diff --git a/.github/workflows/lint_sqlfluff.yml b/.github/workflows/lint_sqlfluff.yml
index 0986785b..d6e1c3f0 100644
--- a/.github/workflows/lint_sqlfluff.yml
+++ b/.github/workflows/lint_sqlfluff.yml
@@ -1,11 +1,17 @@
 name: SQLFluff
 
+# Lints changed mimic-iv/concepts/*.sql on pull requests and posts GitHub
+# annotations. Fork PRs skip Annotate — GITHUB_TOKEN cannot create check runs
+# from forks (Resource not accessible by integration / 403).
 on:
   - pull_request
 
 jobs:
   lint-mimic-iv:
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      checks: write
     steps:
       - name: checkout
         uses: actions/checkout@v7
@@ -35,8 +41,14 @@ jobs:
         shell: bash
         run: sqlfluff lint --format github-annotation --annotation-level failure --nofail ${{ steps.get_files_to_lint.outputs.lintees }} > annotations.json
       - name: Annotate
+        # Same-repo PRs only: fork tokens get 403 creating check runs, and
+        # ignore-unauthorized-error does not treat that as unauthorized.
+        if: >
+          steps.get_files_to_lint.outputs.lintees != '' &&
+          github.event.pull_request.head.repo.full_name == github.repository
         uses: yuzutech/annotations-action@v0.6.0
         with:
           repo-token: "${{ secrets.GITHUB_TOKEN }}"
           title: "SQLFluff Lint"
-          input: "./annotations.json"
\ No newline at end of file
+          input: "./annotations.json"
+          ignore-unauthorized-error: true
diff --git a/README.md b/README.md
index 53fe9f9f..649df76c 100644
--- a/README.md
+++ b/README.md
@@ -114,3 +114,7 @@ By committing your code to the [MIMIC Code Repository](https://github.com/mit-lc
 ### Coding style
 
 Please refer to the [style guide](https://github.com/MIT-LCP/mimic-code/blob/main/styleguide.md) for guidelines on formatting your code for the repository.
+
+### MIMIC-IV timing notes
+
+- [ICU chartevents timing](mimic-iv/docs/CHARTEVENTS_TIMING.md)
diff --git a/mimic-iv/README.md b/mimic-iv/README.md
index 919b196c..28a6b7a9 100644
--- a/mimic-iv/README.md
+++ b/mimic-iv/README.md
@@ -105,4 +105,8 @@ mimic_utils convert_folder mimic-iv/concepts mimic-iv/concepts_duckdb --destinat
 
