docs: record v3-exceptions and the final session tags

docs/git-branches-tags.md

@@ -1,9 +1,9 @@
 # Git branches and tags — how this repository is organised
 
-**Snapshot:** 2026-10-23, after `v3-packedset`. `master` =
-`6b2df4c` (the PACKEDSET feature commit) plus a docs follow-up;
-`origin/master` = `2d1c658`.  The new commits are local and **not
-pushed yet**.  300 tags (mostly historical `v3-*` checkpoints).
+**Snapshot:** 2026-10-23, after `v3-exceptions`. `master` =
+`96a3080` (the exceptions M5 docs commit) plus this map update;
+`origin/master` = `2a30d8c`.  The exceptions M1–M5 commits are local
+and **not pushed yet**.  304 tags (302 `v3-*` checkpoints).
 
 Mental model:
 
@@ -14,7 +14,7 @@ Mental model:
 
 | Branch | State | What it is |
 | --- | --- | --- |
-| **`master`** | `6b2df4c` + docs, ahead of origin | The only active branch; all current work is here. |
+| **`master`** | `96a3080` + map, 5 commits ahead of origin | The only active branch; all current work is here. |
 | `ast-stage-c` | `0f611c0` (2026-10-08), local only | Old stage branch, fully merged into master. Stale. |
 | `generics-inc1` | `6639c19`, 6 commits behind `origin/generics-inc1` | Old generics work, fully merged into master. Stale. |
 | `resolve-check` | `95ca4d6`, in sync with origin | Old branch merged into master. Stale. |
@@ -44,6 +44,7 @@ Each points at the commit that landed a feature, all with green gates:
 | `v3-smallfix` | `87e8605` | small conformance items (+6) |
 | `v3-rangechecks` | `54d84b9` | runtime subrange range checks (+3 trap tests) |
 | `v3-packedset` | `6b2df4c` | ISO `PACKEDSET`, 1/2/4-byte storage |
+| `v3-exceptions` | `02b3763` | ISO exceptions M1–M4: parser, runtime, libraries, traps |
 
 These are immutable checkpoints.  Useful commands:
 
@@ -58,7 +59,8 @@ git diff v3-sysclock v3-smallfix      # what the last step changed
 | --- | --- | --- |
 | `v3-session-2026-10-19` | `c9c1121` | Previous session's final summary. |
 | `v3-session-2026-10-23` | `2d1c658` | **Moving** session tag, advanced once for the range-check summary. |
-| `v3-session-2026-10-23-end` | final docs commit | **Final immutable 2026-10-23 tag** (PACKEDSET + docs). |
+| `v3-session-2026-10-23-end` | `adba8eb` | Immutable PACKEDSET/range-check stop point (earlier the same day). |
+| `v3-session-2026-10-23-exceptions-end` | `96a3080` | **Final immutable 2026-10-23 exceptions session tag.** |
 | `v3-session-2026-10-22` | `c2664ac` | **Moving** session tag. Advanced several times and force-pushed to the final commit. |
 | `v3-session-2026-10-22-final` | `0e81019` | **Early checkpoint** created before the session continued (byte/word16/SysClock/smallfix came after). Historical noise now. |
 | `v3-session-2026-10-22-end` | `c2664ac` | **Final immutable session tag.** Use this one. |
@@ -84,18 +86,20 @@ git tag -d v3-session-2026-10-22-final
 git push origin :refs/tags/v3-session-2026-10-22-final
 ```
 
-## Why 300 tags?
+## Why 304 tags?
 
 The project convention is one `v3-*` tag per green step across all
 sessions (two-phase parse slices, generics increments, Unicode, stdlib,
 …).  They are a searchable history of passing states, not branches.
-`git tag --list | wc -l` = 300 is expected; only the recent ones above
-matter for the current session.
+`git tag --list | wc -l` = 304 (302 `v3-*`) is expected; only the
+recent ones above matter for the current session.
 
 ## Current state
 
-- `master` = `6b2df4c` + docs, **ahead** of `origin/master` (`2d1c658`).
-- `v3-rangechecks`, `v3-packedset` and the 2026-10-23 session tags are
-  local; push them with `master` when ready.
+- `master` = `96a3080` + this map, **5 commits ahead** of
+  `origin/master` (`2a30d8c`).
+- `v3-exceptions` and `v3-session-2026-10-23-exceptions-end` are local;
+  push them with `master` when ready.  Earlier PACKEDSET/history tags
+  are already on the remote.
 - Next session: start from `master` and read
   `docs/handoff-2026-10-23-next.md`.