diff --git a/docs/SUMMARY.md b/docs/SUMMARY.md
index 61542f9..93b36a1 100644
--- a/docs/SUMMARY.md
+++ b/docs/SUMMARY.md
@@ -38,5 +38,8 @@
 
 * [CLI reference](reference-and-help/cli-reference.md)
 * [Config reference](reference-and-help/config-reference.md)
+* [Workspace guide](reference-and-help/workspace-guide.md)
+* [Flags & environment](reference-and-help/flags-and-environment.md)
+* [Troubleshooting map](reference-and-help/troubleshooting-map.md)
 * [FAQ](reference-and-help/faq.md)
 * [Contributing & Bug reports](reference-and-help/contributing-and-bug-reports.md)
diff --git a/docs/commands/dcr-build.md b/docs/commands/dcr-build.md
index f0170a3..7e805f5 100644
--- a/docs/commands/dcr-build.md
+++ b/docs/commands/dcr-build.md
@@ -52,9 +52,9 @@ dcr build --debug --clean
 
 ## Notes
 
-- The profile is selected from the first argument only.
+- Profile flag (`--debug` / `--release`) can appear in any argument position (duplicates are rejected).
 - Unknown profile flags return an error.
-- Incremental rebuild is based on source/object mtime comparison.
+- Incremental rebuild checks source/object mtime and tracked header dependencies.
 - `--force` skips build cache checks and recompiles.
 - `--clean` removes `target/<profile>` and `build.clean` paths before building.
 - For `language = "asm"` with `compiler = "as"`/`"gas"`, use `.s` files (no preprocessing). For `.S`, use `gcc` or `clang`.
diff --git a/docs/configuration/dcr.toml-overview.md b/docs/configuration/dcr.toml-overview.md
index 0f6b74b..22f9734 100644
--- a/docs/configuration/dcr.toml-overview.md
+++ b/docs/configuration/dcr.toml-overview.md
@@ -27,7 +27,8 @@ kind = "bin"
 - `[dependencies]`
 
 Workspace-only root:
-- `[workspace]` may be used instead of `[package]`/`[build]` for a workspace root.
+- `[workspace]` can be added to a normal root config to define members and dependency order.
+- Root config still requires `[package]`, `[build]`, and `[dependencies]`.
 
 ## Required keys
 
diff --git a/docs/getting-started/build-and-run.md b/docs/getting-started/build-and-run.md
index 87ec5b1..24c1040 100644
--- a/docs/getting-started/build-and-run.md
+++ b/docs/getting-started/build-and-run.md
@@ -46,7 +46,7 @@ dcr clean --release --all
 ## Notes
 
 - `run` is unavailable for `build.kind = "staticlib"` and `build.kind = "sharedlib"`.
-- Build profile flag is parsed from the first command argument.
+- Build profile flag (`--debug` / `--release`) can be passed in any argument position.
 - Unknown profile flags produce an error.
 - In workspace root, `clean --all` cleans all member projects.
 - `--clean` for `build`/`run` removes `target/<profile>` and paths from `build.clean`.
diff --git a/docs/reference-and-help/cli-reference.md b/docs/reference-and-help/cli-reference.md
index ea93c8c..f625f66 100644
--- a/docs/reference-and-help/cli-reference.md
+++ b/docs/reference-and-help/cli-reference.md
@@ -8,6 +8,7 @@ dcr init
 dcr build [--debug|--release]
 dcr run [--debug|--release]
 dcr clean [--debug|--release] [--all]
+dcr gen <subcommand>
 dcr --help
 dcr --version
 dcr --update
@@ -15,12 +16,13 @@ dcr --update
 
 ## Notes on argument parsing
 
-- Most commands parse profile from the first argument.
+- `build`/`run` parse flags in any order (`--debug|--release`, `--force`, `--clean`) and reject duplicates.
 - `new` requires exactly one argument.
 - `init` and `--update` do not accept extra arguments.
 - `clean` accepts `--debug|--release` and optional `--all`.
+- `gen` supports `project-info`, `compile-commands`, `vscode`, `clion`.
 
 ## Exit behavior overview
 
 - Successful command execution returns `0`.
-- Validation/build/runtime errors return non-zero status.
+- Validation/build/runtime failures return non-zero status.
diff --git a/docs/reference-and-help/faq.md b/docs/reference-and-help/faq.md
index e223667..65a0ab2 100644
--- a/docs/reference-and-help/faq.md
+++ b/docs/reference-and-help/faq.md
@@ -2,7 +2,7 @@
 
 ## What commands are available?
 
-`new`, `init`, `build`, `run`, `clean`, `--help`, `--version`, `--update`.
+`new`, `init`, `build`, `run`, `clean`, `gen`, `--help`, `--version`, `--update`.
 
 ## Is `dcr.toml` mandatory?
 
@@ -21,7 +21,8 @@ Yes. Set `build.compiler` in `dcr.toml` (for example `gcc`, `clang`, `cl`, `clan
 
 ## How does incremental rebuild work?
 
-It compares source file mtime with object file mtime. Header dependency tracking is not implemented yet.
+It compares source file mtime with object file mtime.
+Header dependencies are tracked too: if an included header changes (or disappears), rebuild is triggered.
 
