claude-code: point the agent at the mesh's tools and guard its shell against ssh to the mesh (hq ADR 0245)

The agent kept running ssh <machine> journalctl while the journal verb existed. The managed
instructions now carry an "instead of" table generated from what each verb says it replaces, and
the plugin carries a PreToolUse guard that refuses ssh to a mesh machine and local work-arounds for a
mesh name, naming the tool or saying one must be created. The operator's override is read from the
session's start environment and recorded.

modules/claude-code/cmd/claude-code/insteadof.go

@@ -0,0 +1,103 @@
+package main
+
+// The "instead of" table in the agent's managed instructions (novox/hq ADR 0244): to do this, call that
+// address, not this shell command — generated on every render from what each seat verb and module tool
+// says it replaces, so it cannot drift from the tools the mesh has.
+//
+// Short: a row per seat or module, its top what this machine's agent reached round most — the tools the
+// guard named most often in its record.
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+)
+
+// InsteadOfRows is how many rows — seats and modules — the table holds; the rest are one search away.
+const InsteadOfRows = 16
+
+// insteadOrder is the order rows are taken in: a machine's seat, a module on a machine, the mesh's seat.
+func insteadOrder(r Replacement) int {
+	switch {
+	case r.Seat && r.NodeScoped:
+		return 0
+	case !r.Seat:
+		return 1
+	}
+	return 2
+}
+
+func code(s string) string { return "`" + strings.ReplaceAll(s, "`", "'") + "`" }
+
+// insteadGroup is one row: a seat or a module, and its verbs that replace a command.
+type insteadGroup struct {
+	prefix  string // `<node>/node-service-manager.` or `mesh-controller.`
+	verbs   []Replacement
+	refused int
+}
+
+// InsteadOf is the section, or "" when the mesh said nothing replaces anything — an older controller,
+// or one not yet asked.
+//
+// One row per seat or module, every verb of it that replaces a command in the row, so a verb is never cut
+// for being late in its seat's list; the rows the guard here named most come first, then the machines'
+// seats, the modules' tools and the mesh's own seats in the records' order.
+func InsteadOf(m *MeshTools) string {
+	if m == nil || len(m.Replacements) == 0 {
+		return ""
+	}
+	var groups []*insteadGroup
+	at := map[string]*insteadGroup{}
+	for order := 0; order <= 2; order++ {
+		for _, r := range m.Replacements {
+			if insteadOrder(r) != order {
+				continue
+			}
+			prefix := r.Address[:strings.LastIndex(r.Address, ".")+1]
+			if r.NodeScoped {
+				prefix = "<node>/" + prefix
+			}
+			g := at[prefix]
+			if g == nil {
+				g = &insteadGroup{prefix: prefix}
+				at[prefix] = g
+				groups = append(groups, g)
+			}
+			g.verbs = append(g.verbs, r)
+			g.refused += m.Refused[r.Address]
+		}
+	}
+	sort.SliceStable(groups, func(i, j int) bool { return groups[i].refused > groups[j].refused })
+	for _, g := range groups {
+		sort.SliceStable(g.verbs, func(i, j int) bool { return m.Refused[g.verbs[i].Address] > m.Refused[g.verbs[j].Address] })
+	}
+	more := 0
+	if len(groups) > InsteadOfRows {
+		more = len(groups) - InsteadOfRows
+		groups = groups[:InsteadOfRows]
+	}
+	var b strings.Builder
+	b.WriteString("\n## Instead of a shell command\n\n")
+	b.WriteString("Generated from what each seat verb and module tool says it replaces (`replaces`, novox/hq ADR 0244),\n")
+	b.WriteString("rewritten on every render. Call `<address><verb>` through `mesh_call`, `<node>` being the machine;\n")
+	b.WriteString("`mesh_search` with the command you would have typed finds it too.\n\n")
+	b.WriteString("| call | the verb — instead of |\n|---|---|\n")
+	for _, g := range groups {
+		var cells []string
+		for _, r := range g.verbs {
+			var not []string
+			for _, c := range r.Replaces {
+				not = append(not, code(c))
+			}
+			cells = append(cells, code(r.Address[strings.LastIndex(r.Address, ".")+1:])+" — "+strings.Join(not, ", "))
+		}
+		fmt.Fprintf(&b, "| %s | %s |\n", code(g.prefix), strings.ReplaceAll(strings.Join(cells, " · "), "|", "/"))
+	}
+	if more > 0 {
+		fmt.Fprintf(&b, "\n%d more seats and modules: `mesh_search` with the command finds the tool for it.\n", more)
+	}
+	b.WriteString("\n- **Never `ssh` to a mesh machine**, and never edit `/etc/hosts` or set `HOSTALIASES` for a mesh\n" +
+		"  name: the guard on this session's shell refuses it and names the tool. Where no tool covers what you\n" +
+		"  need, none is worked around: say so, and the tool is created in the module that owns it, on its seat.\n")
+	return b.String()
+}