUL"`, `"HARMFUL"`,
 `"HELPFUL|PLAYER"`, etc.). Only `HELPFUL` (default) and `HARMFUL`
 are honored on vanilla; other tokens (`PLAYER` / `RAID` /
-`CANCELABLE` / `INCLUDE_NAME_PLATE_ONLY`) are accepted but no-op —
-they'd need source-GUID tracking or systems vanilla doesn't have.
+`CANCELABLE` / `INCLUDE_NAME_PLATE_ONLY`) are accepted but no-op.
+(`PLAYER` is now technically derivable — `sourceGUID` vs. the player
+GUID — but filtering on it isn't wired in yet; `RAID` / nameplate
+flags still need systems vanilla doesn't have.)
+
+### Caster & timing (`Aura::Source`)
+
+`sourceUnit`, `sourceGUID`, and non-player `expirationTime` come from a
+client-side cache that vanilla itself can't provide: the unit aura array
+stores only spell IDs — never the caster, and no cast/expiration timing for
+anyone but the local player. The one place the client sees an aura's caster
++ a server-authoritative duration is the `SMSG_SPELL_GO` packet at cast
+time. `Aura::Source` co-hooks the engine's `SpellGo` handler
+(`FUN_SPELL_GO`, `0x006E7A70`), parses the hit-target list, and caches
+`(targetGuid, spellId) → { casterGuid, expirationMs }`. `Push` then keys
+into it by the unit's GUID + the aura's spell ID.
+
+Implications:
+
+- **Best-effort.** Only auras applied *after* login (whose cast we
+  observed) carry caster/expiration; auras already up when you logged in,
+  or applied by mechanisms that don't emit `SMSG_SPELL_GO`, leave the
+  defaults (`sourceUnit`/`sourceGUID` nil, non-player `expirationTime` 0).
+- **No nampower dependency.** We parse the engine packet ourselves. nampower
+  (which hooks the same function) need not be loaded; when it is, we simply
+  co-hook the site.
+- Entries are evicted once their timed aura elapses, so the cache stays
+  bounded; infinite-duration auras persist until overwritten under load.
 
 ### `C_UnitAuras.GetAuraDataByIndex(unit, index [, filter])`
 

src/Offsets.h

@@ -682,6 +682,19 @@ enum Offsets {
     OFF_SPELLDURATION_PER_LEVEL_MS = 0x08,
     OFF_SPELLDURATION_MAX_MS = 0x0C,
 
+    // `SMSG_SPELL_GO` inner handler — `void __fastcall(uint64_t *itemGUID,
+    // uint64_t *casterGUID, uint32_t spellId, CDataStore *packet)`. The
+    // engine has already decoded item/caster/spell into args; the packet
+    // read cursor sits at the post-header body (castFlags, hit/missed
+    // target lists, target mask). This is the ONLY place the client sees
+    // an aura's *caster* — the unit aura array stores spell IDs but never
+    // who applied them. `Aura::Source` co-hooks this (alongside nampower,
+    // which detours the same function) to cache `(targetGuid, spellId) →
+    // casterGuid` for `C_UnitAuras` sourceUnit + non-player expiration.
+    // Packet layout mirrored from nampower's SpellGoHook (verified on the
+    // same Octo/Turtle 1.12.1 client). Per-cast frequency, not per-frame.
+    FUN_SPELL_GO = 0x006E7A70,
+
     // CGPlayer-side sub-struct, allocated for any player-controlled
     // unit (local self, target, party, raid, inspect targets — all of
     // them). Holds player-specific data that's *not* in the broadcast

src/aura/Data.cpp

@@ -15,7 +15,10 @@
 
 #include "Game.h"
 #include "Offsets.h"
+#include "aura/Source.h"
 #include "dbc/Lookup.h"
+#include "guid/Guid.h"
+#include "unit/Identity.h"
 
 #include <cstdint>
 #include <cstring>
@@ -38,6 +41,20 @@ const uint8_t *Descriptor(const uint8_t *unit) {
         unit + Offsets::OFF_CGUNIT_OBJECT_FIELDS);
 }
 
