diff --git a/docs/ARCHITECTURE.md b/docs/ARCHITECTURE.md
index 750478f..0d77b3d 100644
--- a/docs/ARCHITECTURE.md
+++ b/docs/ARCHITECTURE.md
@@ -159,9 +159,18 @@ automatic** (D-021).
   is always the key the provider sends. Request and response
   bodies are redacted before they are stored: the decrypted API key,
   Authorization and API-key header values, Google Chat webhook URLs and URLs
-  with key-like query parameters are removed, inside JSON strings too.
+  with key-like query parameters are removed, inside JSON strings too; the
+  skill, provider and model columns are redacted the same way. Writing the
+  row is bounded: a run whose work ended in time must write its row before
+  the skill's deadline or it fails with `llm.ErrTimeout` and its row records
+  the timeout; a failed run's row has a further fixed bound, and if even
+  that write fails the run returns the write error with its own and no row
+  is stored. A stored row's status therefore always matches what the caller
+  received.
   `harness.Purge` deletes rows older than `harness.RunRetention` (30 days),
-  clearing the `suggestion_batches` and `week_plans` references first.
+  clearing the `suggestion_batches` and `week_plans` references first. The
+  harness does not call it: the scheduler's daily `ai_runs` purge
+  (Feature 20) must call `harness.Purge` with `now - RunRetention`.
 - **Concurrency guards** (`harness.Guard`, one per process): `harness.Run`
   takes a scope key, and concurrent runs of one skill with one scope share a
   single in-flight run and its result, error included (single-flight); runs
@@ -221,7 +230,7 @@ purge are fixed and not configurable.
 | `day_of_reminder` | Daily 16:30 | Tonight's dinner reminder. |
 | `rotation_check` | Daily 09:00 | Asks "Keep it in rotation?" for tried dinners. |
 | `week_rollover` | Monday 00:05 (fixed) | Freezes last week's Supply run into the Supply archive. |
-| `ai_runs` purge | Daily (fixed) | Deletes `ai_runs` rows past 30-day retention. |
+| `ai_runs` purge | Daily (fixed) | Calls `harness.Purge` to delete `ai_runs` rows past 30-day retention (Feature 20). |
 
 Runs are recorded in `schedule_runs` and executed through `jobs`.
 
