feat(tools): implement CRUD operations for thoughts and projects

* Add tools for creating, retrieving, updating, and deleting thoughts.
* Implement project management tools for creating and listing projects.
* Introduce linking functionality between thoughts.
* Add search and recall capabilities for thoughts based on semantic queries.
* Implement statistics and summarization tools for thought analysis.
* Create database migrations for thoughts, projects, and links.
* Add helper functions for UUID parsing and project resolution.

internal/tools/recall.go

@@ -0,0 +1,111 @@
+package tools
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"github.com/google/uuid"
+	"github.com/modelcontextprotocol/go-sdk/mcp"
+
+	"git.warky.dev/wdevs/amcs/internal/ai"
+	"git.warky.dev/wdevs/amcs/internal/config"
+	"git.warky.dev/wdevs/amcs/internal/session"
+	"git.warky.dev/wdevs/amcs/internal/store"
+)
+
+type RecallTool struct {
+	store    *store.DB
+	provider ai.Provider
+	search   config.SearchConfig
+	sessions *session.ActiveProjects
+}
+
+type RecallInput struct {
+	Query   string `json:"query" jsonschema:"semantic query for recalled context"`
+	Project string `json:"project,omitempty" jsonschema:"optional project name or id; falls back to the active session project"`
+	Limit   int    `json:"limit,omitempty" jsonschema:"maximum number of context items to return"`
+}
+
+type RecallOutput struct {
+	Context string        `json:"context"`
+	Items   []ContextItem `json:"items"`
+}
+
+func NewRecallTool(db *store.DB, provider ai.Provider, search config.SearchConfig, sessions *session.ActiveProjects) *RecallTool {
+	return &RecallTool{store: db, provider: provider, search: search, sessions: sessions}
+}
+
+func (t *RecallTool) Handle(ctx context.Context, req *mcp.CallToolRequest, in RecallInput) (*mcp.CallToolResult, RecallOutput, error) {
+	query := strings.TrimSpace(in.Query)
+	if query == "" {
+		return nil, RecallOutput{}, errInvalidInput("query is required")
+	}
+
+	project, err := resolveProject(ctx, t.store, t.sessions, req, in.Project, false)
+	if err != nil {
+		return nil, RecallOutput{}, err
+	}
+
+	limit := normalizeLimit(in.Limit, t.search)
+	embedding, err := t.provider.Embed(ctx, query)
+	if err != nil {
+		return nil, RecallOutput{}, err
+	}
+
+	var projectID *uuid.UUID
+	if project != nil {
+		projectID = &project.ID
+	}
+
+	semantic, err := t.store.SearchSimilarThoughts(ctx, embedding, t.search.DefaultThreshold, limit, projectID, nil)
+	if err != nil {
+		return nil, RecallOutput{}, err
+	}
+	recent, err := t.store.RecentThoughts(ctx, projectID, limit, 0)
+	if err != nil {
+		return nil, RecallOutput{}, err
+	}
+
+	items := make([]ContextItem, 0, limit*2)
+	seen := map[string]struct{}{}
+	for _, result := range semantic {
+		key := result.ID.String()
+		seen[key] = struct{}{}
+		items = append(items, ContextItem{
+			ID:         key,
+			Content:    result.Content,
+			Metadata:   result.Metadata,
+			Similarity: result.Similarity,
+			Source:     "semantic",
+		})
+	}
+	for _, thought := range recent {
+		key := thought.ID.String()
+		if _, ok := seen[key]; ok {
+			continue
+		}
+		seen[key] = struct{}{}
+		items = append(items, ContextItem{
+			ID:       key,
+			Content:  thought.Content,
+			Metadata: thought.Metadata,
+			Source:   "recent",
+		})
+	}
+
+	lines := make([]string, 0, len(items))
+	for i, item := range items {
+		lines = append(lines, thoughtContextLine(i, item.Content, item.Metadata, item.Similarity))
+	}
+	header := "Recalled context"
+	if project != nil {
+		header = fmt.Sprintf("Recalled context for %s", project.Name)
+		_ = t.store.TouchProject(ctx, project.ID)
+	}
+
+	return nil, RecallOutput{
+		Context: formatContextBlock(header, lines),
+		Items:   items,
+	}, nil
+}