Add reverse Slack->GitHub mapping for a better home experience

cmd/server/main.go

@@ -23,6 +23,7 @@ import (
 	"github.com/codeGROOVE-dev/slacker/pkg/notify"
 	"github.com/codeGROOVE-dev/slacker/pkg/slack"
 	"github.com/codeGROOVE-dev/slacker/pkg/state"
+	"github.com/codeGROOVE-dev/slacker/pkg/usermapping"
 	"github.com/codeGROOVE-dev/sprinkler/pkg/client"
 	"github.com/gorilla/mux"
 	"golang.org/x/sync/errgroup"
@@ -244,8 +245,24 @@ func run(ctx context.Context, cancel context.CancelFunc, cfg *config.ServerConfi
 	// Initialize event router for multi-workspace event handling.
 	eventRouter := slack.NewEventRouter(slackManager)
 
+	// Initialize reverse user mapping service (Slack → GitHub)
+	// Get GitHub token from one of the installations
+	var githubToken string
+	for _, org := range githubManager.AllOrgs() {
+		if client, ok := githubManager.ClientForOrg(org); ok {
+			githubToken = client.InstallationToken(ctx)
+			break
+		}
+	}
+	if githubToken == "" {
+		slog.Warn("no GitHub installations found - reverse user mapping will not work")
+	}
+	// Pass nil for Slack client - it will be provided per-request in HomeHandler
+	reverseMapping := usermapping.NewReverseService(nil, githubToken)
+	slog.Info("initialized reverse user mapping service (Slack → GitHub)")
+
 	// Initialize home view handler
-	homeHandler := slack.NewHomeHandler(slackManager, githubManager, configManager, stateStore)
+	homeHandler := slack.NewHomeHandler(slackManager, githubManager, configManager, stateStore, reverseMapping)
 	slackManager.SetHomeViewHandler(homeHandler.HandleAppHomeOpened)
 
 	// Initialize OAuth handler for Slack app installation.

go.mod

@@ -4,7 +4,7 @@ go 1.25.1
 
 require (
 	github.com/codeGROOVE-dev/ds9 v0.6.0
-	github.com/codeGROOVE-dev/gh-mailto v0.0.0-20251024133418-149270eb16a9
+	github.com/codeGROOVE-dev/gh-mailto v0.0.0-20251030132316-7b86852c2928
 	github.com/codeGROOVE-dev/gsm v0.0.0-20251019065141-833fe2363d22
 	github.com/codeGROOVE-dev/prx v0.0.0-20251030022101-ff906928a1e4
 	github.com/codeGROOVE-dev/retry v1.3.0

go.sum

@@ -4,8 +4,8 @@ github.com/cloudflare/circl v1.6.1 h1:zqIqSPIndyBh1bjLVVDHMPpVKqp8Su/V+6MeDzzQBQ
 github.com/cloudflare/circl v1.6.1/go.mod h1:uddAzsPgqdMAYatqJ0lsjX1oECcQLIlRpzZh3pJrofs=
 github.com/codeGROOVE-dev/ds9 v0.6.0 h1:JG7vBH17UAKaVoeQilrIvA1I0fg3iNbdUMBSDS7ixgI=
 github.com/codeGROOVE-dev/ds9 v0.6.0/go.mod h1:0UDipxF1DADfqM5GtjefgB2u+EXdDgOKmxVvrSGLHoM=
-github.com/codeGROOVE-dev/gh-mailto v0.0.0-20251024133418-149270eb16a9 h1:eyWcEZd3xyLV2WxShoyKWakFyxQGvOSv89ponU3Ah0I=
-github.com/codeGROOVE-dev/gh-mailto v0.0.0-20251024133418-149270eb16a9/go.mod h1:4Hr2ySB8dcpeZqZq/7UbXdEJ/5RK9coYGHvW90ZfieE=
+github.com/codeGROOVE-dev/gh-mailto v0.0.0-20251030132316-7b86852c2928 h1:fDiQ7GnN6tDUIrYqXKCmxcatFzZqr+Bp3aNBA0Q2AVk=
+github.com/codeGROOVE-dev/gh-mailto v0.0.0-20251030132316-7b86852c2928/go.mod h1:4Hr2ySB8dcpeZqZq/7UbXdEJ/5RK9coYGHvW90ZfieE=
 github.com/codeGROOVE-dev/gsm v0.0.0-20251019065141-833fe2363d22 h1:gtN3rOc6YspO646BkcOxBhPjEqKUz+jl175jIqglfDg=
 github.com/codeGROOVE-dev/gsm v0.0.0-20251019065141-833fe2363d22/go.mod h1:KV+w19ubP32PxZPE1hOtlCpTaNpF0Bpb32w5djO8UTg=
 github.com/codeGROOVE-dev/prx v0.0.0-20251030022101-ff906928a1e4 h1:DSuoUwP3oyR4cHrX0cUh9c7CtYjXNIcyCmqpIwHilIU=

pkg/config/config.go

@@ -51,6 +51,7 @@ type RepoConfig struct {
 		ReminderDMDelay int    `yaml:"reminder_dm_delay"` // Minutes to wait before sending DM if user tagged in channel (0 = disabled)
 		DailyReminders  bool   `yaml:"daily_reminders"`
 	} `yaml:"global"`
+	Users map[string]string `yaml:"users"` // GitHub username -> email address (for manual overrides)
 }
 
