diff --git a/cmd/expedition-sim/main.go b/cmd/expedition-sim/main.go
index 78a56e8..f5eae29 100644
--- a/cmd/expedition-sim/main.go
+++ b/cmd/expedition-sim/main.go
@@ -32,6 +32,7 @@ func main() {
 		zone    = flag.String("zone", "goblin_warrens", "zone id (single-run mode)")
 		bank    = flag.Float64("bank", 1000, "starting coin balance — must cover outfitting")
 		cap     = flag.Int("cap", 50, "max autopilot bursts per expedition (each = up to autopilotRoomCap rooms)")
+		days    = flag.Int("days", 0, "stop after N synthetic day rollovers (0 = unbounded; the -cap safety net still applies)")
 		dataDir = flag.String("data", "", "data dir for the temp sqlite db (default: OS tempdir; ignored in matrix mode)")
 		userTag = flag.String("user", "@sim:expedition", "synthetic user id (single-run mode)")
 		logFlag = flag.Bool("log", true, "include per-row expedition log in output (single-run default true; matrix default false)")
@@ -65,14 +66,14 @@ func main() {
 				includeLog = *logFlag
 			}
 		})
-		runMatrix(*classes, *levels, *zones, *runs, *bank, *cap, includeLog)
+		runMatrix(*classes, *levels, *zones, *runs, *bank, *cap, *days, includeLog)
 		return
 	}
 
-	runSingle(*class, *level, *zone, *userTag, *dataDir, *bank, *cap, *logFlag)
+	runSingle(*class, *level, *zone, *userTag, *dataDir, *bank, *cap, *days, *logFlag)
 }
 
-func runSingle(class string, level int, zone, userTag, dataDir string, bank float64, cap int, includeLog bool) {
+func runSingle(class string, level int, zone, userTag, dataDir string, bank float64, cap, days int, includeLog bool) {
 	dir := dataDir
 	if dir == "" {
 		var err error
@@ -83,7 +84,7 @@ func runSingle(class string, level int, zone, userTag, dataDir string, bank floa
 		defer os.RemoveAll(dir)
 	}
 
-	res, err := runOne(dir, id.UserID(userTag), plugin.DnDClass(class), level, plugin.ZoneID(zone), bank, cap)
+	res, err := runOne(dir, id.UserID(userTag), plugin.DnDClass(class), level, plugin.ZoneID(zone), bank, cap, days)
 	if err != nil {
 		if res != nil {
 			if !includeLog {
@@ -99,7 +100,7 @@ func runSingle(class string, level int, zone, userTag, dataDir string, bank floa
 	emitIndented(res)
 }
 
-func runMatrix(classes, levels, zones string, runs int, bank float64, cap int, includeLog bool) {
+func runMatrix(classes, levels, zones string, runs int, bank float64, cap, days int, includeLog bool) {
 	cs := splitNonEmpty(classes)
 	ls := parseLevels(levels)
 	zs := splitNonEmpty(zones)
@@ -116,7 +117,7 @@ func runMatrix(classes, levels, zones string, runs int, bank float64, cap int, i
 						fail("mkdir temp:", err)
 					}
 					uid := id.UserID(fmt.Sprintf("@sim:%s-l%d-%s-%d", c, lv, z, r))
-					res, runErr := runOne(dir, uid, plugin.DnDClass(c), lv, plugin.ZoneID(z), bank, cap)
+					res, runErr := runOne(dir, uid, plugin.DnDClass(c), lv, plugin.ZoneID(z), bank, cap, days)
 					if res != nil && !includeLog {
 						res.Log = nil
 					}
@@ -139,7 +140,7 @@ func runMatrix(classes, levels, zones string, runs int, bank float64, cap int, i
 	}
 }
 
