Codex CLI · coding tool history

2026

of 10

v0.99.0 Apr 23, 2026 major

Major persona and formatting overhaul

Version 0.99.0 introduced a detailed Personality section defining Codex's values (clarity, pragmatism, rigor), interaction style, and escalation behavior. Formatting and presentation rules were reorganized from a single trailing section into structured guidance embedded earlier in the prompt, with several rules tightened or rewritten. A new constraint on non-interactive git commands was also added.

promptsPrompt block / 0: +1,576 chars
promptsPrompt block / 1: -598 chars
transportHeader / user_agent: codex_exec/0.98.0 (Debian 12.0.0; x86_64) vscode/1.115.0 -> codex_exec/0.99.0 (Debian 12.0.0; x86_64) vscode/1.115.0

PromptsTransportpersonaformattingworkflow

Split-view diff4 fields changedprompts · 3transport · 1

Field	Before	After
promptstotal prompt size	8,502 chars	9,480 chars (+978)
promptsblock 0	previous text	text changed (+1,576 chars)
promptsblock 1	previous text	text changed (-598 chars)
transportheader / user_agent	codex_exec/0.98.0 (Debian 12.0.0; x86_64) vscode/1.115.0	codex_exec/0.99.0 (Debian 12.0.0; x86_64) vscode/1.115.0

2026

of 10

v0.106.0 Apr 23, 2026 major

Major persona, workflow, and formatting overhaul

The persona was stripped of its "quiet joy/enthusiasm" framing in favor of purely direct, factual communication, and cheerleading-acknowledgment language was removed entirely. The "Working with the user" section was substantially rewritten to introduce a two-channel model (commentary vs. final), explicit autonomy/persistence directives, detailed intermediary-update cadence rules, and revised file-reference conventions (markdown links instead of inline code). Several sections were removed or restructured, including the plan-tool guidance block, while tool-use gained a new parallel-calls directive and an instruction to avoid Python for simple file I/O.

promptsPrompt block / 0: +3,164 chars
modelModel setting / model: gpt-5.2-codex -> gpt-5.3-codex
transportHeader / user_agent: codex_exec/0.105.0 (Debian 12.0.0; x86_64) vscode/1.115.0 -> codex_exec/0.106.0 (Debian 12.0.0; x86_64) vscode/1.115.0

ModelPromptsTransportpersonaworkflowformatting

Split-view diff4 fields changedprompts · 2model · 1transport · 1

Field	Before	After
promptstotal prompt size	9,480 chars	12,644 chars (+3,164)
promptsblock 0	previous text	text changed (+3,164 chars)
modelmodel	gpt-5.2-codex	gpt-5.3-codex
transportheader / user_agent	codex_exec/0.105.0 (Debian 12.0.0; x86_64) vscode/1.115.0	codex_exec/0.106.0 (Debian 12.0.0; x86_64) vscode/1.115.0

2026

of 10

v0.115.0 Apr 23, 2026 major

Adds skill-discovery and execution system

A new `<skills_instructions>` block introduces a full "Skills" subsystem, pre-loading three built-in skills (openai-docs, skill-creator, skill-installer) and defining detailed rules for triggering, loading, coordinating, and safely falling back on SKILL.md files. This is a significant new capability: the assistant can now discover and follow locally-stored instruction sets on demand, scoped per-turn. Engineers relying on consistent, stateless behavior should review the trigger and context-hygiene rules carefully.

toolsTool added / close_agent: new tool description
schemasSchema added / close_agent: new input schema
toolsTool added / resume_agent: new tool description

PromptsSchemasToolsTransportworkflowtool-usecontext

Split-view diff9 fields changedtools · 6prompts · 2transport · 1

Field	Before	After
toolsclose_agent	—	added
toolsresume_agent	—	added
toolssend_input	—	added
toolsspawn_agent	—	added
toolswait_agent	—	added
toolstool count	7	12
promptstotal prompt size	12,684 chars	16,120 chars (+3,436)
promptsblock 1	previous text	text changed (+3,436 chars)
transportheader / user_agent	codex_exec/0.114.0 (Debian 12.0.0; x86_64) vscode/1.115.0 (codex-exec; 0.114.0)	codex_exec/0.115.0 (Debian 12.0.0; x86_64) vscode/1.115.0 (codex-exec; 0.115.0)

2026

of 10

v0.117.0 Apr 23, 2026 notable

Two new system skills added

Two new built-in skills were registered in the available skills list: `imagegen`, for AI-generated or AI-edited raster/bitmap images, and `plugin-creator`, for scaffolding Codex plugin directories and marketplace metadata. These expand the assistant's out-of-the-box capability surface without changing any existing skills or workflow logic.

toolsTool description / close_agent: description +44 chars
schemasTool schema / close_agent: properties +target / properties -id / required changed
schemasTool schema / send_input: properties +target / properties -id / required changed