diff --git a/internal/ai/harness/guard_test.go b/internal/ai/harness/guard_test.go
index e292526..04eecd7 100644
--- a/internal/ai/harness/guard_test.go
+++ b/internal/ai/harness/guard_test.go
@@ -300,8 +300,9 @@ func TestRunTimeout(t *testing.T) {
 		cfg := testConfig(t, &f)
 		f.QueueGenerate(reply(`{"echo":"taco"}`))
 		timeout := 100 * time.Millisecond
-		// Holding the store's only writer connection makes the save wait
-		// past the deadline, after the work itself has ended in time.
+		// Holding the store's only writer connection past the deadline
+		// keeps the ok row from being written in time, after the work
+		// itself has ended in time.
 		conn, err := cfg.Store.Writer.Conn(context.Background())
 		if err != nil {
 			t.Fatal(err)
@@ -316,11 +317,39 @@ func TestRunTimeout(t *testing.T) {
 			t.Fatalf("out = %+v, want no output", out)
 		}
 		assertCalls(t, &f, 1)
-		// An ok row with no error proves the work ended in time and only
-		// the save ran past the deadline.
+		// The row records the timeout the caller received, not the ok
+		// outcome the work had.
 		rows := runRows(t, cfg.Store)
-		if len(rows) != 1 || rows[0].Status != string(StatusOK) || rows[0].Error.Valid {
-			t.Fatalf("rows = %+v, want one ok row with no error", rows)
+		if len(rows) != 1 || rows[0].Status != string(StatusProviderError) || !strings.Contains(rows[0].Error.String, llm.ErrTimeout.Error()) {
+			t.Fatalf("rows = %+v, want one provider_error row naming the timeout", rows)
+		}
+	})
+	t.Run("writer blocked", func(t *testing.T) {
+		var f llm.Fake
+		cfg := testConfig(t, &f)
+		f.QueueGenerate(reply(`{"echo":"taco"}`))
+		timeout := 50 * time.Millisecond
+		saveTimeout := runSaveTimeout
+		runSaveTimeout = 100 * time.Millisecond
+		defer func() { runSaveTimeout = saveTimeout }()
+		// The writer stays held until Run has returned, so neither save
+		// can be written.
+		conn, err := cfg.Store.Writer.Conn(context.Background())
+		if err != nil {
+			t.Fatal(err)
+		}
+		started := time.Now()
+		_, err = Run(context.Background(), cfg, timeoutSkill{timeout: timeout}, "week-1", echoInput{Word: "taco"})
+		elapsed := time.Since(started)
+		conn.Close()
+		if !errors.Is(err, llm.ErrTimeout) || !strings.Contains(err.Error(), "record ai_runs row") {
+			t.Fatalf("err = %v, want ErrTimeout and the row write failure", err)
+		}
+		if bound := timeout + runSaveTimeout + time.Second; elapsed > bound {
+			t.Fatalf("Run took %v with the writer blocked, want at most %v", elapsed, bound)
+		}
+		if rows := runRows(t, cfg.Store); len(rows) != 0 {
+			t.Fatalf("rows = %+v, want none", rows)
 		}
 	})
 	t.Run("waiting for a slot", func(t *testing.T) {
diff --git a/internal/ai/harness/harness.go b/internal/ai/harness/harness.go
index 0ec9ee3..c1d7296 100644
--- a/internal/ai/harness/harness.go
+++ b/internal/ai/harness/harness.go
@@ -42,8 +42,8 @@ type Skill[In, Out any] interface {
 	// is validated again; problems found then are repaired like any other.
 	// Its error fails the run without a repair turn.
 	PostProcess(out Out) (Out, error)
-	// Timeout bounds a whole run, waiting for LLM call slots and the
-	// repair turn included. It is DefaultTimeout unless the skill needs
+	// Timeout bounds a whole run, waiting for LLM call slots, the repair
+	// turn and writing a successful run's ai_runs row included (see Run). It is DefaultTimeout unless the skill needs
 	// another, and must be positive.
 	Timeout() time.Duration
 }
@@ -136,6 +136,15 @@ func (e *BadOutputError) Unwrap() error { return llm.ErrBadOutput }
 // before anything else, and writes no row since the row cannot be
 // written without one. When the row cannot be written the run fails with
 // that error too, even if its output was usable.
+//
+// Writing the row is bounded too. A run whose work ended in time must
+// write its row before s.Timeout() as well; if the store's writer is not
+// free by then, the run fails with llm.ErrTimeout and its row records the
+// timeout instead. The row of a run that failed is written within a
+// further fixed bound (runSaveTimeout); if it cannot be, the run fails with
+// the write error alongside its own, and no row is stored. So Run returns
+// at most that bound after s.Timeout(), and a stored row's status always
+// matches what the caller received.
 func Run[In, Out any](ctx context.Context, cfg Config, s Skill[In, Out], scope string, in In) (Out, error) {
 	var zero Out
 	if err := cfg.validate(); err != nil {
@@ -168,7 +177,7 @@ func runOnce[In, Out any](ctx context.Context, cfg Config, s Skill[In, Out], tim
 	deadline := time.Now().Add(timeout)
 	ctx, cancel := context.WithDeadlineCause(ctx, deadline, expired)
 	defer cancel()
-	log := &runLog{start: store.Now()}
+	log := &runLog{id: store.NewID(), start: store.Now()}
 	out, status, err := execute(ctx, cfg, s, in, log)
 	// Work that only ends after the deadline, such as a slow PostProcess,
 	// may return no error; it is still a timeout, not a success. The clock
@@ -180,19 +189,34 @@ func runOnce[In, Out any](ctx context.Context, cfg Config, s Skill[In, Out], tim
 			err = fmt.Errorf("%w: %w", expired, err)
 		}
 	}
-	if saveErr := log.save(ctx, cfg, s.Name(), s.Version(), status, err); saveErr != nil {
+	// The saves ignore the callers' cancellation, so a cancelled run is
+	// recorded too, but each is bounded. Work that ended in time must also
+	// be recorded in time: its row is written within the deadline or not at
+	// all, so a stored ok or repaired row always means the caller got the
+	// output.
+	if err == nil {
+		sctx, cancel := context.WithDeadline(context.WithoutCancel(ctx), deadline)
+		saveErr := log.save(sctx, cfg, s.Name(), s.Version(), status, nil)
+		late := sctx.Err() != nil
+		cancel()
+		if saveErr == nil {
+			return out, nil
+		}
+		if !late {
+			return zero, fmt.Errorf("harness: skill %s v%d: record ai_runs row: %w", s.Name(), s.Version(), saveErr)
+		}
+		// The store's writer was not free before the deadline, so the run
+		// has not ended in time.
+		err, status = expired, StatusProviderError
+	}
+	// A run that failed is recorded within runSaveTimeout; when it cannot
+	// be, the run fails with both errors.
+	sctx, cancel := context.WithTimeout(context.WithoutCancel(ctx), runSaveTimeout)
+	defer cancel()
+	if saveErr := log.save(sctx, cfg, s.Name(), s.Version(), status, err); saveErr != nil {
 		return zero, errors.Join(err, fmt.Errorf("harness: skill %s v%d: record ai_runs row: %w", s.Name(), s.Version(), saveErr))
 	}
-	if err != nil {
-		return zero, err
-	}
-	// The save may wait past the deadline for the store's single writer.
-	// The run has then not ended in time, so it fails, though its row
-	// records the work's outcome as it stood before the save.
-	if !time.Now().Before(deadline) {
-		return zero, expired
-	}
-	return out, nil
+	return zero, err
 }
 