-func runOne(dataDir string, uid id.UserID, class plugin.DnDClass, level int, zone plugin.ZoneID, bank float64, cap int) (*plugin.SimResult, error) {
+func runOne(dataDir string, uid id.UserID, class plugin.DnDClass, level int, zone plugin.ZoneID, bank float64, cap, days int) (*plugin.SimResult, error) {
 	runner, err := plugin.NewSimRunner(dataDir)
 	if err != nil {
 		return nil, fmt.Errorf("init runner: %w", err)
@@ -150,7 +151,7 @@ func runOne(dataDir string, uid id.UserID, class plugin.DnDClass, level int, zon
 		return nil, fmt.Errorf("build character: %w", err)
 	}
 	runner.Euro.Credit(uid, bank, "expedition-sim bankroll")
-	return runner.RunExpedition(uid, zone, cap)
+	return runner.RunExpedition(uid, zone, cap, days)
 }
 
 func emitIndented(res *plugin.SimResult) {
diff --git a/gogobee_long_expedition_plan.md b/gogobee_long_expedition_plan.md
index 5c988ea..19b3b4b 100644
--- a/gogobee_long_expedition_plan.md
+++ b/gogobee_long_expedition_plan.md
@@ -141,8 +141,9 @@ Each successful background walk now logs a `walk` entry (`appendExpeditionLog(..
 
 **D7-b (shipped 2026-05-27):** `SimRunner.RunExpedition` now drives the production camp scheduler under a synthetic clock (`simWalkInterval = autoRunCooldown`, 2h per walk). After every soft-stop walk it calls `maybeAutoCamp(exp, simNow)`; `stopBossSafety` routes to `pitchBossSafetyCamp(exp, simNow)`. The helpers (`applyAutoCamp` / `applyAutoCampBossSafety`) advance `simNow` past `minAutoCampDwell` (4h) and break the auto-pitched camp via `breakAutoCampIfDue` so the next walk proceeds. `maybeAutoCamp`, `pitchAutopilotCamp`, and `pitchBossSafetyCamp` gained a `now time.Time` parameter (the only prod caller, `tryAutoRun`, still passes `time.Now().UTC()`). Effect: HP-low mid-day rests, multi-region base-camp waypoints, Night-camp rollovers, and boss-safety holds all fire under the sim — the D7-a `tickEventAnchoredRollover` shortcut is no longer used by RunExpedition (kept on TickDay for tests + the pre-cutoff legacy path). Coverage in `expedition_sim_test.go`: Night-camp day advance, HP-low mid-day rest, boss-safety force-pitch, no-op when neither trigger fires.
 
-**Remaining work (D7-c+):**
-- `cmd/expedition-sim` extensions: multi-day mode CLI flag (`-days` / per-day SU/HP/threat snapshots in SimResult).
+**D7-c (shipped 2026-05-27):** `cmd/expedition-sim` gained a `-days N` flag — when set, `RunExpedition` exits with `Outcome="day_capped"` after the Nth synthetic day rollover; 0 (default) is unbounded and only the existing `-cap` walk safety net applies. `SimResult` gained `DaySnapshots []SimDaySnapshot` ({Day, HPCurrent, HPMax, Supplies, Threat, Rooms}), captured at expedition start (Day 0), after every `applyAutoCamp`/`applyAutoCampBossSafety` Night-camp rollover, and one final end-of-run entry (reads `getExpedition(mostRecentExpeditionID(...))` when the row already extracted so closed runs still close their trajectory). `RunExpedition` signature picked up the `maxDays int` parameter; sole caller is the CLI. Coverage: `TestSimRunner_CaptureDaySnapshot_PopulatesFields` exercises the helper in isolation (HP from the live character row, SU/threat/day from the live expedition, Rooms from `res.Rooms`). Unblocks empirical D5-d retune of `phase5BDailyBurnRatePct` against per-day SU draws.
+
+**Remaining work (D7-d+):**
 - Re-run the class win-rate corpus (cross-link `project_class_balance`, `project_j2_sim_artifact`).
 - Re-check trailers (bard/cleric per `project_j1_post_sweep_findings`) — autopilot camp pacing may relieve their HP-cliff issue.
 - D5-d retune of `DailyBurn` / `phase5BDailyBurnRatePct` against measured day-counts.
diff --git a/internal/plugin/expedition_sim.go b/internal/plugin/expedition_sim.go
index 6f8b109..56e3e3d 100644
--- a/internal/plugin/expedition_sim.go
+++ b/internal/plugin/expedition_sim.go
@@ -282,7 +282,25 @@ type SimResult struct {
 	// without re-running the matrix. Populated from combat_sessions
 	// rows + their TurnLog at end-of-run.
 	Combats []SimCombatSummary
-	Log     []SimLogEntry
+	// DaySnapshots traces HP/SU/threat/rooms at every day rollover
+	// (Night camp) plus the start (Day 0) and the final state. Used by
+	// D7-c long-expedition baselining to see how the trajectory bends
+	// across multi-day runs without scrubbing the log.
+	DaySnapshots []SimDaySnapshot
+	Log          []SimLogEntry
+}
+
+// SimDaySnapshot is a point-in-time projection of the sim state at a
+// day-rollover boundary. Day 0 is captured at expedition start; every
+// subsequent entry lands right after a Night camp lands (CurrentDay
+// already incremented). A final entry is appended at end-of-run.
+type SimDaySnapshot struct {
+	Day       int
+	HPCurrent int
+	HPMax     int
+	Supplies  float32
+	Threat    int
+	Rooms     int // cumulative autopilot rooms walked at snapshot time
 }
 
