refactor(executor): extract provider-neutral tool-use loop (Phase 1)

Splits LocalRunner's OpenAI-specific agentic loop into reusable, provider-
agnostic pieces so later phases can add native Anthropic/OpenAI/Google/Groq/
OpenRouter adapters without duplicating the control flow:

- internal/provider: neutral Provider/ChatRequest/ChatResponse types, plus
  an openaicompat adapter wrapping the existing internal/llm.Client unchanged
- internal/sandbox: Sandbox interface + HostSandbox (git clone/push/cleanup,
  read_file/write_file/run_bash/glob), lifted verbatim from local.go/localtools.go
- internal/agentloop: the extracted tool-use loop (request/response/tool-
  dispatch/loop, ask_user blocking, stream-json envelope, summary fallback)
- internal/agentchannel: AgentChannel/SubtaskSpec/BlockedError/ErrAgentBlocked
  moved out of internal/executor so agentloop can use them without an import
  cycle; internal/executor re-exports via type aliases, so no call site changes
- internal/executor/nativerunner.go: NativeRunner replaces LocalRunner,
  wiring agentloop.Loop + openaicompat + HostSandbox together
- config.Providers map[string]ProviderConfig added (unused until Phase 2+)

Zero intended behavior change: go test -race ./... passes across all
packages, and end-to-end stream-json/summary/changestats output was verified
byte-compatible against a fake OpenAI-compatible server. Adds test coverage
for sandbox tool-dispatch (git clone/push, read/write/bash/glob) that
LocalRunner never had.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01V1moSNCJRcP6kykA4tyUSs

