feat: modernise to Go 1.26 iterators and stdlib helpers

Add iter.Seq iterators for Poller, Spinner, and Journal. Use
slices.Sort, slices.SortFunc, maps.DeleteFunc for cleaner
collection operations.

Co-Authored-By: Gemini <noreply@google.com>
Co-Authored-By: Virgil <virgil@lethean.io>

clotho.go

@@ -2,6 +2,7 @@ package agent
 
 import (
 	"context"
+	"iter"
 	"strings"
 
 	"forge.lthn.ai/core/go-agent/jobrunner"
@@ -61,6 +62,17 @@ func (s *Spinner) GetVerifierModel(agentName string) string {
 	return agent.VerifyModel
 }
 
+// Agents returns an iterator over the configured agents.
+func (s *Spinner) AgentsSeq() iter.Seq2[string, AgentConfig] {
+	return func(yield func(string, AgentConfig) bool) {
+		for name, agent := range s.Agents {
+			if !yield(name, agent) {
+				return
+			}
+		}
+	}
+}
+
 // FindByForgejoUser resolves a Forgejo username to the agent config key and config.
 // This decouples agent naming (mythological roles) from Forgejo identity.
 func (s *Spinner) FindByForgejoUser(forgejoUser string) (string, AgentConfig, bool) {
@@ -72,7 +84,7 @@ func (s *Spinner) FindByForgejoUser(forgejoUser string) (string, AgentConfig, bo
 		return forgejoUser, agent, true
 	}
 	// Search by ForgejoUser field.
-	for name, agent := range s.Agents {
+	for name, agent := range s.AgentsSeq() {
 		if agent.ForgejoUser != "" && agent.ForgejoUser == forgejoUser {
 			return name, agent, true
 		}

cmd/dispatch/cmd.go

@@ -10,7 +10,7 @@ import (
 	"os/exec"
 	"os/signal"
 	"path/filepath"
-	"sort"
+	"slices"
 	"strconv"
 	"strings"
 	"syscall"
@@ -674,6 +674,6 @@ func pickOldestTicket(queueDir string) (string, error) {
 		return "", nil
 	}
 
-	sort.Strings(tickets)
+	slices.Sort(tickets)
 	return tickets[0], nil
 }

cmd/mcp/plugin_info.go

@@ -5,7 +5,7 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
-	"sort"
+	"slices"
 
 	"github.com/mark3labs/mcp-go/mcp"
 )
@@ -75,7 +75,7 @@ func listCommands(path string) ([]string, error) {
 		return nil
 	})
 
-	sort.Strings(commands)
+	slices.Sort(commands)
 	return commands, nil
 }
 
@@ -98,7 +98,7 @@ func listSkills(path string) ([]string, error) {
 		}
 	}
 
-	sort.Strings(skills)
+	slices.Sort(skills)
 	return skills, nil
 }
 

config.go

@@ -3,6 +3,7 @@ package agent
 
 import (
 	"fmt"
+	"maps"
 
 	"forge.lthn.ai/core/go/pkg/config"
 )
@@ -61,16 +62,13 @@ func LoadAgents(cfg *config.Config) (map[string]AgentConfig, error) {
 
 // LoadActiveAgents returns only active agents.
 func LoadActiveAgents(cfg *config.Config) (map[string]AgentConfig, error) {
-	all, err := LoadAgents(cfg)
+	active, err := LoadAgents(cfg)
 	if err != nil {
 		return nil, err
 	}
-	active := make(map[string]AgentConfig)
-	for name, ac := range all {
-		if ac.Active {
-			active[name] = ac
-		}
-	}
+	maps.DeleteFunc(active, func(_ string, ac AgentConfig) bool {
+		return !ac.Active
+	})
 	return active, nil
 }
 

jobrunner/handlers/dispatch.go

@@ -107,7 +107,7 @@ func (h *DispatchHandler) Execute(ctx context.Context, signal *jobrunner.Pipelin
 	if err == nil {
 		for _, l := range issue.Labels {
 			if l.Name == LabelInProgress || l.Name == LabelAgentComplete {
-				log.Info("issue already processed, skipping", "issue", signal.ChildNumber, "label", l.Name)
+				log.Info("issue already processed, skipping", "issue", signal.ChildNumber)
 				return &jobrunner.ActionResult{
 					Action:    "dispatch",
 					Success:   true,

jobrunner/journal.go

@@ -1,8 +1,10 @@
 package jobrunner
 
 import (
+	"bufio"
 	"encoding/json"
 	"fmt"
+	"iter"
 	"os"
 	"path/filepath"
 	"regexp"
@@ -87,6 +89,35 @@ func sanitizePathComponent(name string) (string, error) {
 	return clean, nil
 }
 
