feat(trace): e2e adapter for Pi

app/cli/internal/trace/e2e/checks_more.go

@@ -143,8 +143,14 @@ func checkGenericSessionStored(s *Session) error {
 // checkNoSessionStartHook makes sure that the session-start hook did not
 // fire, so that the scenario tests a missed session start.
 func checkNoSessionStartHook(s *Session) error {
-	if _, err := hookMessage(s, "SessionStart"); err == nil {
+	_, err := hookMessage(s, "SessionStart")
+	switch {
+	case err == nil:
 		return errors.New("the session-start hook fired, so the scenario does not test a missed start")
+	case errors.Is(err, errNotCovered):
+		// A harness that reports no hook messages cannot show that the hook
+		// did not fire.
+		return err
 	}
 	return nil
 }

app/cli/internal/trace/e2e/claude.go

@@ -74,7 +74,7 @@ func (c *Claude) Version(ctx context.Context) (string, error) {
 func (c *Claude) Run(ctx context.Context, req RunRequest) (*RunOutput, error) {
 	args := []string{
 		"-p", req.Prompt,
-		"--model", req.Model,
+		flagModel, req.Model,
 		"--output-format", "stream-json",
 		"--verbose",
 		"--include-hook-events",
@@ -181,7 +181,7 @@ func (c *Claude) HookConfig() HookConfig {
   }
 }
 `,
-		UserMarker: "e2e-user-hook",
+		UserMarker: userHookMarker,
 	}
 }
 

app/cli/internal/trace/e2e/config.yaml

@@ -14,6 +14,10 @@ harnesses:
     version: "2.0.22"
     models:
       - openrouter/anthropic/claude-haiku-5.5
+  Pi:
+    version: "1.3.0"
+    models:
+      - openrouter/anthropic/claude-haiku-5.5
 
 # Runs and pass threshold of a cell whose feature depends on the model
 # following an instruction (R-006, D-004). A cell of any other feature runs

app/cli/internal/trace/e2e/e2e_test.go

@@ -130,6 +130,7 @@ func TestTraceMatrix(t *testing.T) {
 var harnesses = map[string]Harness{
 	HarnessClaudeCode: &Claude{},
 	"OpenCode 2":      &OpenCode{Major: "2"},
+	"Pi":              &Pi{},
 }
 
 // configuredHarnesses returns the adapters of the harnesses that the suite

app/cli/internal/trace/e2e/harness.go

@@ -20,6 +20,13 @@ import "context"
 // HarnessClaudeCode is the column name of Claude Code in the feature table.
 const HarnessClaudeCode = "Claude Code"
 
+const (
+	// flagModel is the model flag that all the harnesses share.
+	flagModel = "--model"
+	// userHookMarker is in the hook of the user that a scenario seeds.
+	userHookMarker = "e2e-user-hook"
+)
+
 // RunRequest is one headless session of a harness.
 type RunRequest struct {
 	// Dir is the repository the session runs in.

app/cli/internal/trace/e2e/opencode.go

@@ -94,7 +94,7 @@ func (o *OpenCode) Version(ctx context.Context) (string, error) {
 // as synthetic messages, which the run output does not show. Run exports the
 // session after the run and reads them from the export.
 func (o *OpenCode) Run(ctx context.Context, req RunRequest) (*RunOutput, error) {
-	args := []string{"run", "--standalone", "--format", "json", "--auto", "--model", req.Model}
+	args := []string{"run", "--standalone", "--format", "json", "--auto", flagModel, req.Model}
 
 	// A pasted image goes in as an attached file, from outside the
 	// repository, so that the agent cannot commit it.
@@ -274,7 +274,7 @@ export default {
   async setup() {},
 }
 `,
-		UserMarker: "e2e-user-hook",
+		UserMarker: userHookMarker,
 	}
 }
 