 ## What does `dcr run` do if build fails?
 
diff --git a/docs/reference-and-help/flags-and-environment.md b/docs/reference-and-help/flags-and-environment.md
new file mode 100644
index 0000000..d776410
--- /dev/null
+++ b/docs/reference-and-help/flags-and-environment.md
@@ -0,0 +1,48 @@
+# Flags & environment
+
+This page summarizes runtime flags and environment variables that affect DCR behavior.
+
+## Build/run flags
+
+Used with `dcr build` and `dcr run`:
+
+- `--debug`: select debug profile.
+- `--release`: select release profile.
+- `--force`: ignore incremental cache checks and rebuild.
+- `--clean`: remove `target/<profile>` and `build.clean` paths before build.
+
+Notes:
+
+- Flags can be passed in any order.
+- Duplicate profile flags are rejected.
+
+## Clean flags
+
+Used with `dcr clean`:
+
+- `--debug` / `--release`: clean only selected profile directory.
+- `--all`: in workspace root, also clean all members.
+
+## Environment variables
+
+Tool selection overrides:
+
+- `DCR_COMPILER` (all languages)
+- `DCR_CC`, `DCR_CXX`, `DCR_AS`, `DCR_AR`, `DCR_LD`
+
+Diagnostics:
+
+- `DCR_DEBUG=1` enables verbose build logging.
+
+## Quick examples
+
+```sh
+# Force full release rebuild
+dcr build --release --force
+
+# Clean before debug run
+dcr run --clean --debug
+
+# Use custom compiler from env
+DCR_CC=clang-18 dcr build --debug
+```
diff --git a/docs/reference-and-help/troubleshooting-map.md b/docs/reference-and-help/troubleshooting-map.md
new file mode 100644
index 0000000..c8f9cf9
--- /dev/null
+++ b/docs/reference-and-help/troubleshooting-map.md
@@ -0,0 +1,75 @@
+# Troubleshooting map
+
+Fast mapping from symptom to likely cause and first action.
+
+## `dcr.toml file not found`
+
+Likely cause:
+- you are outside project root (or member root).
+
+First action:
+```sh
+pwd
+ls
+```
+Run DCR from directory that contains `dcr.toml`.
+
+## `Invalid config: missing [package]` / `missing [build]`
+
+Likely cause:
+- incomplete config in root project.
+
+First action:
+- ensure root `dcr.toml` includes `[package]`, `[build]`, and `[dependencies]`.
+- for workspace setups, keep these sections in root and add `[workspace]` additionally.
+
+## `Unknown build flag` or profile-flag errors
+
+Likely cause:
+- typo in flag or duplicate profile flag.
+
+First action:
+```sh
+dcr --help
+```
+Use only supported flags and at most one of `--debug` / `--release`.
+
+## Dependency include/lib path errors
+
+Likely cause:
+- path in `[dependencies]` does not exist.
+
+First action:
+- verify `path`, `include`, `lib` values.
+- if using profile placeholders, confirm expanded paths exist for selected profile.
+
+## `Cannot run library build`
+
+Likely cause:
+- `build.kind` is `staticlib` or `sharedlib`.
+
+First action:
+- switch `build.kind` to `bin`, or set `[run].cmd` if you intentionally need custom run command.
+
+## Build succeeds but output is stale
+
+Likely cause:
+- stale artifacts or generated files from previous runs.
+
+First action:
+```sh
+dcr clean --all
+dcr build --force
+```
+
+## `dcr --update` suggests package manager update
+
+Likely cause:
+- DCR binary is managed by pacman/AUR.
+
+First action:
+```sh
+yay -Syu dcr
+# or
+paru -Syu dcr
+```
diff --git a/docs/reference-and-help/workspace-guide.md b/docs/reference-and-help/workspace-guide.md
new file mode 100644
index 0000000..55f7eae
--- /dev/null
+++ b/docs/reference-and-help/workspace-guide.md
@@ -0,0 +1,53 @@
+# Workspace guide
+
+`[workspace]` lets you build related DCR projects in dependency order from one root.
+
+## Important rule
+
+Workspace root still needs a valid root project config:
+
+- `[package]`
+- `[build]`
+- `[dependencies]`
+
+`[workspace]` augments that root config; it does not replace required root sections.
+
+## Minimal example
+
+```toml
+[package]
+name = "root-app"
+version = "0.1.0"
+
+[build]
+language = "c"
+standard = "c11"
+compiler = "clang"
+kind = "bin"
+
+[dependencies]
+
+[workspace]
+core = { path = "./modules/core", deps = [] }
+net = { path = "./modules/net", deps = ["core"] }
+app = { path = "./modules/app", deps = ["core", "net"] }
+```
+
+Each member path must point to a directory containing its own `dcr.toml`.
+
+## Build behavior
+
+- Running `dcr build` in workspace root builds members in topological dependency order, then builds the root project.
+
+- Running `dcr clean --all` in workspace root cleans all members too.
+
+- `dcr gen` in workspace root includes root + members in generated outputs.
+
+## Common errors
+
+- `workspace.<name>.path does not contain dcr.toml`:
+  member path is wrong or config is missing.
+- `workspace dependency '<name>' not found`:
+  `deps` references unknown member.
+- `workspace dependency cycle at <name>`:
+  cyclic dependencies in member graph.