feat(miner-config): parse a feasibility-gate policy block from .gittensory-miner.yml

[JSONbored]

.gittensory-miner.yml already has a real, tolerant parser and type — MinerGoalSpec (packages/gittensory-engine/src/miner-goal-spec.ts:14-52) currently covers six fields (minerEnabled, wantedPaths, blockedPaths, preferredLabels, blockedLabels, maxConcurrentClaims, issueDiscoveryPolicy); none of them govern the feasibility gate. parseMinerGoalSpec/parseMinerGoalSpecContent in the same file (lines 193-257) never throw — a malformed field degrades to DEFAULT_MINER_GOAL_SPEC (lines 72-80) plus a warning string. This is the canonical implementation: it's re-exported from the package entrypoint (packages/gittensory-engine/src/index.ts:190-198) and it's what the one real caller in the miner package actually uses (packages/gittensory-miner/lib/opportunity-ranker.js:57, parseMinerGoalSpecContent(content).spec).

Caution for whoever picks this up: there is a second, differently-behaved parseMinerGoalSpec function in a sibling file, packages/gittensory-engine/src/miner-goal-spec-parse.ts (110 lines, its own MinerGoalSpecParseResult return type, different limits — 200 list entries / 300 chars vs. the canonical file's 100 / 256). It is not exported from index.ts and has no caller anywhere in the repo outside its own test files (packages/gittensory-engine/test/miner-goal-spec-parse.test.ts, miner-goal-spec-discovery.test.ts). Extend miner-goal-spec.ts — that's the one every real consumer depends on; changing the other file would have zero effect on actual miner behavior.

The JSON Schema mirror, packages/gittensory-miner/schema/miner-goal-spec.schema.json, has "additionalProperties": true (line 7) and repeats the same six fields 1:1, so adding a feasibilityGate property is additive and non-breaking to the schema. packages/gittensory-miner/docs/miner-goal-spec.md documents the same six fields and will need the new one too.

This item is naturally paired with #4270 (wiring buildFeasibilityVerdict into an MCP tool + CLI command) — this issue is what would let a repo maintainer actually tune that gate's behavior per-repo — but the two can be built independently since this only touches the config-parsing surface, not the composer or its callers.

Deliverables

• Add a feasibilityGate field to MinerGoalSpec in packages/gittensory-engine/src/miner-goal-spec.ts — type + an entry in DEFAULT_MINER_GOAL_SPEC (lines 72-80) + a normalize* helper mirroring the existing ones (e.g. normalizeIssueDiscoveryPolicy, lines 138-150)
• Wire the new field through parseMinerGoalSpec (lines 193-231) and hasConfiguredGoalFields (lines 176-186, so a spec with only this field set is still correctly detected as present: true)
• Do NOT extend miner-goal-spec-parse.ts for this — it's a second, non-exported implementation with no real caller (see caution above)
• Update packages/gittensory-miner/schema/miner-goal-spec.schema.json with the new property
• Update packages/gittensory-miner/docs/miner-goal-spec.md
• Decide and document the policy block's shape — e.g. whether it can override/suppress specific buildFeasibilityVerdict avoid/raise reasons per-repo, or just tune thresholds — coordinating loosely with feat(miner-plan): wire the feasibility gate into a new MCP tool + miner CLI command #4270 since that issue is the gate's actual consumer
• Tests in packages/gittensory-engine/test/miner-goal-spec*.test.ts covering present/absent/malformed cases for the new field, mirroring the existing per-field test coverage

References

• packages/gittensory-engine/src/miner-goal-spec.ts:14-52 (MinerGoalSpec type)
• packages/gittensory-engine/src/miner-goal-spec.ts:72-80 (DEFAULT_MINER_GOAL_SPEC)
• packages/gittensory-engine/src/miner-goal-spec.ts:193-231 (parseMinerGoalSpec)
• packages/gittensory-engine/src/miner-goal-spec.ts:176-186 (hasConfiguredGoalFields)
• packages/gittensory-engine/src/index.ts:190-198 (public export — the canonical module)
• packages/gittensory-engine/src/miner-goal-spec-parse.ts (the non-exported, uncalled sibling — do not extend this one)
• packages/gittensory-miner/lib/opportunity-ranker.js:57 (the one real caller of parseMinerGoalSpecContent)
• packages/gittensory-miner/schema/miner-goal-spec.schema.json:7 ("additionalProperties": true)
• packages/gittensory-miner/docs/miner-goal-spec.md
• feat(miner-plan): wire the feasibility gate into a new MCP tool + miner CLI command #4270 (the feasibility-gate MCP tool + CLI wiring this config block would tune)
• Wave 2 tracker 🧩 Wave 2 — Analyze, Plan, Create & Deploy (HELD tracker) #2353, Phase 2

[linear-code]

JSO-3262