 # To PostgreSQL:
 mimic_utils convert_folder mimic-iv/concepts mimic-iv/concepts_postgres --destination_dialect postgres
-```
\ No newline at end of file
+```
+
+## Timing caveats
+
+`chartevents.charttime` can legitimately fall outside `icustays` windows — see [docs/CHARTEVENTS_TIMING.md](docs/CHARTEVENTS_TIMING.md).
diff --git a/mimic-iv/concepts/documentation/README.md b/mimic-iv/concepts/documentation/README.md
new file mode 100644
index 00000000..15576507
--- /dev/null
+++ b/mimic-iv/concepts/documentation/README.md
@@ -0,0 +1,4 @@
+# Documentation helper queries
+
+Ad-hoc SQL that illustrates known data quirks. These are **not** part of the
+official derived concept build — run them against a local or BigQuery copy.
diff --git a/mimic-iv/concepts/documentation/chartevents_after_outtime.sql b/mimic-iv/concepts/documentation/chartevents_after_outtime.sql
new file mode 100644
index 00000000..59d90a7b
--- /dev/null
+++ b/mimic-iv/concepts/documentation/chartevents_after_outtime.sql
@@ -0,0 +1,13 @@
+-- Count chartevents whose charttime falls after the linked ICU stay outtime.
+-- Useful as a sensitivity check when building in-ICU only cohorts (#1961).
+
+SELECT
+  COUNT(*) AS chartevents_rows,
+  COUNT(*) FILTER (WHERE ce.charttime > ie.outtime) AS after_outtime,
+  COUNT(*) FILTER (
+    WHERE ce.charttime > ie.outtime
+      AND ce.charttime <= ie.outtime + INTERVAL '6 hours'
+  ) AS after_outtime_within_6h
+FROM icu.chartevents AS ce
+INNER JOIN icu.icustays AS ie
+  ON ce.stay_id = ie.stay_id;
diff --git a/mimic-iv/concepts/documentation/chartevents_before_intime.sql b/mimic-iv/concepts/documentation/chartevents_before_intime.sql
new file mode 100644
index 00000000..728d536f
--- /dev/null
+++ b/mimic-iv/concepts/documentation/chartevents_before_intime.sql
@@ -0,0 +1,12 @@
+-- Count chartevents charted before ICU intime (less common than after outtime).
+
+SELECT
+  COUNT(*) AS before_intime,
+  COUNT(*) FILTER (
+    WHERE ce.charttime < ie.intime
+      AND ce.charttime >= ie.intime - INTERVAL '2 hours'
+  ) AS before_intime_within_2h
+FROM icu.chartevents AS ce
+INNER JOIN icu.icustays AS ie
+  ON ce.stay_id = ie.stay_id
+WHERE ce.charttime < ie.intime;
diff --git a/mimic-iv/docs/CHARTEVENTS_TIMING.md b/mimic-iv/docs/CHARTEVENTS_TIMING.md
new file mode 100644
index 00000000..df993020
--- /dev/null
+++ b/mimic-iv/docs/CHARTEVENTS_TIMING.md
@@ -0,0 +1,46 @@
+# Chartevents timing vs ICU stay windows
+
+Researchers often find `icu.chartevents.charttime` values **after**
+`icu.icustays.outtime` (or occasionally before `intime`). Large absolute counts
+are expected in the raw PhysioNet files and usually do **not** mean a broken
+`stay_id` join.
+
+See [issue #1961](https://github.com/MIT-LCP/mimic-code/issues/1961).
+
+## Why charttime can fall outside `[intime, outtime]`
+
+1. **Late charting.** Nurses and devices often document observations after the
+   patient has left the ICU; the row still carries the ICU `stay_id`.
+2. **Device / interface clocks.** Bedside monitors and EHR interfaces may stamp
+   times that disagree slightly with ADT `intime`/`outtime`.
+3. **Derived stay boundaries.** `icustays` windows are constructed from
+   transfer / careunit logic; charted data is not clipped to those windows in
+   the ETL that loads the CSV files.
+
+The public tables do not expose a "manual vs automatic" provenance flag for
+each `charttime`.
+
+## Practical guidance
+
+- Treat `icustays.intime` / `outtime` as the **administrative** ICU window.
+- For "in-ICU only" cohorts, filter explicitly, e.g.
+  `charttime >= intime AND charttime <= outtime`, and report how many rows you
+  dropped.
+- Prefer a sensitivity analysis that also keeps a short post-`outtime` grace
+  period (e.g. 1–6 hours) when studying labs or vitals that are often charted
+  late.
+- Do **not** rewrite `outtime` from the latest `charttime` inside the PhysioNet
+  loaders — that belongs in a documented derived concept if you need it.
+
+## Related notes
+
+- ED module: `mimic-iv-ed/docs/TIMING_NOTES.md` (`edstays.intime` vs pyxis)
+- Lab / OMR unit caveats: `mimic-iv/buildmimic/TABLE_NOTES.md` when present
+
+## What this repository will not change
+
+MIMIC-Code does **not** clip `chartevents` to `icustays` windows in the
+PhysioNet loaders, and it will not silently rewrite `outtime` from the latest
+charted observation. Clipping belongs in analysis code or an explicitly
+documented derived concept.
+