fix(delegate): block skills tools from leaf subagents to reduce prompt bloat

[kshitijk4poor]

Summary

Leaf subagents no longer receive the skills toolset, eliminating ~2,800 tokens of skill-index bloat from the child's system prompt that caused context-overflow failures on models with smaller effective context windows.

Root cause: subagents inherited the parent's skills tools (skills_list, skill_view, skill_manage), which triggered the full skill index injection in system_prompt.py. On models like qwen3-coder-next with a lower effective context than configured, the API rejected the payload before the first call (#42809).

Changes

• tools/delegate_tool.py: Add skills_list, skill_view, skill_manage to DELEGATE_BLOCKED_TOOLS. The derived _strip_blocked_tools() filter auto-strips the skills toolset (all its tools are now blocked), and _blocked_toolsets_for_role() subtracts them from mixed platform bundles. system_prompt.py's existing has_skills_tools gate already prevents the skill index from being injected when the tools are absent — no prompt changes needed.
• tests/tools/test_delegate.py: 3 regression tests — strip test, constant assertion, _blocked_toolsets_for_role assertion.
• contributors/emails/: Morad37 attribution.

Design decisions

• Dropped the TASK_COMPLETION_GUIDANCE gate from the original PR. The sweeper correctly flagged that this block is a deliberately universal anti-stub/anti-fabrication directive (commit a4d8f0f), not subagent-specific bloat.
• Reworked the delegate_tool.py hunk to use the derived filter from feat(delegate): remove model-facing toolsets arg — subagents inherit parent's #56386 instead of the PR's stale hardcoded list.
• code_execution remains unblocked per Teknium's Jul 2026 decision (feat(delegation): let subagents use execute_code #69325).

Validation

	Before	After
Skills toolset in child	Present (~2,800 tokens)	Stripped
Skills index in child prompt	Injected	Not injected
Test suite	60 pass	63 pass
E2E (_strip_blocked_tools, _blocked_toolsets_for_role)	—	Pass
Ruff	—	Clean

Cherry-picked from #42822 by @Morad37. Closes #42809.

[alt-glitch]

This was generated by AI during triage.

Duplicate of #42822: both remove the skills toolset/index from leaf subagents to address #42809. #42822 is the broader open implementation.

[GottZ]

This was generated by AI during triage.

Summary

Four PRs address #42809. #42823 and #42831 contain the same narrow, now-stale toolset-name filter; #42822 adds broader prompt-guidance removal; and #76081 salvages the root-cause fix against the current derived filtering architecture with regression coverage while retaining universal task-completion guidance.