PromptsSchemasToolstool-useworkflow

Split-view diff7 fields changedschemas · 3tools · 2prompts · 2

Field	Before	After
toolsclose_agent / description	previous description	description changed (+44 chars)
schemasclose_agent	had: id · required list changed	now has: target · required list changed
schemassend_input	had: id · required list changed	now has: target · required list changed
toolsspawn_agent / description	previous description	description changed (-27 chars)
schemaswait_agent	had: ids · required list changed	now has: targets · required list changed
promptstotal prompt size	16,120 chars	17,261 chars (+1,141)
promptsblock 1	previous text	text changed (+1,141 chars)

2026

of 10

v0.123.0 Apr 23, 2026 major

Major persona, workflow, and formatting overhaul

This version introduces a top-level expert-coding-agent persona statement, promotes `apply_patch` from preferred to mandatory for manual edits, and significantly rewrites the final-answer formatting rules to favor concise prose over bullets and long explanations. The autonomy/persistence section was moved earlier in the document, unexpected-change handling was softened from "stop immediately" to "only stop if it conflicts with your task," and bash command chaining (e.g. `echo "===="`) was explicitly banned. User-update frequency shifted from every 20s to every 30s, and React best-practice guidance was added to the frontend section.

toolsTool description / spawn_agent: description -381 chars
schemasTool schema / spawn_agent: schema changed
promptsPrompt block / 0: +2,389 chars

ModelPromptsSchemasToolspersonaworkflowformatting

Split-view diff6 fields changedprompts · 3tools · 1schemas · 1model · 1

Field	Before	After
toolsspawn_agent / description	previous description	description changed (-381 chars, -1 lines)
schemasspawn_agent	previous schema	updated schema
promptstotal prompt size	17,261 chars	19,650 chars (+2,389)
promptsblock 0	previous text	text changed (+2,389 chars)
promptsblock 1	previous text	text changed (0 chars net)
modelmodel	gpt-5.3-codex	gpt-5.4

2026

of 10

v0.125.0 Apr 29, 2026 major

Adds extensive frontend and engineering-judgment guidance

The update adds two large new sections: a detailed "Engineering judgment" block prescribing conservative, codebase-sympathetic implementation choices, and a comprehensive "Frontend guidance" block covering design empathy, UI component rules, typography, layout, 3D/Three.js, and responsive constraints. The old "Frontend tasks" section (which pushed bold, anti-"AI slop" aesthetics) was removed and replaced by the more structured and prescriptive frontend guidance. Persona, workflow, and intermediary-update instructions were also extensively reworded in a more conversational first-person voice, and several new commentary rules were added (e.g., checklist incremental updates, anti-goblin/creature clause, and ghost-request sanity check on resume).

toolsTool description / spawn_agent: description +369 chars
promptsPrompt block / 0: +6,603 chars
promptsPrompt block / 1: +0 chars

ModelPromptsToolsworkflowpersonaformatting

Split-view diff5 fields changedprompts · 3tools · 1model · 1

Field	Before	After
toolsspawn_agent / description	previous description	description changed (+369 chars, +1 lines)
promptstotal prompt size	19,639 chars	26,242 chars (+6,603)
promptsblock 0	previous text	text changed (+6,603 chars)
promptsblock 1	previous text	text changed (0 chars net)
modelmodel	gpt-5.4	gpt-5.5

2026

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v0.133.0 May 26, 2026 notable

Plugin-creator skill gains update flow

The `plugin-creator` skill description was expanded to include a new use case: updating an existing local plugin during development using a CLI-driven cachebuster and reinstall flow. This broadens the skill's declared scope beyond initial creation and marketplace entry management to cover iterative plugin development.

toolsTool added / create_goal: new tool description
schemasSchema added / create_goal: new input schema
toolsTool added / get_goal: new tool description

PromptsSchemasToolsTransporttool-useworkflow

Split-view diff12 fields changedtools · 9prompts · 2transport · 1

Field	Before	After
toolscreate_goal	—	added
toolsget_goal	—	added
toolsupdate_goal	—	added
toolsclose_agent	present	—
toolsresume_agent	present	—
toolssend_input	present	—
toolsspawn_agent	present	—
toolswait_agent	present	—
toolstool count	12	11
promptstotal prompt size	26,213 chars	26,316 chars (+103)
promptsblock 1	previous text	text changed (+103 chars)
transportheader / user_agent	codex_exec/0.132.0 (Debian 12.0.0; x86_64) vscode/1.121.0 (codex_exec; 0.132.0)	codex_exec/0.133.0 (Debian 12.0.0; x86_64) vscode/1.121.0 (codex_exec; 0.133.0)

