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diff --git a/docs/dev/style.md b/docs/dev/style.md
index 389649398..428cee3ad 100644
--- a/docs/dev/style.md
+++ b/docs/dev/style.md
@@ -6,6 +6,9 @@ Our approach to "clean code" is two-fold:
 It is explicitly OK for a reviewer to flag only some nits in the PR, and then send a follow-up cleanup PR for things which are easier to explain by example, cc-ing the original author.
 Sending small cleanup PRs (like renaming a single local variable) is encouraged.
 
+When reviewing pull requests prefer extending this document to leaving
+non-reusable comments on the pull request itself.
+
 # General
 
 ## Scale of Changes
@@ -139,6 +142,17 @@ There are many benefits to this:
 
 Formatting ensures that you can use your editor's "number of selected characters" feature to correlate offsets with test's source code.
 
+## Marked Tests
+
+Use
+[`mark::hit! / mark::check!`](https://github.com/rust-analyzer/rust-analyzer/blob/71fe719dd5247ed8615641d9303d7ca1aa201c2f/crates/test_utils/src/mark.rs)
+when testing specific conditions.
+Do not place several marks into a single test or condition.
+Do not reuse marks between several tests.
+
+**Rationale:** marks provide an easy way to find the canonical test for each bit of code.
+This makes it much easier to understand.
+
 ## Function Preconditions
 
 Express function preconditions in types and force the caller to provide them (rather than checking in callee):
@@ -375,6 +389,14 @@ This allows for exceptionally good performance, but leads to increased compile t
 Runtime performance obeys 80%/20% rule -- only a small fraction of code is hot.
 Compile time **does not** obey this rule -- all code has to be compiled.
 
+## Appropriate String Types
+
+When interfacing with OS APIs, use `OsString`, even if the original source of data is utf-8 encoded.
+**Rationale:** cleanly delineates the boundary when the data goes into the OS-land.
+
+Use `AbsPathBuf` and `AbsPath` over `std::Path`.
+**Rationale:** rust-analyzer is a long-lived process which handles several projects at the same time.
+It is important not to leak cwd by accident.
 
 # Premature Pessimization