+// ReadEntries returns an iterator over JournalEntry lines in a date-partitioned file.
+func (j *Journal) ReadEntries(path string) iter.Seq2[JournalEntry, error] {
+	return func(yield func(JournalEntry, error) bool) {
+		f, err := os.Open(path)
+		if err != nil {
+			yield(JournalEntry{}, err)
+			return
+		}
+		defer func() { _ = f.Close() }()
+
+		scanner := bufio.NewScanner(f)
+		for scanner.Scan() {
+			var entry JournalEntry
+			if err := json.Unmarshal(scanner.Bytes(), &entry); err != nil {
+				if !yield(JournalEntry{}, err) {
+					return
+				}
+				continue
+			}
+			if !yield(entry, nil) {
+				return
+			}
+		}
+		if err := scanner.Err(); err != nil {
+			yield(JournalEntry{}, err)
+		}
+	}
+}
+
 // Append writes a journal entry for the given signal and result.
 func (j *Journal) Append(signal *PipelineSignal, result *ActionResult) error {
 	if signal == nil {

jobrunner/poller.go

@@ -2,6 +2,7 @@ package jobrunner
 
 import (
 	"context"
+	"iter"
 	"sync"
 	"time"
 
@@ -51,6 +52,38 @@ func (p *Poller) Cycle() int {
 	return p.cycle
 }
 
+// Sources returns an iterator over the poller's sources.
+func (p *Poller) Sources() iter.Seq[JobSource] {
+	return func(yield func(JobSource) bool) {
+		p.mu.RLock()
+		sources := make([]JobSource, len(p.sources))
+		copy(sources, p.sources)
+		p.mu.RUnlock()
+
+		for _, s := range sources {
+			if !yield(s) {
+				return
+			}
+		}
+	}
+}
+
+// Handlers returns an iterator over the poller's handlers.
+func (p *Poller) Handlers() iter.Seq[JobHandler] {
+	return func(yield func(JobHandler) bool) {
+		p.mu.RLock()
+		handlers := make([]JobHandler, len(p.handlers))
+		copy(handlers, p.handlers)
+		p.mu.RUnlock()
+
+		for _, h := range handlers {
+			if !yield(h) {
+				return
+			}
+		}
+	}
+}
+
 // DryRun returns whether dry-run mode is enabled.
 func (p *Poller) DryRun() bool {
 	p.mu.RLock()
@@ -109,15 +142,11 @@ func (p *Poller) RunOnce(ctx context.Context) error {
 	p.cycle++
 	cycle := p.cycle
 	dryRun := p.dryRun
-	sources := make([]JobSource, len(p.sources))
-	copy(sources, p.sources)
-	handlers := make([]JobHandler, len(p.handlers))
-	copy(handlers, p.handlers)
 	p.mu.Unlock()
 
-	log.Info("poller cycle starting", "cycle", cycle, "sources", len(sources), "handlers", len(handlers))
+	log.Info("poller cycle starting", "cycle", cycle)
 
-	for _, src := range sources {
+	for src := range p.Sources() {
 		signals, err := src.Poll(ctx)
 		if err != nil {
 			log.Error("poll failed", "source", src.Name(), "err", err)
@@ -127,7 +156,7 @@ func (p *Poller) RunOnce(ctx context.Context) error {
 		log.Info("polled source", "source", src.Name(), "signals", len(signals))
 
 		for _, sig := range signals {
-			handler := p.findHandler(handlers, sig)
+			handler := p.findHandler(p.Handlers(), sig)
 			if handler == nil {
 				log.Debug("no matching handler", "epic", sig.EpicNumber, "child", sig.ChildNumber)
 				continue
@@ -185,8 +214,8 @@ func (p *Poller) RunOnce(ctx context.Context) error {
 }
 
 // findHandler returns the first handler that matches the signal, or nil.
-func (p *Poller) findHandler(handlers []JobHandler, sig *PipelineSignal) JobHandler {
-	for _, h := range handlers {
+func (p *Poller) findHandler(handlers iter.Seq[JobHandler], sig *PipelineSignal) JobHandler {
+	for h := range handlers {
 		if h.Match(sig) {
 			return h
 		}