beardrive/cmd/bdrive/hooksync.go

package main

import (
	"encoding/json"
	"fmt"
	"io"
	"path/filepath"
	"strings"
	"time"

	"github.com/spf13/cobra"
)

// `bdrive sync --hook <label>` is the agent-hook flavor of sync, run by the
// Claude Code UserPromptSubmit hook at every turn start. It does three
// things: pulls (a normal cycle), stamps the session note so every change
// this turn is attributed to the agent session, and — the part that keeps
// agents current no matter how stale their skill copy is — emits the
// project's gated-link formula as additionalContext, so the agent can
// append a hub link to any synced file path it mentions.
//
// One run can cover several mounts (a repo root whose wiki/ and docs/ are
// separate projects, see syncTargets), and the hook's stdout contract is a
// single JSON object — so every mount's link goes into one context, keyed
// by the path prefix an agent sees. Emitting only the first mount's URL
// made agents hang one project's base URL on another project's paths.
//
// Everything is best-effort: a hook must never fail the turn, so every
// error path is a silent, successful exit.

// hookNoteTTL mirrors `bdrive sync --note-ttl`'s default: the daemon's own
// scans keep stamping this session's changes for a while.
const hookNoteTTL = 30 * time.Minute

// hookLink pairs the path prefix an agent writes with the hub URL that
// prefix maps to.
type hookLink struct {
	prefix string // "wiki/", or "" when the hook ran at or inside the mount
	base   string // https://hub/<project-id>[/<the run folder's subpath>]
}

// hookSessionID reads the platform's event JSON from stdin — once per run,
// since stdin can only be consumed once and the sync loop may cover several
// mounts.
func hookSessionID(cmd *cobra.Command) string {
	data, _ := io.ReadAll(io.LimitReader(cmd.InOrStdin(), 1<<20))
	var event struct {
		SessionID string `json:"session_id"`
	}
	_ = json.Unmarshal(data, &event) // malformed input: just sync
	return event.SessionID
}

// runHookSync syncs one mount and reports its hub base URL, if it has one.
func runHookSync(cmd *cobra.Command, target, sessionID, label string) (string, bool) {
	sess, proj, err := openSession(cmd.Context(), target, true)
	if err != nil {
		return "", false // not a mount / no session: fast no-op
	}
	defer closeSession(sess)

	if sessionID != "" {
		note := label + " session " + sessionID
		if err := sess.Store.SaveNote(note, hookNoteTTL); err == nil {
			sess.Note = note
		}
	}

	// The pull. Offline is fine — the link formula below is still valid
	// for teammates who are online.
	if _, err := sess.Cycle(cmd.Context()); err != nil {
		return "", false // never break the turn
	}
	server, projectID, err := splitHubRemote(proj.Remote)
	if err != nil {
		return "", false // non-hub remote: nothing to link to
	}
	return server + "/" + projectID, true
}

// hookLinkFor places one mount relative to the folder the hook ran in.
// Agents write paths as they see them from that folder, so the mount's
// position there is what turns a path into a URL: a mount BELOW the folder
// contributes a prefix to strip, while a run INSIDE a mount contributes a
// subpath that belongs in the base instead (there is no prefix to strip —
// every path the agent writes is already inside the mount).
func hookLinkFor(folder, target, base string) hookLink {
	// resolvePath: registry paths and the run folder can name the same
	// directory through different symlinks (macOS /tmp).
	rel, err := filepath.Rel(resolvePath(folder), resolvePath(target))
	if err != nil {
		return hookLink{base: base}
	}
	rel = filepath.ToSlash(rel)
	switch {
	case rel == ".":
		return hookLink{base: base}
	case rel == ".." || strings.HasPrefix(rel, "../"):
		sub, err := filepath.Rel(resolvePath(target), resolvePath(folder))
		if err != nil {
			return hookLink{base: base}
		}
		return hookLink{base: base + "/" + encodePathSegments(filepath.ToSlash(sub))}
	default:
		return hookLink{prefix: rel + "/", base: base}
	}
}

// emitHookContext writes the turn's additionalContext — one JSON object, no
// matter how many mounts the run covered.
func emitHookContext(cmd *cobra.Command, links []hookLink) {
	if len(links) == 0 {
		return
	}

	// Shared tail: what the links mean and when NOT to use them.
	const tail = "These links require hub sign-in + project membership, so they are safe to paste anywhere internal. " +
		"Only link files that actually sync (inside the shared scope, not ignored); keep paths inside code blocks or commands plain; give a raw URL only when the user needs to paste it outside this conversation. " +
		"`bdrive share <file>` mints PUBLIC no-account links — use it only when the user explicitly asks for a public link."

	var context string
	if len(links) == 1 && links[0].prefix == "" {
		// The common case: one project, paths already relative to its root.
		// Kept as short as possible — this is paid on every turn.
		b := links[0].base
		context = fmt.Sprintf(
			"beardrive: this folder syncs to %s (the project's hub page; files are at %s/<url-encoded path>). "+
				"Link convention: whenever you mention a synced file's path in prose, append its gated hub link on an emoji, formatted exactly as: `<path>` [🔗](%s/<url-encoded path>) — the path stays plain text, the hyperlink goes on the emoji only. "+
				"The URL path is the file's path relative to this folder, with each segment percent-encoded and the `/` separators left literal. "+
				tail, b, b, b)
	} else {
		parts := make([]string, len(links))
		for i, l := range links {
			p := l.prefix
			if p == "" {
				p = "./"
			}
			parts[i] = fmt.Sprintf("`%s` → %s", p, l.base)
		}
		context = fmt.Sprintf(
			"beardrive: hub URLs for the synced folders here — %s. "+
				"Link convention: whenever you mention a synced file's path in prose, append its gated hub link on an emoji, formatted exactly as: `<path>` [🔗](<that folder's URL>/<url-encoded path within it>) — the path stays plain text, the hyperlink goes on the emoji only. "+
				"Pick the folder whose prefix above matches the path longest, strip that prefix, then percent-encode each remaining segment and leave the `/` separators literal. A path matching none of these folders is not synced — do not link it, and never hang one folder's path on another folder's URL. "+
				tail, strings.Join(parts, ", "))
	}

	out := map[string]any{
		"hookSpecificOutput": map[string]any{
			"hookEventName":     "UserPromptSubmit",
			"additionalContext": context,
		},
	}
	enc, err := json.Marshal(out)
	if err != nil {
		return
	}
	fmt.Fprintln(cmd.OutOrStdout(), string(enc))
}