Define mirror targets one way: remote.<name>.<field>

There were two spellings for the same thing -- a flat
remoteurl/remotekey/remotetype/remotevisibility set for a single server,
and remote.<name>.* blocks for several. The flat one is gone; every
target, including a lone one, is now a named block with the fields url,
key, type and visibility.

An existing ~/.mgshrc is converted on the next start. Only the key is
rewritten, so values, comments, alignment, commented-out lines and the
file's 0600 mode survive untouched, and mgsh prints each rename rather
than doing it quietly. The target is named "public", which is what the
old settings called the git remote they created, so a converted setup
keeps pushing to the same place under the same remote name. A file that
carries both spellings keeps what the new one says.

The environment follows the same shape: MGSH_REMOTEURL and friends are
replaced by MGSH_REMOTE_<NAME>_<FIELD>, so MGSH_REMOTE_GITLAB_KEY sets
remote.gitlab.key. The field is read from the end of the variable name,
which leaves target names free to contain underscores.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

config.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"path/filepath"
 	"regexp"
+	"slices"
 	"sort"
 	"strings"
 )
@@ -33,10 +34,6 @@ type Config struct {
 	GitEmail    string // git user.email to set globally ("" = leave alone)
 	PushDefault string // git push.default to set globally ("" = leave alone)
 	Editor      string // editor/opener used as fallback by `open` ("" = coda)
-	RemoteURL   string // public mirror server base URL (Gitea/GitHub/GitLab)
-	RemoteKey   string // API token for the mirror server (used by `pushremote`)
-	RemoteType  string // "gitea"|"github"|"gitlab" (auto-detected when empty)
-	RemoteVis   string // visibility of created repos: "private" (default)|"public"
 	Mirror      string // truthy -> `push` also mirrors via `pushremote`
 	SecretScan  string // falsy -> `push` skips the credential scan
 	Remotes     []RemoteTarget
@@ -54,22 +51,25 @@ type RemoteTarget struct {
 	Vis  string // "private" (default) | "public"
 }
 
-// legacyRemoteName is the target name for the flat remoteurl/remotekey pair,
-// matching the git remote that earlier versions created.
+// legacyRemoteName is the target the pre-4.1 flat remoteurl/remotekey settings
+// are migrated to. It matches the git remote those versions created, so a
+// converted configuration keeps pushing to the same place.
 const legacyRemoteName = "public"
 
+// legacyRemoteKeys maps the old flat spelling onto the named-target form. A
+// mirror target is defined one way now, not two.
+var legacyRemoteKeys = map[string]string{
+	"remoteurl":        "remote." + legacyRemoteName + ".url",
+	"remotekey":        "remote." + legacyRemoteName + ".key",
+	"remotetype":       "remote." + legacyRemoteName + ".type",
+	"remotevisibility": "remote." + legacyRemoteName + ".visibility",
+}
+
 // mirrorTargets returns the usable mirror targets in configured order, plus the
 // names of targets that are defined but unusable (missing url or key) so the
 // caller can complain about them instead of silently skipping.
 func (c Config) mirrorTargets() (usable []RemoteTarget, incomplete []string) {
-	var all []RemoteTarget
-	if c.RemoteURL != "" || c.RemoteKey != "" {
-		all = append(all, RemoteTarget{
-			Name: legacyRemoteName, URL: c.RemoteURL, Key: c.RemoteKey,
-			Type: c.RemoteType, Vis: c.RemoteVis,
-		})
-	}
-	all = append(all, c.Remotes...)
+	all := c.Remotes
 
 	// `remotes = a, b` narrows and orders the set — a project .mgshrc uses it
 	// to mirror to only some of the globally configured servers.
@@ -147,11 +147,54 @@ func loadConfig() Config {
 		m := parseConfig(string(data))
 		applyConfig(&c, m)
 		warnConfigPerms(path, m)
+		migrateRemoteKeys(path, string(data))
 	}
 	applyEnv(&c)
 	return c
 }
 