+// The unit's 64-bit GUID, read through the pointer at `unit + 0x08` to an
+// instance block whose first 8 bytes are the GUID (verified in
+// `Script_GetInventoryItemLink`; see `OFF_UNIT_GUID_PTR`). Used to key into
+// the `Aura::Source` caster/expiration cache. 0 if unresolved.
+uint64_t UnitGuid(const uint8_t *unit) {
+    if (unit == nullptr)
+        return 0;
+    const uint8_t *block = *reinterpret_cast<const uint8_t *const *>(
+        unit + Offsets::OFF_UNIT_GUID_PTR);
+    if (block == nullptr)
+        return 0;
+    return *reinterpret_cast<const uint64_t *>(block);
+}
+
 const uint8_t *SpellRecord(uint32_t spellID) {
     return DBC::Record(Offsets::VAR_SPELL_RECORDS,
                        Offsets::VAR_SPELL_RECORD_COUNT, spellID);
@@ -374,8 +391,44 @@ void Push(void *L, const uint8_t *unit, int slot) {
         if (entry != nullptr)
             expirationTime = PlayerBuffExpirationSeconds(entry);
     }
+
+    // Caster + non-player expiration from the SMSG_SPELL_GO cache
+    // (`Aura::Source`), captured at cast time. The vanilla descriptor has
+    // neither. `sourceUnit` applies to any unit; `expirationTime` only
+    // fills in here when the player-buff table above didn't — that table is
+    // authoritative for the player's own auras, the cache covers everyone
+    // else. Both are best-effort: a miss (aura predates login, or the cast
+    // wasn't observed) leaves the modern-truthful defaults untouched.
+    const char *sourceUnit = nullptr;
+    const char *sourceGUID = nullptr;
+    char tokenBuf[32];
+    char guidBuf[Guid::STRING_SIZE];
+    if (spellID != 0) {
+        uint64_t casterGuid = 0;
+        uint32_t expMs = 0;
+        if (Aura::Source::Get(UnitGuid(unit), spellID, &casterGuid, &expMs)) {
+            if (expirationTime == 0.0 && expMs != 0)
+                expirationTime = static_cast<double>(expMs) * 0.001;
+            if (casterGuid != 0) {
+                // `sourceUnit` is a token (nil when the caster maps to no
+                // current token); `sourceGUID` is the raw "0x..." GUID and
+                // is set whenever we have a caster — a ClassicAPI extension
+                // (not in retail AuraData) that survives the caster leaving
+                // token range and doubles as a unit token under SuperWoW.
+                sourceUnit = Unit::Identity::TokenFromGUID(
+                    casterGuid, tokenBuf, sizeof tokenBuf);
+                sourceGUID = Guid::FormatAsString(casterGuid, guidBuf,
+                                                  sizeof guidBuf);
+            }
+        }
+    }
+
     Game::Lua::SetFieldNumber(L, "duration", duration);
     Game::Lua::SetFieldNumber(L, "expirationTime", expirationTime);
+    if (sourceUnit != nullptr)
+        Game::Lua::SetFieldString(L, "sourceUnit", sourceUnit);
+    if (sourceGUID != nullptr)
+        Game::Lua::SetFieldString(L, "sourceGUID", sourceGUID);
     Game::Lua::SetFieldNumber(L, "charges", 0);
     Game::Lua::SetFieldNumber(L, "maxCharges", 0);
     Game::Lua::SetFieldNumber(L, "timeMod", 1);
@@ -391,10 +444,11 @@ void Push(void *L, const uint8_t *unit, int slot) {
     Game::Lua::SetFieldBool(L, "shouldConsolidate", false);
     Game::Lua::SetFieldBool(L, "isRaid", false);
 
-    // `sourceUnit`, `auraInstanceID`, `points` deliberately omitted
-    // — modern returns nil for those when they don't apply, and
-    // Lua reading a missing key yields nil, so the table doesn't
-    // need an explicit entry.
+    // `sourceUnit` / `sourceGUID` are set above when the `Aura::Source`
+    // cache has a caster for this aura; left unset (→ nil) on a miss.
+    // `auraInstanceID` and `points` are deliberately omitted — modern
+    // returns nil for those when they don't apply, and Lua reading a
+    // missing key yields nil, so the table doesn't need an explicit entry.
 }
 
 } // namespace Aura::Data

src/aura/Data.h

@@ -85,12 +85,18 @@ const char *DispelName(uint32_t dispelTypeID);
 //
 // Populates these fields with real data:
 //   name, icon, applications, spellId, dispelName,
-//   isHelpful, isHarmful, timeMod
+//   isHelpful, isHarmful, timeMod, duration
+//
+// And these from the `Aura::Source` SMSG_SPELL_GO cache when available
+// (else their inapplicable default):
+//   expirationTime (player: engine buff table; others: cache; 0 on miss),
+//   sourceUnit     (caster token from the cache; nil on miss),
+//   sourceGUID     (caster "0x..." GUID string; nil on miss — a ClassicAPI
+//                   extension, not in retail AuraData)
 //
 // And these with vanilla-truthful defaults (matches modern's
 // "field present but inapplicable" semantics):
-//   duration=0, expirationTime=0, charges=0, maxCharges=0,
-//   sourceUnit=nil, auraInstanceID=nil, points=nil,
+//   charges=0, maxCharges=0, auraInstanceID=nil, points=nil,
 //   isStealable=false, isBossAura=false, isFromPlayerOrPlayerPet=false,
 //   isNameplateOnly=false, nameplateShowAll=false,
 //   nameplateShowPersonal=false, canApplyAura=false,