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The GPT Project Skill System is a session-scoped skill loader with an explicit and narrow contract. This page documents what the system deliberately does not provide, defines the strict boundary of session scope, distinguishes hard fail from degraded load, and explains what activation and mounting actually mean at runtime.

What the system does not provide

The following capabilities are outside the scope of the runtime by design. None of them exist at any layer of the system:
FeatureStatus
HooksNot provided
Watcher behaviorNot provided
Persistent runtime stateNot provided
Automatic routingNot provided
Install into the modelNot provided
Marketplace behaviorNot provided
Internet auto-installNot provided
Permanent skill installationNot provided
Automatic skill discoveryNot provided
Automatic skill loadingNot provided
DaemonsNot provided
Dependency installationNot provided
No file, manifest field, or metadata claim inside a skill or core package can override these limits. A runtime_hints object stating "uses_python": true does not install Python packages. A capabilities array does not create routing or authorization. These fields are descriptive metadata only.

Session scope

The active semantic set exists only in the current chat session.
  • Nothing persists across chats.
  • Nothing persists across sessions.
  • A skill that was loaded in a previous chat is not active in the current chat unless explicitly reloaded.
To reactivate skills in a new chat, run SKILL CORE UNPACK followed by the relevant SKILL <name> LOAD commands. The physical install on disk persists between chats (within Project storage), but semantic activation does not.
When the work focus changes materially, close the active session by opening a new chat and repeating a targeted boot/load cycle. This keeps the active semantic set small and prevents context drift.

What activation means

After SKILL CORE UNPACK completes successfully, the core is activated for the session. After SKILL <name> LOAD completes successfully, the skill is activated for the session. Activation means:
  • The files declared in MANIFEST.json have been read in manifest order.
  • Required files passed mechanical validation (presence, UTF-8 readability, path policy).
  • Optional files, if declared, have either mounted successfully or produced degraded load warnings.
  • The model treats the mounted files as the active semantic perimeter for the current session.
Activation does NOT mean:
  • Installation into the model
  • Hook execution
  • Runtime binding
  • Watcher behavior
  • Persistent enforcement across sessions
  • Routing outside the current session
  • Serialized runtime state

What mount means

load_sequence is the only automatic semantic mount list. Files outside load_sequence — including support_files, tool_files, and asset_files — are physically available on disk after unpack but are not mounted automatically. Mount means:
Validated reading of AI-only files declared by a manifest and semantic insertion into the current session context.
Mount does NOT mean:
  • Installation into the model
  • Runtime binding
  • Persistent enforcement
  • Automatic routing
  • Watcher behavior
  • Serialized state
A skill folder present under /mnt/data/GPT.SKILLS/SKILLS/ means the skill is installed physically. It does not mean the skill is semantically active. Only SKILL <name> LOAD makes an installed skill active.

Tool file limits

Files listed in tool_files are subject to the following restrictions:
  • Never mounted automatically — they do not become part of the session context.
  • Never run automatically — the Python environment may execute them only when explicitly invoked.
  • May use only the Python standard library or packages already available in the current GPT Python environment.
  • No pip install is permitted.
  • No network install is permitted.
If a required dependency is missing at execution time, tool execution degrades or fails with a warning. It does not hard fail the load of the skill itself. Skills should provide a non-script fallback whenever possible.

Hard fail vs degraded load

The runtime distinguishes between two failure modes.

Hard fail

A hard fail stops the operation immediately with no partial state. The following conditions always cause hard fail:
  • MANIFEST.json is missing
  • MANIFEST.json is not valid JSON
  • The manifest is invalid (any invalidity condition listed in the manifest schema)
  • primary_file is missing from the extracted tree
  • Any required file in load_sequence is missing from the extracted tree
  • Any required file in load_sequence is not readable as UTF-8
  • Any required path resolves to a directory instead of a file
  • Any present optional path resolves to a directory instead of a file

Degraded load

Degraded load is allowed only for files in optional_load_sequence, and only after the manifest itself has been validated successfully. Degraded load applies when:
  • An optional file is missing from the extracted tree.
  • An optional file is present but not readable as UTF-8.
Degraded load behavior:
  1. Continue with the load — do not abort.
  2. Do not mount the affected optional file.
  3. Emit a concise technical warning identifying the file.
  4. Do not represent the optional file as active in the session.
Degradation never applies to MANIFEST.json, primary_file, any file in load_sequence, any invalid manifest path, or any directory target. These are always hard fail conditions.

Mechanical validation vs semantic review

The runtime enforces two distinct layers of correctness checking.

Mechanical validation (Python hard checks)

Mechanical validation is enforced by the Python runtime and covers:
  • Parsing manifest JSON
  • Validating field types and required field presence
  • Validating system_name and version (core)
  • Detecting duplicate entries inside each load list
  • Detecting overlap between required and optional lists
  • Enforcing path policy (absolute paths, .., subdirectory restrictions, extensions)
  • Confirming required file presence in the extracted tree
  • Confirming UTF-8 readability of required files
  • Probing UTF-8 readability of optional files (with degradable outcome)
  • Enforcing mounted file extension restrictions (core)
  • Distinguishing file targets from directory targets

Semantic review (external, not a hard check)

Semantic review is external to the runtime core and is not reliable Python hard validation. It checks:
  • File role separation (e.g., lifecycle rules must not appear in SEMANTICS.md)
  • No operational rules inside README.md
  • No hook, binding, watcher, routing, or persistent enforcement claims in any core file
  • No global core rules inside skill packages
  • No alternate mount order declared outside MANIFEST.json
  • No contradiction between core files and manifest order
The following are semantic invalidities, not mechanical hard fails: a core file declaring an alternate mount order, README.md containing operational rules, SEMANTICS.md containing lifecycle commands, or a core file claiming hook or watcher behavior. The Python runtime will not catch these — they require external review.

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