 // execute renders the prompt, builds the provider and sends the turns,
diff --git a/internal/ai/harness/runs.go b/internal/ai/harness/runs.go
index fb12141..5bf2e86 100644
--- a/internal/ai/harness/runs.go
+++ b/internal/ai/harness/runs.go
@@ -38,9 +38,17 @@ const (
 // Purge with time.Now().Add(-RunRetention).
 const RunRetention = 30 * 24 * time.Hour
 
+// runSaveTimeout bounds writing the ai_runs row of a run that has failed,
+// timed out or been cancelled, so a blocked writer cannot hold Run up
+// indefinitely. A variable so tests can shorten it.
+var runSaveTimeout = 5 * time.Second
+
 // Purge deletes the ai_runs rows created before olderThan and returns how
 // many it deleted. The suggestion_batches and week_plans references to
 // those rows are cleared first, in the same transaction.
+//
+// Nothing in this package calls Purge: the scheduler's daily ai_runs purge
+// (Feature 20) must call it with time.Now().Add(-RunRetention).
 func Purge(ctx context.Context, st *store.Store, olderThan time.Time) (int64, error) {
 	if olderThan.IsZero() {
 		return 0, errors.New("harness: purge ai_runs: zero cutoff")
@@ -67,6 +75,9 @@ func Purge(ctx context.Context, st *store.Store, olderThan time.Time) (int64, er
 
 // runLog collects one run's turns for its ai_runs row.
 type runLog struct {
+	// id is the row's ID, fixed for the run so that a second save attempt
+	// can never add a second row.
+	id        string
 	start     store.Timestamp
 	requests  []loggedRequest
 	responses []loggedResponse
@@ -138,8 +149,8 @@ func (l *runLog) add(apiKey string, req llm.Request, resp llm.Response, err erro
 	l.tokensOut += int64(resp.Usage.OutputTokens)
 }
 
-// save writes the run's ai_runs row. It is written even when ctx is done,
-// so a cancelled run is recorded too.
+// save writes the run's ai_runs row within ctx, which the caller bounds.
+// Every stored string is redacted.
 func (l *runLog) save(ctx context.Context, cfg Config, skill string, version int, status RunStatus, runErr error) error {
 	// A run that failed before its first turn stores an empty list.
 	request, err := marshalRedacted(nonNil(l.requests), cfg.APIKey)
@@ -158,12 +169,12 @@ func (l *runLog) save(ctx context.Context, cfg Config, skill string, version int
 		errText = sql.NullString{String: redact("first reply: "+strings.Join(l.problems, "; "), cfg.APIKey), Valid: true}
 	}
 	now := store.Now()
-	return db.New(cfg.Store.Writer).CreateAIRun(context.WithoutCancel(ctx), db.CreateAIRunParams{
-		ID:               store.NewID(),
-		Skill:            skill,
+	return db.New(cfg.Store.Writer).CreateAIRun(ctx, db.CreateAIRunParams{
+		ID:               l.id,
+		Skill:            redact(skill, cfg.APIKey),
 		SkillVersion:     strconv.Itoa(version),
-		Provider:         cfg.Settings.Provider,
-		Model:            cfg.Settings.Model,
+		Provider:         redact(cfg.Settings.Provider, cfg.APIKey),
+		Model:            redact(cfg.Settings.Model, cfg.APIKey),
 		Temperature:      cfg.Settings.Temperature,
 		Status:           string(status),
 		LatencyMs:        sql.NullInt64{Int64: now.Sub(l.start.Time).Milliseconds(), Valid: true},
diff --git a/internal/ai/harness/runs_test.go b/internal/ai/harness/runs_test.go
index 963207a..64d7107 100644
--- a/internal/ai/harness/runs_test.go
+++ b/internal/ai/harness/runs_test.go
@@ -276,6 +276,9 @@ func TestRunRowsHoldNoSecrets(t *testing.T) {
 				return &f, nil
 			}
 			cfg.Persona = "Our kitchen. " + leaky
+			// A model value can hold a credential too: every stored
+			// column is redacted, not only the bodies.
+			cfg.Settings.Model = "model-" + seededKey + " " + seededWebhook
 			_, _ = Run(context.Background(), cfg, echoSkill{}, "week-1", echoInput{Word: "tacos " + seededWebhook})
 			assertCalls(t, &f, len(script))
 
@@ -289,6 +292,9 @@ func TestRunRowsHoldNoSecrets(t *testing.T) {
 					t.Errorf("stored row holds %q:\n%s", s, text)
 				}
 			}
+			if want := "model-" + redactionMarker + " " + redactionMarker; rows[0].Model != want {
+				t.Errorf("stored model = %q, want %q", rows[0].Model, want)
+			}
 			for _, kept := range []string{"Our kitchen.", "Repeat: tacos", redactionMarker} {
 				if !strings.Contains(text, kept) {
 					t.Errorf("stored row lacks %q:\n%s", kept, text)