From 7e9d00b80b76fe39786f7f00d8a6d584d3ea32b0 Mon Sep 17 00:00:00 2001
From: Felix Martin <mail@felixm.de>
Date: Sun, 31 May 2026 16:42:48 -0400
Subject: [PATCH] Port allowed-context matching to evidence package

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
---
 internal/evidence/context.go      | 96 +++++++++++++++++++++++++++++++
 internal/evidence/context_test.go | 75 ++++++++++++++++++++++++
 2 files changed, 171 insertions(+)
 create mode 100644 internal/evidence/context.go
 create mode 100644 internal/evidence/context_test.go

diff --git a/internal/evidence/context.go b/internal/evidence/context.go
new file mode 100644
index 0000000..c9877d2
--- /dev/null
+++ b/internal/evidence/context.go
@@ -0,0 +1,96 @@
+package evidence
+
+import (
+	"strings"
+
+	"antidrift/internal/domain"
+)
+
+// MatchesAllowed reports whether a window (class/title) is on-task per ctx.
+// M3 matches on window class and title only; the domain and command helpers are
+// ported for completeness and tests but have no live data source yet.
+func MatchesAllowed(ctx domain.AllowedContext, class, title string) bool {
+	return windowClassAllowed(ctx, class) || windowTitleAllowed(ctx, title)
+}
+
+func windowClassAllowed(ctx domain.AllowedContext, candidate string) bool {
+	candidate = normalizeCasefolded(candidate)
+	if candidate == "" {
+		return false
+	}
+	for _, allowed := range ctx.WindowClasses {
+		if normalizeCasefolded(allowed) == candidate {
+			return true
+		}
+	}
+	return false
+}
+
+func windowTitleAllowed(ctx domain.AllowedContext, candidate string) bool {
+	candidate = normalizeCasefolded(candidate)
+	if candidate == "" {
+		return false
+	}
+	for _, allowed := range ctx.WindowTitleSubstrings {
+		a := normalizeCasefolded(allowed)
+		if a != "" && strings.Contains(candidate, a) {
+			return true
+		}
+	}
+	return false
+}
+
+func domainAllowed(ctx domain.AllowedContext, candidate string) bool {
+	candidate = normalizeDomain(candidate)
+	if candidate == "" {
+		return false
+	}
+	for _, allowed := range ctx.Domains {
+		a := normalizeDomain(allowed)
+		if a == "" {
+			continue
+		}
+		if candidate == a {
+			return true
+		}
+		if strings.HasSuffix(candidate, a) && strings.HasSuffix(candidate[:len(candidate)-len(a)], ".") {
+			return true
+		}
+	}
+	return false
+}
+
+func commandAllowed(ctx domain.AllowedContext, candidate string) bool {
+	candidate = executableBasename(candidate)
+	if candidate == "" {
+		return false
+	}
+	for _, allowed := range ctx.Commands {
+		if executableBasename(allowed) == candidate {
+			return true
+		}
+	}
+	return false
+}
+
+func normalizeDomain(v string) string {
+	return strings.ToLower(strings.TrimRight(strings.TrimSpace(v), "."))
+}
+
+func normalizeCasefolded(v string) string {
+	return strings.ToLower(strings.TrimSpace(v))
+}
+
+// executableBasename returns the lowercased basename of the first whitespace-
+// separated token (the executable), splitting on both / and \.
+func executableBasename(command string) string {
+	fields := strings.Fields(command)
+	if len(fields) == 0 {
+		return ""
+	}
+	exe := fields[0]
+	if i := strings.LastIndexAny(exe, `/\`); i >= 0 {
+		exe = exe[i+1:]
+	}
+	return strings.ToLower(strings.TrimSpace(exe))
+}
diff --git a/internal/evidence/context_test.go b/internal/evidence/context_test.go
new file mode 100644
index 0000000..de307b9
--- /dev/null
+++ b/internal/evidence/context_test.go
@@ -0,0 +1,75 @@
+package evidence
+
+import (
+	"testing"
+
+	"antidrift/internal/domain"
+)
+
+func TestWindowClassMatchesCaseAndTrim(t *testing.T) {
+	ctx := domain.AllowedContext{WindowClasses: []string{" code "}}
+	if !windowClassAllowed(ctx, " Code ") {
+		t.Fatal("class should match case-insensitively after trim")
+	}
+	if windowClassAllowed(ctx, "firefox") {
+		t.Fatal("unrelated class must not match")
+	}
+	if windowClassAllowed(ctx, "  ") {
+		t.Fatal("empty candidate must not match")
+	}
+}
+
+func TestWindowTitleMatchesSubstring(t *testing.T) {
+	ctx := domain.AllowedContext{WindowTitleSubstrings: []string{" antidrift "}}
+	if !windowTitleAllowed(ctx, "Commitment OS - AntiDrift") {
+		t.Fatal("title substring should match after trim/casefold")
+	}
+	if windowTitleAllowed(ctx, "random video") {
+		t.Fatal("unrelated title must not match")
+	}
+}
+
+func TestDomainMatchesExactAndSubdomain(t *testing.T) {
+	ctx := domain.AllowedContext{Domains: []string{" GitHub.COM. "}}
+	if !domainAllowed(ctx, "github.com") {
+		t.Fatal("exact domain should match")
+	}
+	if !domainAllowed(ctx, " DOCS.GITHUB.COM. ") {
+		t.Fatal("subdomain should match after normalization")
+	}
+	if domainAllowed(ctx, "evilgithub.com") {
+		t.Fatal("suffix-without-dot must not match")
+	}
+}
+
+func TestCommandMatchesExecutableBasename(t *testing.T) {
+	ctx := domain.AllowedContext{Commands: []string{"cargo"}}
+	if !commandAllowed(ctx, "/home/felixm/.cargo/bin/cargo test") {
+		t.Fatal("basename of full path should match")
+	}
+	if !commandAllowed(ctx, "cargo") {
+		t.Fatal("bare command should match")
+	}
+	if commandAllowed(ctx, "/usr/bin/git status") {
+		t.Fatal("unrelated command must not match")
+	}
+}
+
+func TestMatchesAllowedClassOrTitle(t *testing.T) {
+	ctx := domain.AllowedContext{
+		WindowClasses:         []string{"code"},
+		WindowTitleSubstrings: []string{"antidrift"},
+	}
+	if !MatchesAllowed(ctx, "Code", "anything") {
+		t.Fatal("class match should satisfy MatchesAllowed")
+	}
+	if !MatchesAllowed(ctx, "firefox", "my AntiDrift tab") {
+		t.Fatal("title match should satisfy MatchesAllowed")
+	}
+	if MatchesAllowed(ctx, "firefox", "youtube") {
+		t.Fatal("neither match must be off-task")
+	}
+	if MatchesAllowed(domain.AllowedContext{}, "code", "antidrift") {
+		t.Fatal("empty context matches nothing")
+	}
+}