+// migrateRemoteKeys converts the pre-4.1 flat remote settings in a config file
+// to the remote.<name>.<field> spelling, so a mirror target is defined one way
+// and not two. Only the key is rewritten: values, comments, blank lines and the
+// file's permissions stay exactly as they are, and commented-out lines are left
+// alone. Reports what it changed rather than doing it silently.
+func migrateRemoteKeys(path, data string) {
+	lines := strings.Split(data, "\n")
+	var renamed []string
+
+	for i, ln := range lines {
+		trimmed := strings.TrimLeft(ln, " \t")
+		if trimmed == "" || strings.HasPrefix(trimmed, "#") {
+			continue
+		}
+		sep := strings.IndexAny(trimmed, "=:")
+		if sep < 0 {
+			continue
+		}
+		key := strings.TrimRight(trimmed[:sep], " \t")
+		dotted, ok := legacyRemoteKeys[strings.ToLower(key)]
+		if !ok {
+			continue
+		}
+		indent := ln[:len(ln)-len(trimmed)]
+		gap := trimmed[len(key):sep] // whatever alignment was there
+		lines[i] = indent + dotted + gap + trimmed[sep:]
+		renamed = append(renamed, key+" → "+dotted)
+	}
+	if len(renamed) == 0 {
+		return
+	}
+
+	if err := os.WriteFile(path, []byte(strings.Join(lines, "\n")), configMode); err != nil {
+		errorln("could not update " + path + ": " + err.Error())
+		return
+	}
+	fmt.Println(col(cGray, path+": mirror settings renamed to the remote.<name>.* form"))
+	for _, r := range renamed {
+		fmt.Println(col(cGray, "  "+r))
+	}
+}
+
 // projectGlobalOnly lists settings a project-level .mgshrc must not change:
 // `base` decides where projects live in the first place, and the git identity
 // keys are written to the user's *global* git config at startup — applying
@@ -279,13 +322,15 @@ func writeConfigTemplate(path string) {
 	b.WriteString("# pushdefault = matching\n")
 	b.WriteString("# editor      = code\n\n")
 	b.WriteString("# --- public mirrors for `pushremote` ---\n")
-	b.WriteString("# One block per server; `pushremote` pushes to all of them,\n")
-	b.WriteString("# `pushremote @hub` to a single one.\n")
-	b.WriteString("# remote.hub.url        = https://github.com\n")
-	b.WriteString("# remote.hub.key        = <personal-access-token>\n")
-	b.WriteString("# remote.hub.visibility = public\n")
-	b.WriteString("# remotes               = hub    # optional: restrict/order the set\n")
-	b.WriteString("# mirror                = true   # `push` also mirrors\n\n")
+	b.WriteString("# One 'remote.<name>.*' block per server. `pushremote` pushes to all\n")
+	b.WriteString("# of them, `pushremote @gitlab` to a single one. <name> is also the\n")
+	b.WriteString("# git remote created in the repository.\n")
+	b.WriteString("# remote.gitlab.url        = https://gitlab.example.com\n")
+	b.WriteString("# remote.gitlab.key        = <personal-access-token>\n")
+	b.WriteString("# remote.gitlab.type       = gitlab   # optional; detected from the url\n")
+	b.WriteString("# remote.gitlab.visibility = private  # or public (default private)\n")
+	b.WriteString("# remotes                  = gitlab   # optional: restrict/order the set\n")
+	b.WriteString("# mirror                   = true     # `push` also mirrors\n\n")
 	b.WriteString("# A project may override any of these (except base and the git\n")
 	b.WriteString("# identity) in its own <project>/.mgshrc.\n")
 
