diff --git a/work-items/open/20260531-003743-codex-gpt55-effective-context-window/artifacts/.gitkeep b/work-items/closed/20260531-003743-codex-gpt55-effective-context-window/artifacts/.gitkeep
similarity index 100%
rename from work-items/open/20260531-003743-codex-gpt55-effective-context-window/artifacts/.gitkeep
rename to work-items/closed/20260531-003743-codex-gpt55-effective-context-window/artifacts/.gitkeep
diff --git a/work-items/open/20260531-003743-codex-gpt55-effective-context-window/item.md b/work-items/closed/20260531-003743-codex-gpt55-effective-context-window/item.md
similarity index 98%
rename from work-items/open/20260531-003743-codex-gpt55-effective-context-window/item.md
rename to work-items/closed/20260531-003743-codex-gpt55-effective-context-window/item.md
index b65eb3a3..0c3f340e 100644
--- a/work-items/open/20260531-003743-codex-gpt55-effective-context-window/item.md
+++ b/work-items/closed/20260531-003743-codex-gpt55-effective-context-window/item.md
@@ -2,12 +2,12 @@
 id: 20260531-003743-codex-gpt55-effective-context-window
 slug: codex-gpt55-effective-context-window
 title: Provider: make codex gpt-5.5 context window effective
-status: open
+status: closed
 kind: task
 priority: P2
 labels: [provider, models, catalog]
 created_at: 2026-05-31T00:37:43Z
-updated_at: 2026-05-31T01:57:38Z
+updated_at: 2026-05-31T01:58:24Z
 assignee: null
 legacy_ticket: null
 ---
diff --git a/work-items/closed/20260531-003743-codex-gpt55-effective-context-window/resolution.md b/work-items/closed/20260531-003743-codex-gpt55-effective-context-window/resolution.md
new file mode 100644
index 00000000..ef6f8c62
--- /dev/null
+++ b/work-items/closed/20260531-003743-codex-gpt55-effective-context-window/resolution.md
@@ -0,0 +1 @@
+Updated the builtin `codex-oauth/gpt-5.5` entry so `context_window = 272000` directly represents the effective Codex OAuth / ChatGPT backend route limit, with a catalog comment explaining that generic OpenAI docs advertise 1.05M. Removed catalog-level `max_context_window` from that entry while preserving inline/config `max_context_window` support. External review approved and validation passed.
diff --git a/work-items/open/20260531-003743-codex-gpt55-effective-context-window/thread.md b/work-items/closed/20260531-003743-codex-gpt55-effective-context-window/thread.md
similarity index 73%
rename from work-items/open/20260531-003743-codex-gpt55-effective-context-window/thread.md
rename to work-items/closed/20260531-003743-codex-gpt55-effective-context-window/thread.md
index 9568531d..74aa46a8 100644
--- a/work-items/open/20260531-003743-codex-gpt55-effective-context-window/thread.md
+++ b/work-items/closed/20260531-003743-codex-gpt55-effective-context-window/thread.md
@@ -64,4 +64,31 @@ Reviewer summary:
 Blockers: none.
 
 
+---
+
+<!-- event: implementation_report author: hare at: 2026-05-31T01:58:24Z -->
+
+## Implementation report
+
+Main workspace validation after merge:
+
+- `cargo fmt --check` passed
+- `cargo test -p provider catalog` passed
+- `cargo test -p manifest model` passed
+- `cargo check -p provider -p manifest` passed
+- `./tickets.sh doctor` passed
+- `git diff --check` passed
+
+Warnings observed are pre-existing dead-code warnings in `llm-worker` / filtered manifest test helpers.
+
+
+---
+
+<!-- event: close author: hare at: 2026-05-31T01:58:24Z status: closed -->
+
+## Closed
+
+Updated the builtin `codex-oauth/gpt-5.5` entry so `context_window = 272000` directly represents the effective Codex OAuth / ChatGPT backend route limit, with a catalog comment explaining that generic OpenAI docs advertise 1.05M. Removed catalog-level `max_context_window` from that entry while preserving inline/config `max_context_window` support. External review approved and validation passed.
+
+
 ---