 // SimCombatSummary is a compact per-fight trace: the entry stats, the
@@ -366,9 +384,14 @@ const simWalkInterval = autoRunCooldown
 // walkCap bounds the number of autopilot bursts as a safety net. Each
 // burst walks up to autopilotRoomCap rooms.
 //
+// maxDays, when > 0, stops the run once res.DayTicks reaches that count
+// — used by D7-c long-expedition baselining to bound multi-day runs by
+// synthetic day count rather than walk count. 0 leaves the run
+// unbounded by days (the walkCap safety net still applies).
+//
 // Pre-state: uid must own a synthetic character via BuildCharacter and
 // have a coin balance sufficient for outfitting (caller's responsibility).
-func (s *SimRunner) RunExpedition(uid id.UserID, zoneID ZoneID, walkCap int) (*SimResult, error) {
+func (s *SimRunner) RunExpedition(uid id.UserID, zoneID ZoneID, walkCap, maxDays int) (*SimResult, error) {
 	c, err := LoadDnDCharacter(uid)
 	if err != nil || c == nil {
 		return nil, fmt.Errorf("LoadDnDCharacter: %w", err)
@@ -392,6 +415,9 @@ func (s *SimRunner) RunExpedition(uid id.UserID, zoneID ZoneID, walkCap int) (*S
 		return res, fmt.Errorf("expedition did not persist after start")
 	}
 	res.SUStart = exp.Supplies.Current
+	// Day-0 baseline so the snapshot stream always opens with a known
+	// starting state, even if the run halts before the first rollover.
+	s.captureDaySnapshot(res, exp, uid)
 
 	// Synthetic clock — anchored on the expedition's real start_date so
 	// nightCampWindow / nightSafetyNet comparisons against LastBriefingAt
@@ -500,11 +526,20 @@ func (s *SimRunner) RunExpedition(uid id.UserID, zoneID ZoneID, walkCap int) (*S
 			}
 			if advanced {
 				res.DayTicks++
+				if fresh2, _ := getActiveExpedition(uid); fresh2 != nil {
+					s.captureDaySnapshot(res, fresh2, uid)
+				}
 			}
 			if exp, _ = getActiveExpedition(uid); exp == nil {
 				res.Outcome = "extracted"
 				i = walkCap
 			}
+			if maxDays > 0 && res.DayTicks >= maxDays {
+				if res.Outcome == "" {
+					res.Outcome = "day_capped"
+				}
+				i = walkCap
+			}
 		default:
 			// stopOK / stopPreflight / stopHarvestCombat — soft stops.
 			// Run the same camp scheduler the production autorun fires
@@ -526,12 +561,21 @@ func (s *SimRunner) RunExpedition(uid id.UserID, zoneID ZoneID, walkCap int) (*S
 			}
 			if advanced {
 				res.DayTicks++
+				if fresh2, _ := getActiveExpedition(uid); fresh2 != nil {
+					s.captureDaySnapshot(res, fresh2, uid)
+				}
 			}
 			// maybeAutoCamp's drift step may have force-extracted (starvation).
 			if exp, _ = getActiveExpedition(uid); exp == nil {
 				res.Outcome = "extracted"
 				i = walkCap
 			}
+			if maxDays > 0 && res.DayTicks >= maxDays {
+				if res.Outcome == "" {
+					res.Outcome = "day_capped"
+				}
+				i = walkCap
+			}
 		}
 	}
 	if res.Outcome == "" {
@@ -557,9 +601,38 @@ func (s *SimRunner) RunExpedition(uid id.UserID, zoneID ZoneID, walkCap int) (*S
 	}
 	res.YieldCount, res.YieldsByName = simMaterialYields(uid)
 	res.Combats = simCombatSummaries(uid)
+	// Final snapshot. Re-read the expedition so closed-run state is
+	// visible (extracted runs return nil from getActiveExpedition; the
+	// row is still on disk via mostRecentExpeditionID). If the
+	// expedition row is gone we synthesize from the cached SU/threat
+	// already on res so the snapshot stream always closes.
+	if exp2, _ := getActiveExpedition(uid); exp2 != nil {
+		s.captureDaySnapshot(res, exp2, uid)
+	} else if past := mostRecentExpeditionID(uid); past != "" {
+		if exp3, _ := getExpedition(past); exp3 != nil {
+			s.captureDaySnapshot(res, exp3, uid)
+		}
+	}
 	return res, nil
 }
 
