Load the knowledge profile on planning and ground the coach

The controller loads the profile asynchronously on entering planning,
mirroring the tasks fetch: generation-guarded goroutine, status enum
(idle/pending/ready/absent/error), projected into State only while
planning and only when a source is set. The loaded text is cached and
passed to the coach as grounding; SetKnowledgePath repoints the file at
runtime. nil source degrades to no view and an ungrounded coach.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

internal/session/session_test.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"path/filepath"
+	"sync"
 	"sync/atomic"
 	"testing"
 	"time"
@@ -12,6 +13,7 @@ import (
 	"antidrift/internal/ai"
 	"antidrift/internal/domain"
 	"antidrift/internal/evidence"
+	"antidrift/internal/knowledge"
 	"antidrift/internal/store"
 	"antidrift/internal/tasks"
 )
@@ -246,15 +248,27 @@ type fakeCoach struct {
 	prop ai.Proposal
 	err  error
 	gate chan struct{} // if non-nil, Coach blocks until it receives
+
+	mu           sync.Mutex
+	gotGrounding string
 }
 
-func (f *fakeCoach) Coach(ctx context.Context, intent string) (ai.Proposal, error) {
+func (f *fakeCoach) Coach(ctx context.Context, intent, grounding string) (ai.Proposal, error) {
+	f.mu.Lock()
+	f.gotGrounding = grounding
+	f.mu.Unlock()
 	if f.gate != nil {
 		<-f.gate
 	}
 	return f.prop, f.err
 }
 
+func (f *fakeCoach) grounding() string {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	return f.gotGrounding
+}
+
 // waitCoachStatus polls until the coach view reaches want, or fails after 2s.
 func waitCoachStatus(t *testing.T, c *Controller, want string) State {
 	t.Helper()
@@ -918,3 +932,100 @@ func TestStaleTasksFetchDiscardedAfterLeavingPlanning(t *testing.T) {
 		t.Fatalf("stale fetch result clobbered the fresh tasks: %+v", st.Tasks)
 	}
 }
+
+type fakeSource struct {
+	profile knowledge.Profile
+	err     error
+}
+
+func (f *fakeSource) Load(ctx context.Context, path string) (knowledge.Profile, error) {
+	return f.profile, f.err
+}
+
+// waitKnowledgeStatus polls until the knowledge view reaches want, or fails after 2s.
+func waitKnowledgeStatus(t *testing.T, c *Controller, want string) State {
+	t.Helper()
+	deadline := time.Now().Add(2 * time.Second)
+	for time.Now().Before(deadline) {
+		st := c.State()
+		if st.Knowledge != nil && st.Knowledge.Status == want {
+			return st
+		}
+		time.Sleep(5 * time.Millisecond)
+	}
+	t.Fatalf("knowledge status never reached %q (last: %+v)", want, c.State().Knowledge)
+	return State{}
+}
+
+func TestEnterPlanningLoadsKnowledge(t *testing.T) {
+	c, _ := newTestController(t)
+	c.SetKnowledge(&fakeSource{profile: knowledge.Profile{Text: "I value small diffs.", Path: "/p/knowledge.md"}})
+	if err := c.EnterPlanning(); err != nil {
+		t.Fatalf("enter planning: %v", err)
+	}
+	st := waitKnowledgeStatus(t, c, "ready")
+	if st.Knowledge.Path != "/p/knowledge.md" || st.Knowledge.Chars != len("I value small diffs.") {
+		t.Fatalf("knowledge view wrong: %+v", st.Knowledge)
+	}
+}
+
+func TestKnowledgeAbsentWhenEmptyText(t *testing.T) {
+	c, _ := newTestController(t)
+	c.SetKnowledge(&fakeSource{profile: knowledge.Profile{Path: "/p/missing.md"}})
+	if err := c.EnterPlanning(); err != nil {
+		t.Fatalf("enter planning: %v", err)
+	}
+	st := waitKnowledgeStatus(t, c, "absent")
+	if st.Knowledge.Path != "/p/missing.md" {
+		t.Fatalf("absent view should still carry the path: %+v", st.Knowledge)
+	}
+}
+
+func TestKnowledgeLoadError(t *testing.T) {
+	c, _ := newTestController(t)
+	c.SetKnowledge(&fakeSource{err: errors.New("permission denied")})
+	if err := c.EnterPlanning(); err != nil {
+		t.Fatalf("enter planning: %v", err)
+	}
+	waitKnowledgeStatus(t, c, "error")
+}
+
+func TestNoSourceNoKnowledgeView(t *testing.T) {
+	c, _ := newTestController(t)
+	if err := c.EnterPlanning(); err != nil {
+		t.Fatalf("enter planning: %v", err)
+	}
+	if c.State().Knowledge != nil {
+		t.Fatalf("nil source should yield no knowledge view: %+v", c.State().Knowledge)
+	}
+}
+
+func TestKnowledgeViewAbsentOutsidePlanning(t *testing.T) {
+	c, _ := newTestController(t)
+	c.SetKnowledge(&fakeSource{profile: knowledge.Profile{Text: "x"}})
+	if c.State().Knowledge != nil {
+		t.Fatalf("no knowledge view while Locked: %+v", c.State().Knowledge)
+	}
+}
+
+func TestCoachReceivesCachedGrounding(t *testing.T) {
+	c, _ := newTestController(t)
+	fc := &fakeCoach{prop: ai.Proposal{NextAction: "a", SuccessCondition: "b", TimeboxSecs: 1200}}
+	c.SetCoach(fc)
+	c.SetKnowledge(&fakeSource{profile: knowledge.Profile{Text: "I value small diffs.", Path: "/p"}})
+	if err := c.EnterPlanning(); err != nil {
+		t.Fatalf("enter planning: %v", err)
+	}
+	waitKnowledgeStatus(t, c, "ready")
+	if err := c.RequestCoach("ship it"); err != nil {
+		t.Fatalf("request coach: %v", err)
+	}
+	// Poll until the coach has run (proposal ready), then assert grounding flowed.
+	deadline := time.Now().Add(2 * time.Second)
+	for time.Now().Before(deadline) && fc.grounding() == "" {
+		time.Sleep(5 * time.Millisecond)
+	}
+	if fc.grounding() != "I value small diffs." {
+		t.Fatalf("coach grounding = %q, want the cached profile", fc.grounding())
+	}
+}