diff --git a/docs/logs/engineering-log.md b/docs/logs/engineering-log.md
index 9b064f0c..ad8ff7ee 100644
--- a/docs/logs/engineering-log.md
+++ b/docs/logs/engineering-log.md
@@ -104,6 +104,22 @@
   `./scripts/test-regression.sh` passed with 85.6% total coverage and zero
   uncovered functions.
 
+## 2026-07-30 (Subscriber-Pinned Retention Quota — Issue #1048)
+
+- Symptom: hosted race CI could not subscribe to a just-completed extra run
+  because pruning had already removed it.
+- Cause: a persisted terminal run with an active subscriber consumed the
+  retention quota despite being ineligible for deletion.
+- Planned fix: compute pruning pressure only from persisted, terminal,
+  zero-subscriber candidates; pinned states remain protected exceptions until
+  cancellation re-runs pruning.
+- Verification contract: focused/adjacent normal and race stress, harness
+  normal/race, full regression, and GitHub required checks.
+- Result: focused normal/race passed at `-count=100`, adjacent pruning
+  normal/race passed at `-count=20`, the complete harness package passed
+  normal/race, and the final full regression passed with 85.6% coverage and
+  zero uncovered functions.
+
 ## 2026-07-30 (Workflow Subscription Cancellation Test — Issue #1035)
 
 - Symptom: the full race gate failed in
diff --git a/docs/logs/long-term-thinking-log.md b/docs/logs/long-term-thinking-log.md
index 39fe2fc5..a7729e92 100644
--- a/docs/logs/long-term-thinking-log.md
+++ b/docs/logs/long-term-thinking-log.md
@@ -89,6 +89,21 @@
   assertion and cleared focused stress, package stress, normal, race, and
   coverage verification.
 
+## 2026-07-30 (Subscriber-Pinned Retention Quota — Issue #1048)
+
+- Command intent: repair the run-retention defect exposed while proving the
+  cron/callback GUI merge chain.
+- User intent: keep API, TUI, and GUI conversation streams reliable under real
+  concurrent lifecycle pressure, not merely green in isolated tests.
+- Success definition: pinned runs stay readable, newly completed runs remain
+  subscribable, unpinned history stays bounded, and cancellation reclaims the
+  exception.
+- Guardrails: issue-first isolated worktree, preserve persistent records and
+  terminal ordering, no config or wire changes.
+- Outcome: pruning pressure now comes only from drainable terminal candidates;
+  pinned states remain temporary exceptions, subscriber cancellation still
+  triggers cleanup, and all focused through full gates are green.
+
 ## 2026-07-30 (Workflow Subscription Cancellation Test — Issue #1035)
 