+// captureDaySnapshot appends a SimDaySnapshot reflecting current state.
+// HP is read from the live character row; SU/threat/day from the live
+// expedition. Rooms is the running res.Rooms counter.
+func (s *SimRunner) captureDaySnapshot(res *SimResult, exp *Expedition, uid id.UserID) {
+	snap := SimDaySnapshot{
+		Day:      exp.CurrentDay,
+		Supplies: exp.Supplies.Current,
+		Threat:   exp.ThreatLevel,
+		Rooms:    res.Rooms,
+	}
+	if c, _ := LoadDnDCharacter(uid); c != nil {
+		snap.HPCurrent = c.HPCurrent
+		snap.HPMax = c.HPMax
+	}
+	res.DaySnapshots = append(res.DaySnapshots, snap)
+}
+
 // simCombatSummaries pulls every combat_sessions row for uid and folds
 // its TurnLog into a SimCombatSummary. AC values are inferred from the
 // RollAgainst column on attack events (the engine writes the defender's
diff --git a/internal/plugin/expedition_sim_test.go b/internal/plugin/expedition_sim_test.go
index d229207..960abc9 100644
--- a/internal/plugin/expedition_sim_test.go
+++ b/internal/plugin/expedition_sim_test.go
@@ -293,3 +293,51 @@ func TestSimRunner_TickDay_EventAnchoredLowSupplies(t *testing.T) {
 		t.Errorf("CurrentDay = %d, want >= 2", got.CurrentDay)
 	}
 }
+
+// D7-c: captureDaySnapshot must record the current expedition's day,
+// supplies, and threat plus the character's live HP into res.DaySnapshots.
+// Used by RunExpedition to trace state at every day rollover for
+// long-expedition baselining; verified here in isolation since
+// RunExpedition end-to-end isn't covered by package tests.
+func TestSimRunner_CaptureDaySnapshot_PopulatesFields(t *testing.T) {
+	setupZoneRunTestDB(t)
+	uid := id.UserID("@sim-snap:example")
+	campTestCharacter(t, uid, 3)
+	defer cleanupExpeditions(uid)
+
+	exp, err := startExpedition(uid, ZoneGoblinWarrens, "",
+		ExpeditionSupplies{Current: 12, Max: 20, DailyBurn: 2, HarshMod: 1})
+	if err != nil {
+		t.Fatal(err)
+	}
+	exp.CurrentDay = 3
+	exp.ThreatLevel = 7
+	if err := updateSupplies(exp.ID, exp.Supplies); err != nil {
+		t.Fatal(err)
+	}
+	c, _ := LoadDnDCharacter(uid)
+
+	sim := &SimRunner{P: &AdventurePlugin{}}
+	res := &SimResult{Rooms: 9}
+	sim.captureDaySnapshot(res, exp, uid)
+
+	if len(res.DaySnapshots) != 1 {
+		t.Fatalf("DaySnapshots len = %d, want 1", len(res.DaySnapshots))
+	}
+	snap := res.DaySnapshots[0]
+	if snap.Day != 3 {
+		t.Errorf("Day = %d, want 3", snap.Day)
+	}
+	if snap.Supplies != 12 {
+		t.Errorf("Supplies = %v, want 12", snap.Supplies)
+	}
+	if snap.Threat != 7 {
+		t.Errorf("Threat = %d, want 7", snap.Threat)
+	}
+	if snap.Rooms != 9 {
+		t.Errorf("Rooms = %d, want 9", snap.Rooms)
+	}
+	if snap.HPCurrent != c.HPCurrent || snap.HPMax != c.HPMax {
+		t.Errorf("HP = %d/%d, want %d/%d", snap.HPCurrent, snap.HPMax, c.HPCurrent, c.HPMax)
+	}
+}