Module 5: Cloud Security & Observability: Mistake Clinic

This clinic turns wrong moves into reusable judgment. Use it after each practice page and again before the quiz or checkpoint.

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Module-Specific Mistake Radar

Start with these traps. Replace or extend them with real mistakes from your own work.

Mistake to look for	Where it shows up	Symptom	Repair evidence
Finishing Threat Modeling Lab with only a final answer	Threat Modeling Lab	The work has no failed case, trace, test, proof gap, or design stress point.	Add the smallest broken example and show the repair that changes the result.
Finishing Secrets and Encryption Workshop with only a final answer	Secrets and Encryption Workshop	The work has no failed case, trace, test, proof gap, or design stress point.	Add the smallest broken example and show the repair that changes the result.
Finishing Observability Design Clinic with only a final answer	Observability Design Clinic	The work has no failed case, trace, test, proof gap, or design stress point.	Add the smallest broken example and show the repair that changes the result.
Finishing Security / Observability Code Katas with only a final answer	Security / Observability Code Katas	The work has no failed case, trace, test, proof gap, or design stress point.	Add the smallest broken example and show the repair that changes the result.
Treating Threat Modeling (STRIDE) for Cloud Services as vocabulary instead of a tool	Threat Modeling (STRIDE) for Cloud Services	The explanation names the concept but cannot decide between two cases.	Write one example, one non-example, and the rule that separates them.
Treating Identity-Centric Security: The New Perimeter as vocabulary instead of a tool	Identity-Centric Security: The New Perimeter	The explanation names the concept but cannot decide between two cases.	Write one example, one non-example, and the rule that separates them.

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Practice Mistake Checks

Pull any miss from these checks into your mistake log.

Threat Modeling Lab

Source: practice/01-threat-modeling-lab.md

For each statement, identify the error and the corrected version:

1. "We turned on encryption and enabled MFA, so the threat model is done."
2. "The database is in a private subnet, so application-level authorization is optional."
3. "This IAM role has *:* but it is 'only used for deploys', so it is safe."
4. "We have a threat model, but nobody has updated it in a year -- the system has not changed much, so we are fine."

Secrets and Encryption Workshop

Source: practice/02-secrets-and-encryption-workshop.md

For each statement, identify the error:

1. "We store the key in environment variables, which is secure because they're not on disk."
2. "We use KMS, so we're doing envelope encryption."
3. "HTTPS is enabled, so the data is encrypted end to end."
4. "We rotate the KEK, so the data is re-encrypted."
5. "We log the full request body for debugging -- it's internal, so PII is fine."

Observability Design Clinic

Source: practice/03-observability-design-clinic.md

For each statement, identify the error:

1. "Adding user_id as a label helps us see per-user behavior in metrics."
2. "We have logs, so we have observability."
3. "We sample 1% of traces, so errors are captured."
4. "The dashboard shows green, so the pipeline is running."
5. "This alert fires on CPU > 80%; it is a symptom alert."

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Repair Protocol

For each real mistake:

1. Reproduce the failure on the smallest example, trace, proof, query, command, or design sketch.
2. Name the hidden assumption.
3. Repair the artifact.
4. Save evidence that changed: failing then passing test, corrected proof step, revised diagram, safer command, benchmark, or review note.
5. Add one retrieval card beginning with Check... before... or Do not use... when....

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Mistake Log

Date	Mistake	Symptom	Root cause	Repair evidence	Retrieval card
Starter	Pick one radar row above	Explain how it would fail in this module	Name the assumption	Add a counterexample or corrected artifact	Write the card before closing the page

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Completion Standard

• At least five real mistakes are logged.
• At least two mistakes include a counterexample or failing test.
• At least one mistake connects to an older semester skill.
• At least one correction changes code, a proof, a diagram, a command transcript, a query, or a design decision.