 - Command intent: clear the race-gate blocker exposed while verifying the
diff --git a/docs/plans/2026-07-30-issue-1048-pinned-retention-quota-impact-map.md b/docs/plans/2026-07-30-issue-1048-pinned-retention-quota-impact-map.md
new file mode 100644
index 00000000..e1f5f4ef
--- /dev/null
+++ b/docs/plans/2026-07-30-issue-1048-pinned-retention-quota-impact-map.md
@@ -0,0 +1,76 @@
+# Cross-Surface Impact Map: Issue #1048 Pinned Retention Quota
+
+## Task
+
+- Task / issue: exclude subscriber-pinned terminal states from the drainable
+  retention quota, #1048.
+- Plan: `2026-07-30-issue-1048-pinned-retention-quota-plan.md`.
+- Owner: Codex.
+- Status: implemented and fully verified locally; hosted checks pending.
+
+## Current Ownership, Callers, and Data Flow
+
+- Entry: terminal completion/failure/cancellation calls
+  `pruneCompletedRuns`.
+- Source of truth: `Runner.runs`; only persisted terminal states with zero
+  subscribers are deletion candidates.
+- Current calculation: all persisted terminal states increment
+  `terminalCount`, while only drainable states enter `candidates`.
+- Caller impact: `StartRun` followed by `Subscribe` can lose a fast run when a
+  pinned terminal state consumes the quota.
+
+## Config, API, CLI, and Tools
+
+- Config: retain `MaxCompletedRetention` and its default.
+- API: `Subscribe` no longer loses the newest drainable run solely because a
+  different run remains pinned.
+- CLI/TUI/tools: wire shapes and commands unchanged.
+
+## Persistence and Compatibility
+
+- Persistent Store records/events: unchanged and never deleted by this path.
+- Schemas/migrations/caches: none.
+- Compatibility: memory may hold configured drainable states plus pinned
+  exceptions, matching the existing after-subscribers-drain documentation.
+
+## Lifecycle, Security, and Reliability
+
+- Concurrency: existing Runner lock remains the sole synchronization boundary.
+- Cleanup: subscriber cancellation re-runs pruning.
+- Auth/privacy/secrets: none.
+- Failure/recovery: persistent store fallback remains available.
+
+## Product and Integration Surfaces
+
+- Harness/API: fast completed runs remain subscribable under retention pressure.
+- TUI/macOS GUI: run-scoped streams avoid a transient `run not found` failure.
+- Conversation-level callback/cron streams: wire behavior unchanged; their run
+  state remains stable while related run subscribers are pinned.
+- Providers/web/accessibility: none.
+
+## Deployment and Operations
+
+- Deployment/migration/flags: none.
+- Observability: fewer premature `run not found` errors.
+- Rollback: revert if unpinned candidates exceed the configured cap after
+  pruning or cancellation fails to reclaim pinned state.
+
+## Regression Tests
+
+- Red: hosted `collect extra run 2 events: run ... not found`.
+- Green: focused normal/race `-count=100`.
+- Controls: active subscriber remains pinned; the newest unpinned run remains
+  available; older unpinned runs prune; cancellation restores the cap.
+- Full: adjacent pruning, harness normal/race, and
+  `./scripts/test-regression.sh`.
+
+## Documentation and Handoff
+
+- Update engineering log, long-term log, plan, impact map, and plans index.
+- No public docs because behavior now matches the existing config contract.
+
+## Warning Check
+
+- Retention semantics and run-stream consumers are the only affected surfaces;
+  persistence, conversation mirrors, tools, providers, and schemas were
+  searched and are unchanged.
diff --git a/docs/plans/2026-07-30-issue-1048-pinned-retention-quota-plan.md b/docs/plans/2026-07-30-issue-1048-pinned-retention-quota-plan.md
new file mode 100644
index 00000000..9389f91c
--- /dev/null
+++ b/docs/plans/2026-07-30-issue-1048-pinned-retention-quota-plan.md
@@ -0,0 +1,65 @@
+# Plan: Exclude Subscriber-Pinned Runs from the Drainable Retention Quota
+
+## Context
+
+- Governing GitHub issue: #1048.
+- Problem: persisted terminal runs with active subscribers count toward
+  `MaxCompletedRetention` even though pruning cannot delete them. Under pressure
+  a just-completed run can be deleted before its caller subscribes.
+- Red evidence: hosted race CI failed
+  `TestRunner_PruneKeepsCompletedRunWithActiveSubscriber` because an extra run
+  was already missing at subscription time.
+- Constraint: preserve pinned-run protection, persistent records, and bounded
+  retention after subscribers drain.
+
+## Scope
+
+- In scope: count only eligible zero-subscriber terminal candidates when
+  calculating pruning pressure.
+- Out of scope: conversation retention, store deletion, subscription delivery,
+  terminal persistence, and configuration shape/defaults.
+
+## Documentation Contract
+
+- Feature status: harness reliability bug repair.
+- Public docs affected: none; the change aligns behavior with the existing
+  `RunnerConfig` comment.
+- Evidence: engineering and long-term logs, plan, impact map, plans index.
+
+## Test Plan
+
+- Red: retain the exact hosted run-not-found failure as regression evidence.
+- Green: focused pruning test normal/race at `-count=100`.
+- Adjacent/package: all pruning tests and `internal/harness` normal/race.
+- Full: `./scripts/test-regression.sh` and GitHub required checks.
+
+## Cross-Surface Impact Map
+
+- See `2026-07-30-issue-1048-pinned-retention-quota-impact-map.md`.
+
+## Implementation Checklist
+
+- [x] Create contract-complete bug #1048.
+- [x] Capture hosted failure and ownership/search evidence.
+- [x] Write plan and impact map before code.
+- [x] Calculate the cap from drainable terminal candidates.
+- [x] Run focused stress, adjacent, package, and full local gates.
+- [ ] Pass hosted required checks.
+- [ ] Merge through a closing PR.
+
+## Verification
+
+- The focused regression passed normal/race at `-count=100`.
+- All adjacent pruning tests passed normal/race at `-count=20`.
+- The complete `internal/harness` package passed normal and race.
+- The isolated coverage phase and a subsequent complete
+  `./scripts/test-regression.sh` passed with 85.6% coverage and zero uncovered
+  functions.
+
+## Risks and Mitigations
+
+- Risk: pinned runs can temporarily exceed the numeric cap.
+- Mitigation: this is the documented exception; cancellation re-runs pruning.
+- Risk: the change could retain too many unpinned runs.
+- Mitigation: assert the zero-subscriber candidate set stays at or below the
+  configured limit after every pruning trigger.
diff --git a/docs/plans/INDEX.md b/docs/plans/INDEX.md
index 1ad32473..948eea48 100644
--- a/docs/plans/INDEX.md
+++ b/docs/plans/INDEX.md
@@ -12,6 +12,8 @@
 - `2026-07-30-issue-1039-worktree-containment-ci-impact-map.md` — Cross-surface impact map for Issue #1039.
 - `2026-07-30-issue-1042-default-registry-repeat-plan.md` — Issue #1042 planned repeatable top-level workspace registry contract test.
 - `2026-07-30-issue-1042-default-registry-repeat-impact-map.md` — Cross-surface impact map for Issue #1042.
+- `2026-07-30-issue-1048-pinned-retention-quota-plan.md` — Issue #1048 planned exclusion of subscriber-pinned runs from the drainable terminal retention quota.
+- `2026-07-30-issue-1048-pinned-retention-quota-impact-map.md` — Cross-surface impact map for Issue #1048.
 - `2026-07-30-issue-1035-workflow-subscription-cancel-plan.md` — Issue #1035 planned deterministic workflow subscription-cancellation regression repair.
 - `2026-07-30-issue-1035-workflow-subscription-cancel-impact-map.md` — Cross-surface impact map for Issue #1035.
 - `2026-07-30-issue-1026-feedback-direct-publish-plan.md` — Issue #1026 attached-image, publish-by-default GitHub feedback intake (implemented and verified; promotion pending).
diff --git a/internal/harness/runner.go b/internal/harness/runner.go
index 2b34cc62..388be4e9 100644
--- a/internal/harness/runner.go
+++ b/internal/harness/runner.go
@@ -528,13 +528,11 @@ func (r *Runner) pruneCompletedRunsLocked() {
 		limit = defaultMaxCompletedRetention
 	}
 