2026

of 10

v0.136.0 Jun 3, 2026 notable

openai-docs skill gains Codex self-knowledge

The `openai-docs` skill description was updated to explicitly cover questions about Codex itself and choosing Codex surfaces, and its routing logic was refined to prefer a "Codex manual helper" for broad Codex self-knowledge questions before falling back to general OpenAI docs MCP tools. All other skill entries were unchanged in substance; only the temporary working-directory path segment changed across all entries.

schemasTool schema / create_goal: schema changed
schemasTool schema / exec_command: schema changed
schemasTool schema / update_plan: schema changed

PromptsSchemasTransportworkflowcontextbugfix

Split-view diff8 fields changedschemas · 5prompts · 2transport · 1

Field	Before	After
schemascreate_goal	previous schema	updated schema
schemasexec_command	previous schema	updated schema
schemasupdate_plan	previous schema	updated schema
schemasview_image	previous schema	updated schema
schemaswrite_stdin	previous schema	updated schema
promptstotal prompt size	26,376 chars	26,462 chars (+86)
promptsblock 1	previous text	text changed (+86 chars)
transportheader / user_agent	codex_exec/0.135.0 (Debian 12.0.0; x86_64) vscode/1.122.1 (codex_exec; 0.135.0)	codex_exec/0.136.0 (Debian 12.0.0; x86_64) vscode/1.122.1 (codex_exec; 0.136.0)

2026

of 10

v0.140.0 Jun 16, 2026 major

Skills system gains multi-locator support

The skills framework was expanded beyond filesystem-only `SKILL.md` paths to support multiple resource locator types: `file`, `environment resource`, `orchestrator resource`, and `custom resource`. Reading instructions were substantially rewritten to handle each locator type distinctly, including using `skills.list`/`skills.read` for orchestrator-backed skills and explicit rules against treating `skill://` URIs as filesystem paths. Temporary file paths in skill entries were also scrubbed to a generic `<scrub>` placeholder, and the context-hygiene rule was clarified to distinguish progressive disclosure of files from partial reading of a selected instruction file.

toolsTool description / create_goal: description +12 chars
schemasTool schema / create_goal: schema changed
toolsTool description / request_user_input: description +230 chars

PromptsSchemasToolsTransporttool-useworkflowenvironment

Split-view diff7 fields changedtools · 2schemas · 2prompts · 2transport · 1

Field	Before	After
toolscreate_goal / description	previous description	description changed (+12 chars)
schemascreate_goal	previous schema	updated schema
toolsrequest_user_input / description	previous description	description changed (+230 chars)
schemasrequest_user_input	previous schema	now has: autoResolutionMs
promptstotal prompt size	26,462 chars	27,781 chars (+1,319)
promptsblock 1	previous text	text changed (+1,319 chars)
transportheader / user_agent	codex_exec/0.137.0 (Debian 12.0.0; x86_64) vscode/1.123.0 (codex_exec; 0.137.0)	codex_exec/0.140.0 (Debian 12.0.0; x86_64) vscode/1.124.2 (codex_exec; 0.140.0)

2026

of 10

v0.144.0 Jul 15, 2026 major

Major persona and workflow overhaul

The persona was substantially rewritten from a terse, pragmatic senior-engineer voice to a warmer, curiosity-driven communicator that adapts to user tone. Large swaths of frontend design rules, engineering judgment guidelines, and git/editing constraints were condensed or removed, replaced with a cleaner autonomy model and more explicit commentary/final-channel guidance. Skill-use instructions were restructured with alias resolution, clearer trigger rules, and new transparency requirements around skill announcements.

toolsTool removed / apply_patch: tool removed
schemasSchema removed / apply_patch: input schema removed
toolsTool removed / create_goal: tool removed

ModelPromptsSchemasToolsTransportpersonaworkflowtool-use

Split-view diff16 fields changedtools · 10prompts · 3model · 2transport · 1

Field	Before	After
toolsapply_patch	present	—
toolscreate_goal	present	—
toolsexec_command	present	—
toolsget_goal	present	—
toolsrequest_user_input	present	—
toolsupdate_goal	present	—
toolsupdate_plan	present	—
toolsview_image	present	—
toolswrite_stdin	present	—
toolstool count	11	0
promptstotal prompt size	27,781 chars	16,299 chars (-11,482)
promptsblock 0	previous text	text changed (-5,036 chars)
promptsblock 1	prompt block present	—
modelmodel	gpt-5.5	gpt-5.6-sol
modelthinking	{"effort": "medium"}	{"context": "all_turns", "effort": "low"}
transportheader / user_agent	codex_exec/0.143.0 (Debian 12.0.0; x86_64) vscode/1.128.1 (codex_exec; 0.143.0)	codex_exec/0.144.0 (Debian 12.0.0; x86_64) vscode/1.128.1 (codex_exec; 0.144.0)