refactor: migrate monolithic crate to Cargo Workspace with Clean Architecture

Transform the single binary crate into a 9-crate workspace monorepo:

- Root Cargo.toml as [workspace] manager with resolver = "2"
- zesdex-entities: Domain entity types (session, settings, store, message, etc.)
- zesdex-utils: Pure utility functions (error, logger, pagination, slug, clipboard)
- zesdex-dto: Data Transfer Objects for LLM provider API communication
- zesdex-ipc: Unix-socket IPC layer (client/server/framing/protocol)
- zesdex-iam: Identity & Access Management (Clean Architecture: domain/application/infrastructure)
- zesdex-cms: Content Management (Clean Architecture: domain/application/infrastructure)
- zesdex-middleware: HTTP middleware (Auth, CORS, Rate Limiting)
- zesdex-libs: Composition root (AppContext, DB init, JWT, Argon2)
- zesdex-backend: Main binary entry point + seed/migrate binaries
- DevOps: Dockerfile, docker-compose, Nix (flake/shell/default), CI/CD updates
- Remove dead root src/ and src-misc/ directories

All crate re-exports maintain backward compatibility with original
crate::model::*, crate::dto::*, crate::ipc::* module paths.
Feature crates enforce strict layer separation: domain -> application
-> infrastructure with generic trait-based dependency injection.

crates/zesdex-backend/src/app/subagent/division.rs

@@ -0,0 +1,150 @@
+//! Access tiers for the anonymous processing nodes spawned by the
+//! hive-mind orchestrator (`app::workflow::hive_mind`).
+//!
+//! Nodes have no persistent identity of their own — the Core Intelligence
+//! addresses each one only by directive and access tier. Since node
+//! designations are system-assigned coordinates rather than named roles,
+//! tool access can't be a lookup table keyed by role name. Instead the
+//! Core Intelligence picks one of these three tiers per node, matched to
+//! what that node's specific directive needs — this keeps the Harness
+//! gate meaningful while the node roster itself stays fully dynamic.
+
+/// The three tool-access tiers a hive-mind node can be granted.
+pub mod tool_scope {
+    /// Read-only investigation: no file mutation, no shell, no VCS.
+    pub const READ: &str = "read";
+    /// Read-tier plus file mutation and non-destructive shell (tests/builds).
+    pub const WRITE: &str = "write";
+    /// Write-tier plus delete, git, and the remaining LSP actions.
+    pub const FULL: &str = "full";
+
+    /// The read-only tool set — reused by `context::dedup` as the
+    /// authoritative "safe to deduplicate" classification, so there's a
+    /// single list of read-only tool names in the codebase instead of two.
+    pub const READ_TOOLS: &[&str] = &[
+        "read",
+        "grep",
+        "glob",
+        "search",
+        "seqthink",
+        "recall",
+        "lsp_connect",
+        "lsp_diagnostics",
+        "lsp_hover",
+        "lsp_definition",
+        "lsp_references",
+        "read_findings",
+    ];
+
+    const WRITE_TOOLS: &[&str] = &[
+        "read",
+        "grep",
+        "glob",
+        "search",
+        "seqthink",
+        "recall",
+        "lsp_connect",
+        "lsp_diagnostics",
+        "lsp_hover",
+        "lsp_definition",
+        "lsp_references",
+        "read_findings",
+        "write",
+        "edit",
+        "bash",
+        "todowrite",
+        "todofinish",
+        "remember",
+    ];
+
+    const FULL_TOOLS: &[&str] = &[
+        "read",
+        "grep",
+        "glob",
+        "search",
+        "seqthink",
+        "recall",
+        "lsp_connect",
+        "lsp_diagnostics",
+        "lsp_hover",
+        "lsp_definition",
+        "lsp_references",
+        "read_findings",
+        "write",
+        "edit",
+        "bash",
+        "todowrite",
+        "todofinish",
+        "remember",
+        "delete",
+        "git_operator",
+        "lsp_completion",
+        "lsp_disconnect",
+    ];
+
+    /// Resolve a tier name to its concrete tool allowlist.
+    ///
+    /// Unrecognized scope strings fall back to `READ` — the least-privileged
+    /// tier — rather than silently granting broader access.
+    ///
+    /// Return: an owned `Vec<String>` suitable for `AgentDefinition::with_allowed_tools`.
+    pub fn tools_for(scope: &str) -> Vec<String> {
+        let tools: &[&str] = match scope {
+            FULL => FULL_TOOLS,
+            WRITE => WRITE_TOOLS,
+            _ => READ_TOOLS,
+        };
+        tools.iter().map(|s| (*s).to_string()).collect()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::tool_scope::{tools_for, FULL, READ, WRITE};
+
+    #[test]
+    fn read_tier_excludes_write_tools() {
+        let tools = tools_for(READ);
+        assert!(!tools.contains(&"write".to_string()));
+        assert!(!tools.contains(&"bash".to_string()));
+    }
+
+    #[test]
+    fn write_tier_includes_bash_but_not_delete_or_git() {
+        let tools = tools_for(WRITE);
+        assert!(tools.contains(&"bash".to_string()));
+        assert!(tools.contains(&"write".to_string()));
+        assert!(!tools.contains(&"delete".to_string()));
+        assert!(!tools.contains(&"git_operator".to_string()));
+    }
+
+    #[test]
+    fn full_tier_includes_delete_and_git() {
+        let tools = tools_for(FULL);
+        assert!(tools.contains(&"delete".to_string()));
+        assert!(tools.contains(&"git_operator".to_string()));
+    }
+
+    #[test]
+    fn unknown_scope_falls_back_to_read() {
+        let tools = tools_for("bogus");
+        assert!(!tools.contains(&"write".to_string()));
+        assert!(!tools.contains(&"delete".to_string()));
+    }
+
+    #[test]
+    fn read_tier_is_subset_of_write_tier_and_write_is_subset_of_full() {
+        use std::collections::HashSet;
+        let read: HashSet<_> = tools_for(READ).into_iter().collect();
+        let write: HashSet<_> = tools_for(WRITE).into_iter().collect();
+        let full: HashSet<_> = tools_for(FULL).into_iter().collect();
+        assert!(
+            read.is_subset(&write),
+            "read tier must be a subset of write tier"
+        );
+        assert!(
+            write.is_subset(&full),
+            "write tier must be a subset of full tier"
+        );
+    }
+}