@@ -365,14 +410,36 @@ func applyConfig(c *Config, m map[string]string) {
 	set("gitemail", &c.GitEmail)
 	set("pushdefault", &c.PushDefault)
 	set("editor", &c.Editor)
-	set("remoteurl", &c.RemoteURL)
-	set("remotekey", &c.RemoteKey)
-	set("remotetype", &c.RemoteType)
-	set("remotevisibility", &c.RemoteVis)
 	set("remotes", &c.RemoteNames)
 	set("mirror", &c.Mirror)
 	set("secretscan", &c.SecretScan)
-	applyRemoteTargets(c, m)
+	applyRemoteTargets(c, foldLegacyRemoteKeys(m))
+}
+
+// foldLegacyRemoteKeys rewrites the pre-4.1 flat remote settings into the
+// named-target form, so a configuration that has not been converted yet still
+// works while it is being read. The file itself is converted by
+// migrateRemoteKeys; this only makes the current run behave.
+func foldLegacyRemoteKeys(m map[string]string) map[string]string {
+	folded, copied := m, false
+	for old, dotted := range legacyRemoteKeys {
+		v, ok := m[old]
+		if !ok || v == "" {
+			continue
+		}
+		if _, taken := m[dotted]; taken {
+			continue // an explicit new-style setting always wins
+		}
+		if !copied { // copy on first write, never touch the caller's map
+			folded = make(map[string]string, len(m))
+			for k, val := range m {
+				folded[k] = val
+			}
+			copied = true
+		}
+		folded[dotted] = v
+	}
+	return folded
 }
 
 // remoteFieldRe matches a named mirror target setting: remote.<name>.<field>.
@@ -439,11 +506,55 @@ func applyEnv(c *Config) {
 	env("MGSH_GITEMAIL", &c.GitEmail)
 	env("MGSH_PUSHDEFAULT", &c.PushDefault)
 	env("MGSH_EDITOR", &c.Editor)
-	env("MGSH_REMOTEURL", &c.RemoteURL)
-	env("MGSH_REMOTEKEY", &c.RemoteKey)
-	env("MGSH_REMOTETYPE", &c.RemoteType)
-	env("MGSH_REMOTEVISIBILITY", &c.RemoteVis)
 	env("MGSH_REMOTES", &c.RemoteNames)
 	env("MGSH_MIRROR", &c.Mirror)
 	env("MGSH_SECRETSCAN", &c.SecretScan)
+	applyRemoteEnv(c)
+}
+
+// remoteFields are the settings a mirror target is made of.
+var remoteFields = []string{"url", "key", "type", "visibility"}
+
+// applyRemoteEnv reads MGSH_REMOTE_<NAME>_<FIELD>, the environment spelling of
+// a remote.<name>.<field> setting — MGSH_REMOTE_GITLAB_KEY for
+// remote.gitlab.key. The field is taken from the end, so a target name may
+// contain underscores itself.
+func applyRemoteEnv(c *Config) {
+	const prefix = "MGSH_REMOTE_"
+
+	// sorted, so a target these variables introduce lands in the push order the
+	// same way on every run
+	envs := os.Environ()
+	sort.Strings(envs)
+
+	for _, kv := range envs {
+		eq := strings.IndexByte(kv, '=')
+		if eq < 0 {
+			continue
+		}
+		name, value := kv[:eq], kv[eq+1:]
+		if value == "" || !strings.HasPrefix(name, prefix) {
+			continue
+		}
+		rest := name[len(prefix):]
+		us := strings.LastIndexByte(rest, '_')
+		if us <= 0 {
+			continue
+		}
+		target, field := strings.ToLower(rest[:us]), strings.ToLower(rest[us+1:])
+		if !slices.Contains(remoteFields, field) {
+			continue // MGSH_REMOTES and anything else that merely starts alike
+		}
+		t := &c.Remotes[c.remoteIndex(target)]
+		switch field {
+		case "url":
+			t.URL = value
+		case "key":
+			t.Key = value
+		case "type":
+			t.Type = value
+		case "visibility":
+			t.Vis = value
+		}
+	}
 }