app/cli/internal/trace/e2e/pi.go

@@ -0,0 +1,157 @@
+//
+// Copyright 2026 The Chainloop Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package e2e
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"regexp"
+	"slices"
+	"strings"
+)
+
+// piExtensionPath is the extension file where `trace init` installs the Pi
+// hooks (spec issue-3520, D-002).
+const piExtensionPath = ".pi/extensions/chainloop-trace.ts"
+
+var piVersionRe = regexp.MustCompile(`\d+\.\d+\.\d+`)
+
+// Pi is the harness adapter of the Pi coding agent.
+type Pi struct {
+	// Bin is the pi executable. Empty means "pi" from PATH.
+	Bin string
+}
+
+func (p *Pi) bin() string {
+	if p.Bin != "" {
+		return p.Bin
+	}
+	return "pi"
+}
+
+// Column implements Harness.
+func (p *Pi) Column() string { return "Pi" }
+
+// TraceFlag implements Harness.
+func (p *Pi) TraceFlag() string { return "--pi" }
+
+// Version implements Harness. `pi --version` prints "0.79.6".
+func (p *Pi) Version(ctx context.Context) (string, error) {
+	out, err := exec.CommandContext(ctx, p.bin(), "--version").Output() //nolint:gosec // the harness binary under test // nosemgrep
+	if err != nil {
+		return "", fmt.Errorf("pi --version: %w", err)
+	}
+	v := piVersionRe.FindString(string(out))
+	if v == "" {
+		return "", fmt.Errorf("pi --version: no version in %q", strings.TrimSpace(string(out)))
+	}
+	return v, nil
+}
+
+// Run implements Harness. It runs `pi -p` with the JSON output.
+//
+// The configuration folder of Pi and its session folder are next to the
+// workspace, so the extensions, the skills and the settings of the user who
+// runs the suite do not load, and the sessions of the suite do not mix with
+// the sessions of the user. --approve trusts the project files of the
+// workspace, which hold the Chainloop extension.
+//
+// The Chainloop extension gives its instruction and reminder to the model as
+// hidden context, which the run output does not show. Until the suite reads
+// them from the session file, the hook messages are not reported.
+func (p *Pi) Run(ctx context.Context, req RunRequest) (*RunOutput, error) {
+	base := filepath.Dir(req.Dir)
+	args := []string{
+		"-p", "--mode", "json", "--approve",
+		flagModel, req.Model,
+		"--session-dir", filepath.Join(base, "pi-sessions"),
+	}
+
+	// A pasted image goes in as an attached file, from outside the
+	// repository, so that the agent cannot commit it.
+	if len(req.Images) > 0 {
+		dir, err := os.MkdirTemp("", "chainloop-trace-e2e-")
+		if err != nil {
+			return nil, err
+		}
+		defer os.RemoveAll(dir)
+		for i, img := range req.Images {
+			path := filepath.Join(dir, fmt.Sprintf("pasted-%d.png", i+1))
+			if err := os.WriteFile(path, img, 0o600); err != nil {
+				return nil, err
+			}
+			args = append(args, "@"+path)
+		}
+	}
+	args = append(args, req.Prompt)
+
+	name := p.bin()
+	if len(req.Wrapper) > 0 {
+		name = req.Wrapper[0]
+		args = append(append(append([]string{}, req.Wrapper[1:]...), p.bin()), args...)
+	}
+
+	cmd := exec.CommandContext(ctx, name, args...) //nolint:gosec // the harness binary under test, with the prompt of a scenario // nosemgrep
+	cmd.Dir = req.Dir
+	cmd.Env = append(slices.Clone(req.Env),
+		"PI_CODING_AGENT_DIR="+filepath.Join(base, "pi-agent"),
+		"PI_SKIP_VERSION_CHECK=1",
+		"PI_TELEMETRY=0",
+	)
+	var stderr bytes.Buffer
+	cmd.Stderr = &stderr
+
+	raw, err := cmd.Output()
+	if err != nil {
+		return &RunOutput{Raw: raw}, fmt.Errorf("pi -p: %w: %s", err, strings.TrimSpace(stderr.String()))
+	}
+
+	return &RunOutput{Raw: raw}, nil
+}
+
+// HookConfig implements Harness. The Chainloop extension is a file of its
+// own, so the extension of the user is in another file.
+func (p *Pi) HookConfig() HookConfig {
+	return HookConfig{
+		Path:            piExtensionPath,
+		ChainloopMarker: "chainloop",
+		UserPath:        ".pi/extensions/e2e-user.ts",
+		UserConfig: `// e2e-user-hook
+export default function () {}
+`,
+		UserMarker: userHookMarker,
+	}
+}
+
+// errPiSessionStart is the error of DisableSessionStart until the suite
+// knows the shape of the Chainloop extension.
+var errPiSessionStart = errors.New("pi: the suite cannot remove the session-start hook of the Chainloop extension yet")
+
+// DisableSessionStart implements Harness. The Chainloop extension of Pi does
+// not exist yet, so there is no handler to change.
+func (p *Pi) DisableSessionStart(string) error {
+	return errPiSessionStart
+}
+
+// SkillPath implements Harness. Pi finds project skills in .agents/skills.
+func (p *Pi) SkillPath(name string) string {
+	return ".agents/skills/" + name + "/SKILL.md"
+}