diff --git a/work-items/open/20260531-003743-codex-gpt55-effective-context-window/item.md b/work-items/open/20260531-003743-codex-gpt55-effective-context-window/item.md
index 50f2b066..b65eb3a3 100644
--- a/work-items/open/20260531-003743-codex-gpt55-effective-context-window/item.md
+++ b/work-items/open/20260531-003743-codex-gpt55-effective-context-window/item.md
@@ -7,7 +7,7 @@ kind: task
 priority: P2
 labels: [provider, models, catalog]
 created_at: 2026-05-31T00:37:43Z
-updated_at: 2026-05-31T00:38:23Z
+updated_at: 2026-05-31T01:57:38Z
 assignee: null
 legacy_ticket: null
 ---
diff --git a/work-items/open/20260531-003743-codex-gpt55-effective-context-window/thread.md b/work-items/open/20260531-003743-codex-gpt55-effective-context-window/thread.md
index 04e8e70e..9568531d 100644
--- a/work-items/open/20260531-003743-codex-gpt55-effective-context-window/thread.md
+++ b/work-items/open/20260531-003743-codex-gpt55-effective-context-window/thread.md
@@ -18,4 +18,50 @@ Implementation plan:
 4. Validate with focused provider/manifest tests plus `cargo fmt --check`, `./tickets.sh doctor`, and `git diff --check`.
 
 
+---
+
+<!-- event: implementation_report author: hare at: 2026-05-31T01:57:37Z -->
+
+## Implementation report
+
+Implementation report from coder Pod `codex-gpt55-context-coder-20260531`:
+
+- Branch: `codex-gpt55-effective-context-window`
+- Commit: `ed3e97c22a8e21dce9223114526932a11b268589` (`provider: use codex gpt55 effective context`)
+- Updated `resources/models/builtin.toml` so `codex-oauth/gpt-5.5` records the effective Codex OAuth route limit directly as `context_window = 272000` and no longer has `max_context_window`.
+- Added a nearby comment explaining that OpenAI documents GPT-5.5 as 1.05M context, but Codex OAuth / ChatGPT backend access is effectively limited around 272k.
+- Kept default profile unchanged and did not change OpenRouter `openai/gpt-5.5`.
+- Preserved `max_context_window` support for inline/config overrides and updated tests accordingly.
+
+Validation reported by coder:
+
+- `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
+
+Unresolved issues: none.
+
+
+---
+
+<!-- event: review author: hare at: 2026-05-31T01:57:38Z status: approve -->
+
+## Review: approve
+
+External review by reviewer Pod `codex-gpt55-context-reviewer-20260531`: approve.
+
+Reviewer summary:
+
+- The change is correctly scoped to `codex-oauth/gpt-5.5` and relevant tests.
+- `context_window = 272000` now represents the effective Codex OAuth route limit directly.
+- The comment explains the distinction between OpenAI's advertised 1.05M context window and the observed/known Codex OAuth effective limit.
+- `max_context_window` support remains available for inline/config cases.
+- Default profile and OpenRouter `openai/gpt-5.5` were not changed.
+
+Blockers: none.
+
+
 ---