-	terminalCount := 0
 	candidates := make([]retainedRunCandidate, 0)
 	for runID, state := range r.runs {
 		if state == nil || !isTerminalRunStatus(state.run.Status) || !state.terminalEventPersisted {
 			continue
 		}
-		terminalCount++
 		if len(state.subscribers) == 0 {
 			candidates = append(candidates, retainedRunCandidate{
 				id:        runID,
@@ -542,7 +540,10 @@ func (r *Runner) pruneCompletedRunsLocked() {
 			})
 		}
 	}
-	if terminalCount <= limit || len(candidates) == 0 {
+	// Subscriber-pinned terminal runs are protected exceptions until their
+	// subscribers drain; they must not consume the quota for runs that are
+	// actually eligible for pruning.
+	if len(candidates) <= limit {
 		return
 	}
 
@@ -553,10 +554,7 @@ func (r *Runner) pruneCompletedRunsLocked() {
 		return candidates[i].updatedAt.Before(candidates[j].updatedAt)
 	})
 
-	toDelete := terminalCount - limit
-	if toDelete > len(candidates) {
-		toDelete = len(candidates)
-	}
+	toDelete := len(candidates) - limit
 	for i := 0; i < toDelete; i++ {
 		delete(r.runs, candidates[i].id)
 	}
diff --git a/internal/harness/runner_prune_test.go b/internal/harness/runner_prune_test.go
index caeb142f..43291ec6 100644
--- a/internal/harness/runner_prune_test.go
+++ b/internal/harness/runner_prune_test.go
@@ -96,22 +96,37 @@ func TestRunner_PruneKeepsCompletedRunWithActiveSubscriber(t *testing.T) {
 		}
 	}
 
+	extraRunIDs := make([]string, 0, 3)
 	for i := 0; i < 3; i++ {
 		run, err := runner.StartRun(RunRequest{Prompt: fmt.Sprintf("extra %d", i)})
 		if err != nil {
 			t.Fatalf("start extra run %d: %v", i, err)
 		}
+		extraRunIDs = append(extraRunIDs, run.ID)
 		if _, err := collectRunEvents(t, runner, run.ID); err != nil {
 			t.Fatalf("collect extra run %d events: %v", i, err)
 		}
 	}
 
-	runner.mu.RLock()
-	_, ok := runner.runs[pinned.ID]
-	runner.mu.RUnlock()
-	if !ok {
-		t.Fatal("completed run with an active subscriber was pruned")
-	}
+	waitForRunnerPrune(t, runner, func() bool {
+		runner.mu.RLock()
+		defer runner.mu.RUnlock()
+		if len(runner.runs) != 2 {
+			return false
+		}
+		if _, ok := runner.runs[pinned.ID]; !ok {
+			return false
+		}
+		if _, ok := runner.runs[extraRunIDs[len(extraRunIDs)-1]]; !ok {
+			return false
+		}
+		for _, runID := range extraRunIDs[:len(extraRunIDs)-1] {
+			if _, ok := runner.runs[runID]; ok {
+				return false
+			}
+		}
+		return true
+	})
 
 	cancelPinned()