1 files changed, 226 insertions, 0 deletions

diff --git a/internal/agentloop/tools.go b/internal/agentloop/tools.go
new file mode 100644
index 0000000..e92a12f
--- /dev/null
+++ b/internal/agentloop/tools.go
@@ -0,0 +1,226 @@
+package agentloop
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+
+	"github.com/thepeterstone/claudomator/internal/agentchannel"
+	"github.com/thepeterstone/claudomator/internal/provider"
+)
+
+// agentToolSpecs returns the eight tools available to the loop: the four
+// agent back-channel tools (mirroring the MCP tools ContainerRunner exposes)
+// plus the four sandbox tools, as provider-neutral ToolSpecs. Ported verbatim
+// (same names/descriptions/JSON schemas) from the former
+// executor.agentToolDefs (internal/executor/localtools.go).
+func agentToolSpecs() []provider.ToolSpec {
+	strProp := func(desc string) map[string]any {
+		return map[string]any{"type": "string", "description": desc}
+	}
+	return []provider.ToolSpec{
+		{
+			Name:        "ask_user",
+			Description: "Ask the user a question when you genuinely need a decision to proceed. The task pauses until the user answers; do not call other tools after this.",
+			ParametersJSONSchema: map[string]any{
+				"type": "object",
+				"properties": map[string]any{
+					"question": strProp("the question to ask, phrased as a real question"),
+					"options":  map[string]any{"type": "array", "items": map[string]any{"type": "string"}, "description": "optional suggested answer choices"},
+				},
+				"required": []string{"question"},
+			},
+		},
+		{
+			Name:        "report_summary",
+			Description: "Record a concise 2-5 sentence summary of what you accomplished. Call this before finishing.",
+			ParametersJSONSchema: map[string]any{
+				"type":       "object",
+				"properties": map[string]any{"summary": strProp("the summary text")},
+				"required":   []string{"summary"},
+			},
+		},
+		{
+			Name:        "spawn_subtask",
+			Description: "Create a child task to be executed separately. Use this to break large work into focused pieces.",
+			ParametersJSONSchema: map[string]any{
+				"type": "object",
+				"properties": map[string]any{
+					"name":           strProp("short descriptive name for the subtask"),
+					"instructions":   strProp("complete instructions for the subtask agent"),
+					"model":          strProp("optional model override"),
+					"max_budget_usd": map[string]any{"type": "number", "description": "optional budget cap in USD"},
+				},
+				"required": []string{"name", "instructions"},
+			},
+		},
+		{
+			Name:        "record_progress",
+			Description: "Record a short progress note that appears in the task timeline.",
+			ParametersJSONSchema: map[string]any{
+				"type":       "object",
+				"properties": map[string]any{"message": strProp("a short progress note")},
+				"required":   []string{"message"},
+			},
+		},
+		{
+			Name:        "read_file",
+			Description: "Read the contents of a file in the sandbox working directory.",
+			ParametersJSONSchema: map[string]any{
+				"type":       "object",
+				"properties": map[string]any{"path": strProp("path to the file, relative or absolute")},
+				"required":   []string{"path"},
+			},
+		},
+		{
+			Name:        "write_file",
+			Description: "Write or overwrite a file in the sandbox working directory.",
+			ParametersJSONSchema: map[string]any{
+				"type": "object",
+				"properties": map[string]any{
+					"path":    strProp("path to the file, relative or absolute"),
+					"content": strProp("content to write"),
+				},
+				"required": []string{"path", "content"},
+			},
+		},
+		{
+			Name:        "run_bash",
+			Description: "Run a shell command in the sandbox working directory. Returns exit code, stdout, and stderr.",
+			ParametersJSONSchema: map[string]any{
+				"type":       "object",
+				"properties": map[string]any{"command": strProp("shell command to execute")},
+				"required":   []string{"command"},
+			},
+		},
+		{
+			Name:        "glob",
+			Description: "List files matching a glob pattern relative to the sandbox working directory.",
+			ParametersJSONSchema: map[string]any{
+				"type":       "object",
+				"properties": map[string]any{"pattern": strProp("glob pattern, e.g. **/*.go")},
+				"required":   []string{"pattern"},
+			},
+		},
+	}
+}
+
+// dispatchTool invokes one model-requested tool. Back-channel tools
+// (ask_user/report_summary/spawn_subtask/record_progress) go to l.Channel;
+// sandbox tools (read_file/write_file/run_bash/glob) go to l.Sandbox. It
+// returns the text to feed back to the model as the tool result, and a
+// blocked flag set when ask_user could not be answered in-session (the run
+// must stop and the task block). Ported from the former
+// executor.dispatchAgentTool (internal/executor/localtools.go), preserving
+// identical result-string formatting.
+func (l *Loop) dispatchTool(ctx context.Context, name, argsJSON string) (result string, blocked bool, err error) {
+	switch name {
+	case "ask_user":
+		var a struct {
+			Question string   `json:"question"`
+			Options  []string `json:"options"`
+		}
+		_ = json.Unmarshal([]byte(argsJSON), &a)
+		q := map[string]any{"text": a.Question}
+		if len(a.Options) > 0 {
+			q["options"] = a.Options
+		}
+		payload, _ := json.Marshal(q)
+		ans, askErr := l.Channel.AskUser(ctx, string(payload))
+		if errors.Is(askErr, agentchannel.ErrAgentBlocked) {
+			return "", true, nil
+		}
+		if askErr != nil {
+			return "", false, askErr
+		}
+		return ans, false, nil
+
+	case "report_summary":
+		var a struct {
+			Summary string `json:"summary"`
+		}
+		_ = json.Unmarshal([]byte(argsJSON), &a)
+		if rsErr := l.Channel.ReportSummary(ctx, a.Summary); rsErr != nil {
+			return "", false, rsErr
+		}
+		return "Summary recorded.", false, nil
+
+	case "spawn_subtask":
+		var a struct {
+			Name         string  `json:"name"`
+			Instructions string  `json:"instructions"`
+			Model        string  `json:"model"`
+			MaxBudgetUSD float64 `json:"max_budget_usd"`
+		}
+		_ = json.Unmarshal([]byte(argsJSON), &a)
+		id, ssErr := l.Channel.SpawnSubtask(ctx, agentchannel.SubtaskSpec{
+			Name:         a.Name,
+			Instructions: a.Instructions,
+			Model:        a.Model,
+			MaxBudgetUSD: a.MaxBudgetUSD,
+		})
+		if ssErr != nil {
+			return "", false, ssErr
+		}
+		return "Created subtask " + id, false, nil
+
+	case "record_progress":
+		var a struct {
+			Message string `json:"message"`
+		}
+		_ = json.Unmarshal([]byte(argsJSON), &a)
+		if rpErr := l.Channel.RecordProgress(ctx, a.Message); rpErr != nil {
+			return "", false, rpErr
+		}
+		return "Noted.", false, nil
+
+	case "read_file":
+		var a struct {
+			Path string `json:"path"`
+		}
+		_ = json.Unmarshal([]byte(argsJSON), &a)
+		content, readErr := l.Sandbox.ReadFile(ctx, a.Path)
+		if readErr != nil {
+			return "", false, readErr
+		}
+		return content, false, nil
+
+	case "write_file":
+		var a struct {
+			Path    string `json:"path"`
+			Content string `json:"content"`
+		}
+		_ = json.Unmarshal([]byte(argsJSON), &a)
+		if writeErr := l.Sandbox.WriteFile(ctx, a.Path, a.Content); writeErr != nil {
+			return "", false, writeErr
+		}
+		return "Written.", false, nil
+
+	case "run_bash":
+		var a struct {
+			Command string `json:"command"`
+		}
+		_ = json.Unmarshal([]byte(argsJSON), &a)
+		out, errOut, exitCode, runErr := l.Sandbox.RunBash(ctx, a.Command)
+		if runErr != nil {
+			return "", false, runErr
+		}
+		return fmt.Sprintf("exit_code: %d\nstdout:\n%s\nstderr:\n%s", exitCode, out, errOut), false, nil
+
+	case "glob":
+		var a struct {
+			Pattern string `json:"pattern"`
+		}
+		_ = json.Unmarshal([]byte(argsJSON), &a)
+		matches, globErr := l.Sandbox.Glob(ctx, a.Pattern)
+		if globErr != nil {
+			return "", false, globErr
+		}
+		out, _ := json.Marshal(matches)
+		return string(out), false, nil
+
+	default:
+		return "", false, fmt.Errorf("unknown tool %q", name)
+	}
+}