 // configCacheEntry represents a cached configuration entry.

pkg/home/ui.go

@@ -6,6 +6,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/codeGROOVE-dev/slacker/pkg/usermapping"
 	"github.com/slack-go/slack"
 )
 
@@ -226,3 +227,61 @@ func formatEnhancedPRBlock(pr *PR) slack.Block {
 		nil,
 	)
 }
+
+// BuildBlocksWithDebug creates Slack Block Kit UI with debug information about user mapping.
+func BuildBlocksWithDebug(dashboard *Dashboard, primaryOrg string, mapping *usermapping.ReverseMapping) []slack.Block {
+	// Build standard blocks first
+	blocks := BuildBlocks(dashboard, primaryOrg)
+
+	// Add debug section if mapping info is available
+	if mapping != nil {
+		blocks = append(blocks,
+			slack.NewDividerBlock(),
+			slack.NewSectionBlock(
+				slack.NewTextBlockObject("mrkdwn",
+					fmt.Sprintf("🔍 *Debug Info*\n"+
+						"GitHub: `@%s`  •  Mapped via: `%s`  •  Confidence: `%d%%`",
+						mapping.GitHubUsername,
+						mapping.MatchMethod,
+						mapping.Confidence),
+					false,
+					false,
+				),
+				nil,
+				nil,
+			),
+		)
+
+		// Add mapping guidance if confidence is low
+		if mapping.Confidence < 80 {
+			blocks = append(blocks,
+				slack.NewContextBlock("",
+					slack.NewTextBlockObject("mrkdwn",
+						fmt.Sprintf("⚠️  Low confidence mapping. Add manual override to `slack.yaml`:\n```yaml\nusers:\n  %s: %s\n```",
+							mapping.GitHubUsername,
+							mapping.SlackEmail),
+						false,
+						false,
+					),
+				),
+			)
+		}
+	} else {
+		// No mapping found - show error message
+		blocks = append(blocks,
+			slack.NewDividerBlock(),
+			slack.NewSectionBlock(
+				slack.NewTextBlockObject("mrkdwn",
+					"❌ *Could not map Slack user to GitHub*\n"+
+						"Add your mapping to `.codeGROOVE/slack.yaml`:\n```yaml\nusers:\n  your-github-username: [email protected]\n```",
+					false,
+					false,
+				),
+				nil,
+				nil,
+			),
+		)
+	}
+
+	return blocks
+}

pkg/slack/home_handler.go

@@ -11,15 +11,17 @@ import (
 	"github.com/codeGROOVE-dev/slacker/pkg/github"
 	"github.com/codeGROOVE-dev/slacker/pkg/home"
 	"github.com/codeGROOVE-dev/slacker/pkg/state"
+	"github.com/codeGROOVE-dev/slacker/pkg/usermapping"
 	gogithub "github.com/google/go-github/v50/github"
 )
 
 // HomeHandler handles app_home_opened events for a workspace.
 type HomeHandler struct {
-	slackManager  *Manager
-	githubManager *github.Manager
-	configManager *config.Manager
-	stateStore    state.Store
+	slackManager   *Manager
+	githubManager  *github.Manager
+	configManager  *config.Manager
+	stateStore     state.Store
+	reverseMapping *usermapping.ReverseService
 }
 
 // NewHomeHandler creates a new home view handler.
@@ -28,12 +30,14 @@ func NewHomeHandler(
 	githubManager *github.Manager,
 	configManager *config.Manager,
 	stateStore state.Store,
+	reverseMapping *usermapping.ReverseService,
 ) *HomeHandler {
 	return &HomeHandler{
-		slackManager:  slackManager,
-		githubManager: githubManager,
-		configManager: configManager,
-		stateStore:    stateStore,
+		slackManager:   slackManager,
+		githubManager:  githubManager,
+		configManager:  configManager,
+		stateStore:     stateStore,
+		reverseMapping: reverseMapping,
 	}
 }
 