Related pull requests

• fix(delegate): reduce subagent system prompt bloat #42822 [closed] duplicate — (+11/-7) — superseded by fix(delegate): block skills tools from leaf subagents to reduce prompt bloat #76081: The diff blocks the skills toolset and additionally removes task-completion and per-tool guidance from every subagent, but its filter targets the obsolete blocked_toolset_names implementation and drops deliberately universal anti-stub guidance. Despite the maintainer-bot keep_open verdict on fix(delegate): reduce subagent system prompt bloat #42822, its requested salvage—reworking the fix against DELEGATE_BLOCKED_TOOLS, retaining task-completion guidance, and adding tests—is implemented by fix(delegate): block skills tools from leaf subagents to reduce prompt bloat #76081, which is why this closed PR remains relevant as the broader original proposal.
• fix(delegate): strip skills toolset from leaf subagents #42823 [closed] fixes — (+6/-4) — duplicate, superseded by fix(delegate): block skills tools from leaf subagents to reduce prompt bloat #76081: Its diff adds skills directly to the old _strip_blocked_tools() name set and updates two tests, addressing the skill-index trigger but not the current derived per-tool filtering architecture. It remains relevant as an exact implementation twin of fix(delegate): strip skills toolset from leaf subagents #42831 and an earlier version of the root-cause fix.
• fix(delegate): strip skills toolset from leaf subagents #42831 [closed] best fix — (+6/-4) — duplicate, superseded by fix(delegate): block skills tools from leaf subagents to reduce prompt bloat #76081: Its diff is identical to fix(delegate): strip skills toolset from leaf subagents #42823 and was closed in favor of the broader fix(delegate): reduce subagent system prompt bloat #42822; the same narrow skills-stripping behavior is now carried forward by fix(delegate): block skills tools from leaf subagents to reduce prompt bloat #76081 using the current architecture. It remains relevant as the original narrow fix referenced by the later proposals.
• fix(delegate): block skills tools from leaf subagents to reduce prompt bloat #76081 best fix — (+34/-0) — keep open with a salvage path: The diff blocks skills_list, skill_view, and skill_manage through DELEGATE_BLOCKED_TOOLS, allowing the derived filters to remove the skills toolset and prevent skill-index injection, with regression tests for both direct and role-derived filtering. The contributor's duplicate-of-fix(delegate): reduce subagent system prompt bloat #42822 comment does not reflect the final relationship: fix(delegate): reduce subagent system prompt bloat #42822 is closed, while fix(delegate): block skills tools from leaf subagents to reduce prompt bloat #76081 implements the maintainer-bot's requested current-architecture salvage and intentionally excludes fix(delegate): reduce subagent system prompt bloat #42822's disputed task-completion-guidance removal.

Duplicates

#42823 and #42831 are exact duplicates. Their narrow behavior also overlaps with the skills-stripping portion of #42822 and is superseded by the current-architecture implementation in #76081.

Suggested consolidation

Keep #76081 open with a salvage path: preserve its per-tool DELEGATE_BLOCKED_TOOLS change and regression tests, and keep the universal task-completion guidance unchanged. Despite the maintainer-bot keep_open verdict on #42822, #76081 contains the concrete rework that verdict requested, while #42822's stale filter and broader guidance removal should not be revived; #42822, #42823, and #42831 can remain closed as superseded duplicates.

Complex graph

flowchart LR
    classDef open fill:#dbeafe,stroke:#1d4ed8,color:#1e3a8a
    classDef merged fill:#dcfce7,stroke:#15803d,color:#14532d
    classDef closed fill:#e5e7eb,stroke:#6b7280,color:#1f2937
    classDef unverified fill:#f3f4f6,stroke:#9ca3af,color:#374151
    classDef best stroke-width:3px,stroke:#b45309
    classDef target stroke-width:3px,stroke:#4338ca
    I42809(["issue #42809 (open)"])
    subgraph Dup42822 ["PRs duplicating each other"]
        P42822["PR #42822 (closed)"]
        P42823["PR #42823 (closed)"]
        P42831["PR #42831 (closed)"]
        P76081["PR #76081 (open)"]
    end
    P76081 -->|best fix| I42809
    class I42809 open
    class P42822 closed
    class P42823 closed
    class P42831 closed
    class P76081 open
    class P42831 best
    class P76081 best
    class P76081 target
    click I42809 "https://github.com/NousResearch/hermes-agent/issues/42809"
    click P42822 "https://github.com/NousResearch/hermes-agent/pull/42822"
    click P42823 "https://github.com/NousResearch/hermes-agent/pull/42823"
    click P42831 "https://github.com/NousResearch/hermes-agent/pull/42831"
    click P76081 "https://github.com/NousResearch/hermes-agent/pull/76081"

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Graph: solid arrow = fixes / best fix, dashed arrow = partial or unverified (see edge label); boxed group = PRs duplicating each other; amber border = best fix; indigo border = target; gray node = closed (state tag in the node label).

Cross-PR triage: Reviewed 4 pull requests and 1 issue in this complex. Each diff was read against this issue; Assessment working set: 10 kB of PR diffs, 7 kB of issue/PR text, 3 kB of discussion (8 comments), 8 verify verdicts. verdicts reflect diff content, not PR titles. Part of an automated triage batch.