@@ -77,36 +81,35 @@ func (h *HomeHandler) tryHandleAppHomeOpened(ctx context.Context, teamID, slackU
 		return fmt.Errorf("failed to get Slack client: %w", err)
 	}
 
-	// Get Slack user info to extract email
-	slackUser, err := slackClient.API().GetUserInfo(slackUserID)
-	if err != nil {
-		// Don't mask invalid_auth errors - let them propagate for retry logic
-		if strings.Contains(err.Error(), "invalid_auth") {
-			return fmt.Errorf("failed to get Slack user info: %w", err)
-		}
-		slog.Warn("failed to get Slack user info", "user_id", slackUserID, "error", err)
-		return h.publishPlaceholderHome(ctx, slackClient, slackUserID)
-	}
-
-	// Extract GitHub username from email (simple heuristic: part before @)
-	// Works for "[email protected]" -> "username"
-	email := slackUser.Profile.Email
-	atIndex := strings.IndexByte(email, '@')
-	if atIndex <= 0 {
-		slog.Warn("could not extract GitHub username from Slack email",
-			"slack_user_id", slackUserID,
-			"email", email)
-		return h.publishPlaceholderHome(ctx, slackClient, slackUserID)
-	}
-	githubUsername := email[:atIndex]
-
 	// Get all orgs for this workspace
 	workspaceOrgs := h.workspaceOrgs(teamID)
 	if len(workspaceOrgs) == 0 {
 		slog.Warn("no workspace orgs found", "team_id", teamID)
-		return h.publishPlaceholderHome(ctx, slackClient, slackUserID)
+		return h.publishPlaceholderHome(ctx, slackClient, slackUserID, nil)
+	}
+
+	// Get config for first org to extract domain and user overrides
+	cfg, exists := h.configManager.Config(workspaceOrgs[0])
+	if !exists {
+		return fmt.Errorf("no config for org: %s", workspaceOrgs[0])
 	}
 
+	// Update reverse mapping overrides from config
+	if len(cfg.Users) > 0 {
+		h.reverseMapping.SetOverrides(cfg.Users)
+	}
+
+	// Map Slack user to GitHub username
+	mapping, err := h.reverseMapping.LookupGitHub(ctx, slackClient.API(), slackUserID, workspaceOrgs[0], cfg.Global.EmailDomain)
+	if err != nil {
+		slog.Warn("failed to map Slack user to GitHub",
+			"slack_user_id", slackUserID,
+			"error", err)
+		return h.publishPlaceholderHome(ctx, slackClient, slackUserID, nil)
+	}
+
+	githubUsername := mapping.GitHubUsername
+
 	// Get GitHub client for first org (they all share the same app)
 	githubClient, ok := h.githubManager.ClientForOrg(workspaceOrgs[0])
 	if !ok {
@@ -130,14 +133,14 @@ func (h *HomeHandler) tryHandleAppHomeOpened(ctx context.Context, teamID, slackU
 		slog.Error("failed to fetch dashboard",
 			"github_user", githubUsername,
 			"error", err)
-		return h.publishPlaceholderHome(ctx, slackClient, slackUserID)
+		return h.publishPlaceholderHome(ctx, slackClient, slackUserID, mapping)
 	}
 
 	// Add workspace orgs to dashboard for UI display
 	dashboard.WorkspaceOrgs = workspaceOrgs
 
-	// Build Block Kit UI - use first org as primary
-	blocks := home.BuildBlocks(dashboard, workspaceOrgs[0])
+	// Build Block Kit UI - use first org as primary, include debug info
+	blocks := home.BuildBlocksWithDebug(dashboard, workspaceOrgs[0], mapping)
 
 	// Publish to Slack
 	if err := slackClient.PublishHomeView(ctx, slackUserID, blocks); err != nil {
@@ -177,14 +180,14 @@ func (h *HomeHandler) workspaceOrgs(teamID string) []string {
 }
 
 // publishPlaceholderHome publishes a simple placeholder home view.
-func (*HomeHandler) publishPlaceholderHome(ctx context.Context, slackClient *Client, slackUserID string) error {
+func (*HomeHandler) publishPlaceholderHome(ctx context.Context, slackClient *Client, slackUserID string, mapping *usermapping.ReverseMapping) error {
 	slog.Debug("publishing placeholder home", "user_id", slackUserID)
 
-	blocks := home.BuildBlocks(&home.Dashboard{
+	blocks := home.BuildBlocksWithDebug(&home.Dashboard{
 		IncomingPRs:   nil,
 		OutgoingPRs:   nil,
 		WorkspaceOrgs: []string{"your-org"},
-	}, "your-org")
+	}, "your-org", mapping)
 
 	return slackClient.PublishHomeView(ctx, slackUserID, blocks)
 }